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Gastrointestinal Oral health

Halitosis

Last revised in September 2024

Halitosis (bad breath) is a general term that describes an unpleasant odour in the breath, regardless of the cause of the odour.

Halitosis: Summary

  • Halitosis ('bad breath' or 'oral malodour') is a general term used to describe an unpleasant or offensive odour in exhaled air, regardless of the underlying cause.
    • Physiological halitosis is usually transient and normal, for example, following a night's sleep ('morning breath') or fasting. Non-pathological halitosis may also be lifestyle-related, for example, caused by smoking or ingesting certain odiferous foods or drinks (such as onion, garlic, spices, and alcohol).
    • Pathological halitosis is usually intra-oral (for example caused by tongue coating, gingivitis, periodontitis, and poor denture hygiene) or more rarely extra-oral (such as nasal, paranasal, or laryngeal conditions; respiratory tract conditions; gastrointestinal conditions; metabolic disorders; or drugs).
    • Psychogenic or subjective (the person believes that they have halitosis when it is not objectively perceived or confirmed by others. In extreme forms this is termed halitophobia).
  • Halitosis is common, and may have a negative psychosocial impact including affecting the person's mood and quality of life.
  • Assessment of a person with self-reported halitosis should include:
    • Asking about the impact of symptoms including effect on behaviour and mood; the severity, timing during the day, and duration of symptoms; any lifestyle factors; dental history and oral hygiene routine; co-morbid conditions; and any contributory or causative drugs.
    • Asking about any concerns from the person's partner, friends, or family members.
    • Smelling the person's exhaled breath through the mouth and the nose, and comparing the two to identify a possible underlying cause.
    • Examining the person's teeth, tongue, and oral cavity to identify any oral cause for symptoms.
  • Management of a person with self-reported halitosis should include:
    • Providing reassurance and explanation about physiological halitosis.
    • Offering advice about sources of information and support.
    • Arranging a routine dental appointment for a full oral examination if there is a suspected oral cause for symptoms.
    • Encouraging lifestyle changes if appropriate.
    • Managing any underlying cause in primary care if appropriate.
    • Advising on the importance of general oral hygiene measures and attending regular dental appointments.
    • Re-assessing for objective evidence of halitosis if reported symptoms persist.
    • Arranging referral to an appropriate specialist if halitosis is secondary to an underlying cause that cannot be managed in primary care, or if self-reported halitosis persists despite self-management advice.

Have I got the right topic?

From age 16 years onwards.

This CKS topic covers the assessment and management of halitosis (bad breath) in primary care.

This CKS topic does not cover the assessment and management of oral problems in people receiving palliative care. This is covered in the CKS topic on Palliative care - oral.

There are separate CKS topics on Candida - oral, Dental abscess, Gingivitis and periodontitis, Head and neck cancers - recognition and referral, and Herpes simplex - oral.

The target audience for this CKS topic is healthcare professionals working within the NHS in the UK, and providing first contact or primary healthcare.

How up-to-date is this topic?

Changes

September 2024 — reviewed. A literature search was conducted in July 2024 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of this topic. No major changes to the recommendations have been made.

Previous changes

September 2019 — reviewed. A literature search was conducted in July 2019 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of the topic. The topic has undergone minor restructuring. The recommendations on the assessment and management of halitosis have been amended in line with current evidence. The node on Diagnosis has been deleted and incorporated into the node on Assessment in the Diagnosis section. The information in the Supporting Evidence section has been incorporated into the relevant Basis for recommendation sections.

August to November 2014 — reviewed. The evidence base has been reviewed in detail, and recommendations are clearly justified and transparently linked to the supporting evidence. No significant changes have been made to the recommendations.

September 2009 to January 2010 — this is a new CKS topic. The evidence-base has been reviewed in detail, and recommendations are clearly justified and transparently linked to the supporting evidence.

Update

New evidence

Evidence-based guidelines

  • No new evidence based guidelines since 1 July 2024.

HTAs (Health Technology Assessments)

No new HTAs since 1 July 2024.

Economic appraisals

No new economic appraisals relevant to England since 1 July 2024.

Systematic reviews and meta-analyses

No new systematic reviews published since 1 July 2024.

Primary evidence

No new primary evidence which reaches the CKS threshold for inclusion published since 1 July 2024.

New policies

No new national policies or guidelines since 1 July 2024.

New safety alerts

No new safety alerts since 1 July 2024.

Changes in product availability

No changes in product availability since 1 July 2024.

Goals and outcome measures

Goals

To support primary healthcare professionals to:

  • Confirm a diagnosis of halitosis in primary care.
  • Identify intra-oral or extra-oral causes of halitosis, and manage appropriately.
  • Arrange specialist referral where appropriate.
  • Advise on oral hygiene and lifestyle measures to manage halitosis.

Outcome measures

No outcome measures were found during the review of this topic.

Audit criteria

No audit criteria were found during the review of this topic.

QOF indicators

No QOF indicators were found during the review of this topic.

QIPP - Options for local implementation

No QIPP indicators were found during the review of this topic.

NICE quality standards

No NICE quality standards were found during the review of this topic.

Background information

What is it?

  • Halitosis ('bad breath' or 'oral malodour') describes an unpleasant or offensive odour in exhaled air. It can be classified as:
    • Physiological.
      • This is usually transient and normal, for example, following a night's sleep ('morning breath') or fasting.
      • Non-pathological halitosis may also be lifestyle-related, for example, caused by smoking or ingesting certain odiferous foods or drinks.
    • Pathological.
      • Intra-oral halitosis — the odour originates from a problem within the mouth (common).
      • Extra-oral halitosis — the odour originates from a non-oral disease (uncommon).
    • Psychogenic or subjective (the person believes that they have halitosis when it is not objectively perceived or confirmed by others).
      • Pseudo-halitosis — the person eventually accepts that they do not have halitosis with reassurance, explanation, and self-care advice.
      • Halitophobia — the person has a persistent fear of having halitosis despite reassurance, explanation, and treatment. They may become fixated with teeth and tongue cleaning, and may change their behaviour (such as covering their mouth when talking and avoiding people) to try and minimize perceived symptoms. In addition, they may misinterpret other people's behaviour (such as opening windows, sniffing, or touching the nose) as evidence of their halitosis.

[Aydin, 2014; Mokeem, 2014; Seemann, 2014; Singh, 2015; Kapoor, 2016; Silva, 2018; Wu, 2020; BMJ Best Practice, 2022; Khounganian, 2023]

What causes it?

There are multiple possible underlying causes of halitosis. Be aware that one or more causes may co-exist in any combination at any time in a person [Aydin, 2014].

  • Physiological or transient
    • This is common, usually transient, and typically resolves quickly after eating or drinking [Aydin, 2014; Mokeem, 2014; De Geest, 2016; Kapoor, 2016].
      • 'Morning breath' is thought to be due to reduced saliva flow combined with increased microbial activity and breakdown of food debris and other substrates in the mouth whilst asleep.
      • Halitosis may also follow fasting.
    • Smoking [Porter, 2006; Singh, 2015].
      • This can be due to the stale smell of tobacco. Smoking also predisposes to reduced salivation, tongue coating, and periodontal disease, which are additional causes of halitosis. See the CKS topic on Smoking cessation for more information.
    • Volatile foods and drinks [Porter, 2006; Aydin, 2014; Singh, 2015; Kapoor, 2016; Wu, 2020; BMJ Best Practice, 2022].
      • Examples include garlic, onion, spices, radishes, and alcohol. See the CKS topic on Alcohol - problem drinking for more information.
      • Often the halitosis is transient, but may persist or be recurrent if the causative food or drink is regularly consumed.
  • Intra-oral (accounts for 85–90% of cases of persistent, objective halitosis) [Porter, 2006; Aydin, 2014; Mokeem, 2014; Seemann, 2014; Singh, 2015; De Geest, 2016; Kapoor, 2016; Wu, 2020; BMJ Best Practice, 2022].
    • Often due to increased microbial activity of bacterial reservoirs within the mouth, which may be linked to poor oral hygiene.
      • Bacteria (especially Gram-negative anaerobes) in the oral cavity breakdown food debris, cells, saliva, and other substrates (such as blood or purulent postnasal secretions) lodged between the teeth, gums ('periodontal pockets'), in dental caries, and particularly on the posterior dorsal tongue. This results in the breakdown of sulphur-containing amino acids, which releases odiferous chemicals (such as volatile sulphur compounds, polyamines, indoles, and short chain fatty acids).
    • Conditions of the mouth and teeth can lead to localized accumulations of food debris and bacteria resulting in halitosis. These include:
      • Tongue coating (common) — particularly on the posterior dorsal tongue area.
      • Gingivitis and periodontitis (common) — gingivitis typically causes gum swelling, redness, and bleeding on toothbrushing or flossing; periodontitis typically causes gum recession, tooth loosening, and possible periodontal abscess. Severe halitosis may be associated with acute necrotizing ulcerative gingivitis ('Vincent's disease') — suggested by painful bleeding gums, gingival ulcers, fever, and general malaise. See the CKS topic on Gingivitis and periodontitis for more information.
      • Dry mouth (xerostomia) — the cleansing mechanism of the mouth is impaired by reduced salivary flow. This may be caused by smoking, alcohol, drugs, radiotherapy, chemotherapy, and Sjögren's syndrome.
      • Poor denture hygiene (for example, not taking dentures out at night and not cleaning regularly may allow accumulation of debris).
      • Other oral and dental diseases, including dry socket (alveolar osteitis), dental abscess, oral infections such as oral candidiasis or herpetic gingivostomatitis, oroantral fistula, and oral cancer. See the CKS topics on Dental abscess, Candida - oral, Herpes simplex - oral, and Head and neck cancers - recognition and referral for more information.
  • Extra-oral [Porter, 2006; Mokeem, 2014; Seemann, 2014; Singh, 2015; De Geest, 2016; Kapoor, 2016; Torsten, 2017; Wu, 2020; BMJ Best Practice, 2022].
    • Nasal, paranasal, and laryngeal conditions such as infection (oral candidiasis, sinusitis, tonsillitis, or nasopharyngeal abscess), tonsilloliths (mineralized debris in the tonsillar crypts), nasal foreign bodies, nasal obstruction/congestion leading to mouth breathing, postnasal drip, and malignancy. See the CKS topics on Candida - oral, Sinusitis, Sore throat - acute, and Head and neck cancers - recognition and referral for more information.
    • Respiratory conditions, such as upper respiratory tract infection (nasal secretions pass into the oropharynx in pharyngitis or laryngitis), lower respiratory infection or abscess, bronchiectasis, and lung cancer. See the CKS topics on Common cold, Cough, Sore throat - acute, Bronchiectasis, and Lung and pleural cancers - recognition and referral for more information.
    • Gastrointestinal tract conditions, such as gastro-oesophageal reflux disease, hiatus hernia, Helicobacter pylori infection, duodenal obstruction, oesophageal diverticulum, and gastrointestinal cancer. See the CKS topics on Dyspepsia - proven GORD and Gastrointestinal tract (upper) cancers - recognition and referral for more information.
    • Systemic diseases where blood-borne chemicals are excreted into the breath via the lungs, such as cirrhosis and hepatic failure; end-stage renal failure (uraemia); diabetic ketoacidosis; and other rare metabolic disorders such as trimethylaminuria ('fish odour syndrome') or hypermethioninaemia. See the CKS topics on Jaundice in adults, Chronic kidney disease, and Diabetes - type 1 for more information.
    • Drugs, including bisphosphonates, disulfiram, lithium, melatonin, metronidazole, nicotine lozenges, mycophenolate sodium, amyl nitrites, nitrates, phenothiazine, amphetamines, and some cytotoxic drugs.

How common is it?

There have been few epidemiologic studies investigating the prevalence of halitosis in the general population, and prevalence estimates vary depending on the definitions/terminology used, and population studied [Silva, 2018]. Many studies also rely on subjective self-estimation of malodour [BMJ Best Practice, 2022]. 

  • Halitosis is a common condition that can affect all age groups [Porter, 2006; Bollen, 2012; Scully, 2012; BMJ Best Practice, 2022].
    • A systematic review of 13 international population-based studies (n = 384,830) found an estimated worldwide prevalence of 31.8%. The authors noted, however, significant heterogeneity between the studies, including differing socioeconomic status of the study populations and year of study publication [Silva, 2018].
    • In the developed world, 8–50% of people perceive that they have persistent recurrent episodes of oral malodour [Porter, 2006].
      • There are no differences between males and females regarding the prevalence or severity of halitosis [Singh, 2015].
      • There may be a correlation between increasing age and the presence and severity of oral malodour [Kapoor, 2016].
      • Halitosis may be under-reported, as people are often not aware of their own oral malodour, or may be embarrassed to report it to healthcare professionals [Kapoor, 2016; Silva, 2018].
      • Severe halitosis is thought to affect less than 5% of the population [BMJ Best Practice, 2022].
  • Psychogenic or subjective halitosis may affect 0.5–1% of the general adult population, although the reported prevalence rates vary in the literature [Bollen, 2012].
    • In a German cross-sectional study of people reporting oral malodour to a multi-disciplinary clinic (n = 407), 28% did not show objective signs of halitosis, suggesting a diagnosis of pseudo-halitosis [Seemann, 2006].
      • Of these people, 36% had undergone gastroenterology investigations, and 14% had undergone ear, nose, and throat (ENT) surgery. The study authors concluded that people with this diagnosis are often misdiagnosed, over-investigated, and over-treated.
    • In a Belgian study of people who had predominantly self-referred to a multi-disciplinary clinic (n = 2000), 16% did not show objective signs of halitosis, suggesting a diagnosis of pseudo-halitosis or halitophobia [Quirynen et al, 2009].

What are the complications?

Potential complications of halitosis include:

Diagnosis of halitosis

How should I assess a person reporting halitosis?

If a person presents with self-reported halitosis, assess the person to confirm the diagnosis and identify any underlying cause.

  • Ask the person about:
    • Their own perception of the halitosis, including the impact on their quality of life (education, work, and social activities, relationships, anxiety, and mood), and changes in behaviour (such as covering the mouth when talking and avoiding social interactions). Note: be aware that the person's own assessment of their breath is not always reliable.
    • The severity, timing during the day, and duration of symptoms, for example, relation to certain foods or drinks, or following periods of hunger or starvation (may suggest physiological halitosis).
    • Additional symptoms such as dry mouth (which can lead to decreased taste sensation and difficulty in swallowing), mouth breathing, nasal discharge or obstruction, loss of sense of smell, cough, or weight loss.
    • Possible lifestyle factors, such as diet, smoking, and alcohol intake.
    • Dental history and oral hygiene routine, such as:
      • History of dental surgery including faulty restorations or ill-fitting prostheses.
      • Oral hygiene measures and frequency of toothbrushing, inter-dental cleaning, tongue cleaning, and use of mouthwashes/chewing gums/mints/sprays.
      • Use of a dental prosthesis (denture, orthodontic appliance, or bridge) and denture hygiene (if appropriate), including whether dentures are taken out at night and cleaned regularly.
      • Frequency of routine dental checks and any dental hygienist input.
    • Any medical history, including possible extra-oral causes of halitosis.
    • Any medications or recreational drugs that may cause or contribute to halitosis.
    • Any concerns from the person's partner, friends, or family members; their perception of the halitosis; and how they feel it is affecting the person (if possible and appropriate).
  • Confirm that objective halitosis is present by assessing the person's breath (so-called 'organoleptic testing').
    • Ideally, the person should not wear fragrances prior to the assessment. In addition, the person should not consume odiferous foods or drinks for 48 hours (and should ideally only drink water on the morning of the assessment); should not smoke for 12 hours; and should omit their usual oral hygiene routine for 24 hours prior to the assessment. This may be difficult to achieve in primary care.
    • Ask the person to breathe out of their mouth (pinching the nose), and then to breathe out of their nose (with the mouth closed), and smell the person's exhaled breath. Halitosis is likely to be:
      • Oral or pharyngeal in origin — if malodour is detected from the mouth but not from the nose.
      • Nasal or sinus in origin — if malodour is detected from the nose but not from the mouth.
      • Systemic in origin — if malodour from the nose and mouth are of equal intensity (rare).
    • Consider repeating the assessment on two or three occasions if no halitosis is detected on the initial examination.
  • Assess the person's oral health.
    • Examine the person's teeth, tongue, and oral cavity to assess for oral causes of halitosis, such as misaligned teeth, dental caries, periodontal disease, tongue coating, and plaque.
      • Be aware that tongue coating may be a cause of halitosis even in people with otherwise good dental hygiene and oral health.
      • Consider gently scraping the posterior tongue area (for example, with a clean plastic spoon), as the odour from the scraping is generally similar to overall mouth odour.

Basis for recommendation

The recommendations on assessment of a person with halitosis are largely based on expert opinion in an international consensus document Halitosis management by the general dental practitioner - results of an international consensus workshop [Seemann, 2014] the BMJ Best Practice guideline Halitosis [BMJ Best Practice, 2022], and expert opinion in review articles on halitosis [Eli, 2001; Porter, 2006; Vandekerckhove, 2009; Bollen, 2012; Scully, 2012; Zalewska, 2012; Aydin, 2014; Mokeem, 2014; Singh, 2015; De Geest, 2016; Kapoor, 2016; Wu, 2020].

History-taking

  • The recommendations on relevant clinical features is based on expert opinion in the international consensus document [Seemann, 2014], the BMJ Best Practice guideline [BMJ Best Practice, 2022], and in review articles [Eli, 2001; Porter, 2006; Aydin, 2014; Singh, 2015; Kapoor, 2016].
    • The information that it may be difficult for a person with halitosis to accurately assess the severity of their own oral odour is based on expert opinion in review articles [Eli, 2001; Porter, 2006].
    • The information on additional symptoms to ask about to help indicate an underlying oral or extra-oral cause is based on expert opinion in a review article [Kapoor, 2016] and the BMJ Best Practice guideline [BMJ Best Practice, 2022].
    • The recommendation to ask about dental history and dental prostheses is based on expert opinion in a review article [Kapoor, 2016].
    • The recommendation to ask for a collateral history from partner, friends, or family is based on expert opinion in a review article, which notes that there is interpersonal variation in the emotional reactions to detected odour [Aydin, 2014].

Assessing for objective halitosis ('organoleptic testing')

Oral examination

  • The information on the oral examination to check for conditions that may predispose to bacterial colonization and production of odiferous compounds, and how to assess tongue coating are based on expert opinion  [Singh, 2015; Kapoor, 2016; BMJ Best Practice, 2022].

Management

Scenario: Management of halitosis

From age 16 years onwards.

How should I manage a person reporting halitosis?

If a person self-reports halitosis and has been assessed:

  • Reassure the person that transient halitosis (such as 'morning breath' on waking) is normal and common, and usually resolves with eating or drinking, toothbrushing, and/or rinsing the mouth with water.
  • Offer advice about sources of information and support, such as the NHS information leaflet Bad breath.
  • If there is any uncertainty about the possibility of oral disease (such as gingivitis or periodontitis), advise or arrange a routine dental appointment for a full oral examination, especially if the person does not attend dental appointments regularly.
  • Encourage lifestyle changes if appropriate, such as:
    • Avoiding or limiting causative foods or drinks.
    • Drinking sufficient fluids; eating breakfast; chewing; eating acidic foods; and sucking sugar-free sweets or chewing sugar-free gum if the person reports a dry mouth.
    • Stopping smoking. See the CKS topic on Smoking cessation for more information.
    • Limiting excess alcohol intake. See the CKS topic on Alcohol - problem drinking for more information.
  • If an underlying cause of halitosis has been identified, arrange appropriate management in primary care or arrange specialist referral if needed.
    • Consider the use of an artificial salivary substitute if lifestyle measures are insufficient to manage dry mouth symptoms. See the CKS topic on Palliative care - oral for more information.
  • If no underlying cause of halitosis has been identified:
    • Advise on the importance of general oral hygiene measures, including cleaning the teeth, interdental spaces, and tongue. The NHS leaflet Take care of your teeth and gums may be helpful.
    • Advise to limit the frequency and amount of sugary food and drinks (ideally maximum of four times a day, mainly at mealtimes).
    • Advise on the importance of attending regular dental appointments to ensure maintenance of good oral hygiene.
    • Note: it may be difficult for people to accurately assess the severity and improvement of their own oral odour following treatment.
  • For people without detectable halitosis following repeated assessment of the person's exhaled breath on two or three occasions:
    • Offer reassurance, explanation, and advise on self-management measures. These may be sufficient to resolve symptoms if the person has a diagnosis of pseudo-halitosis.
    • Consider a diagnosis of halitophobia if a person continues to report halitosis following this, and offer specialist referral.

Oral hygiene measures

Advise the person that the management of persisting halitosis is based on good oral hygiene, in particular, clearing or reducing any accumulation of food debris and bacteria on the tongue and teeth.

  • Give advice on general oral hygiene measures.
    • Clean daily between the teeth to below the gumline before brushing.
    • For small interdental spaces, use dental floss or tape.
    • For larger interdental spaces, use interdental or single-tufted brushes.
    • For around orthodontic appliances and bridges, use the kit suggested by the person's dentist.
  • Brush the teeth and gumline with a fluoridated toothpaste last thing at night, and at least on one other occasion in the day.
    • Use a manual or powered toothbrush with a small head and medium texture.
    • Thorough cleaning takes at least 2 minutes.
    • Spit out after brushing and do not rinse, to maintain fluoride concentration.
  • Perform daily tongue cleaning, ideally before bedtime.
    • In particular, clean the posterior part of the upper tongue, where bacteria flourish.
    • Advise to use a proprietary tongue cleaner/scraper rather than a toothbrush.
    • Use a gentle scraping action, and avoid excessive scraping as this can cause damage and bleeding to the tongue.
    • Cleaning should be repeated until no more coating material can be removed.
    • Care should be taken to avoid triggering the gag reflex.
  • Advise denture wearers that these should be left out at night and cleaned.
    • The person should consult their dentist if there are any issues with the dentures or other dental prostheses, including how they fit.
  • Give advice on antibacterial mouthwashes/toothpastes and non-antibacterial preparations, if halitosis persists despite these measures.
    • An antibacterial mouthwash such as chlorhexidine and/or toothpaste such as triclosan may help symptoms, and can be bought over-the-counter.
      • Other antibacterial agents include cetylpyridinium chloride, hexetidine, hydrogen peroxide, and zinc; the choice of preparation will depend on individual preference and product tolerability.
      • Advise that chlorhexidine products may cause reversible discolouration of the tongue, teeth, or dentures (which can be minimized by brushing teeth before using a chlorhexidine-based product, and cleaning dentures with a conventional denture cleanser). They may also cause transient taste disturbance and a burning sensation of the tongue, which usually diminish with continued use.
    • Various non-antibacterial products (such as mints, flavoured/perfumed mouth sprays/rinses, and chewing gums) may provide transient masking of halitosis.

Basis for recommendation

The recommendations on management of halitosis in primary care are largely based on an international consensus document Halitosis management by the general dental practitioner - results of an international consensus workshop [Seemann, 2014], the UK Health Security Agency (UKHSA) publication Delivering better oral health: an evidence-based toolkit for prevention [UKHSA, 2021], the BMJ Best Practice guideline Halitosis [BMJ Best Practice, 2022], systematic reviews on the effect of professional tooth cleaning on oral malodour [Deutscher, 2017],  the impact of toothbrushing and tongue cleaning [Kuo, 2013], and the impact of mouthwashes on oral malodour [Blom, 2012], and expert opinion in review articles on halitosis [Porter, 2006; Bollen, 2012; Scully, 2012; Zalewska, 2012; Aydin, 2014; Mokeem, 2014; Singh, 2015; De Geest, 2016; Kapoor, 2016; Wu, 2020].

Reassurance, information, and advice
Routine dental appointment
  • A systematic review of eight observational studies or study arms on the impact of professional tooth cleaning found this had a positive effect on volatile sulphur compounds or organoleptic scores after the intervention. Overall, professional tooth cleaning in combination with standard oral hygiene measures had the most impact, independent of tongue cleaning and the use of mouthwashes. The authors noted, however, significant heterogeneity between the studies, and a meta-analysis was not possible [Deutscher, 2017].
  • This approach is supported by expert opinion in a review article [De Geest, 2016] and the expert opinion of previous external reviewers of this CKS topic, which noted that some oral conditions (such as periodontitis) may be difficult to diagnose by a non-dental professional by visual examination alone.
Lifestyle changes
  • The recommendations on general lifestyle strategies to reduce halitosis are based on expert opinion in a review article [Kapoor, 2016].
  • The advice on strategies to stimulate saliva production for people with a dry mouth is based on expert opinion in review articles [Singh, 2015; De Geest, 2016].
Oral hygiene measures
  • The recommendations on the benefits of effective tooth cleaning (brushing and interdental flossing) and tongue cleaning are largely based on the international consensus document [Seemann, 2014], the UK Health Security Agency (UKHSA) publication  [UKHSA, 2021], the BMJ Best Practice guideline [BMJ Best Practice, 2022], and expert opinion in review articles [Porter, 2006; Bollen, 2012; Scully, 2012; Zalewska, 2012; Singh, 2015; De Geest, 2016; Kapoor, 2016].
    • Regular oral hygiene measures are important for the prevention of caries, plaque, and gingivitis, and for the daily clearance of food debris in the mouth, which may contribute to the development of halitosis.
    • The tongue is the biggest reservoir of bacteria involved in the production of malodourous compounds that cause halitosis, and tongue cleaning is likely to reduce tongue coating and symptoms [Seemann, 2014; Kapoor, 2016]. Regular tongue cleaning may reduce levels of volatile sulphur compounds by more than 70% [De Geest, 2016].
    • Tongue cleaning is unlikely to cause harm and may provide short-term benefit [Porter, 2006].
    • A systematic review and meta-analysis of five randomized controlled trials (RCTs, n = 251 adults) of tongue cleaning plus toothbrushing compared with toothbrushing alone found [Kuo, 2013]:
      • Studies using measures of volatile sulphur compounds as the outcome indicated the pooled effect size of tongue cleaning plus toothbrushing compared to toothbrushing alone was statistically significant at reducing levels of volatile sulphur compounds. There was insufficient evidence, however, to recommend the optimal frequency, duration, or delivery method of tongue cleaning.
  • The recommendations on the possible benefits of antibacterial mouthwashes/toothpastes and non-antibacterial preparations, as well as the information on their components and active ingredients, are largely based on information from the British National Formulary [BNF, 2024], the UKHSA publication [UKHSA, 2021], the international consensus document [Seemann, 2014], and review articles [Porter, 2006; Bollen, 2012; Scully, 2012; Zalewska, 2012; Mokeem, 2014; Singh, 2015; De Geest, 2016; Kapoor, 2016; Wu, 2020].
  • Antibacterial mouthwashes act by reducing bacterial load or associated odiferous compounds in the oral cavity [Porter, 2006].
  • A systematic review of eight short-term RCTs (less than three weeks' duration; n = 179) and three longer-term RCTs (more than three weeks' duration; n = 306) on the effectiveness of mouthwashes on oral malodour found [Blom, 2012]:
    • Nearly all mouthwashes with active ingredients had some beneficial effects in reducing oral malodour in both short- and longer-term studies.
    • The quality of the evidence was very low to moderate, and was primarily based on short-term studies.
    • Chlorhexidine mouthwashes, and those that contained a combination of chlorhexidine, cetylpyridinum chloride, and zinc, provided the best evidence profile on reducing oral malodour.
    • The information that various non-antibacterial products (such as mints, flavoured/perfumed mouth sprays/rinses, and chewing gums) may provide transient masking of halitosis is based on expert opinion in review articles [De Geest, 2016; Kapoor, 2016].
  • The recommendation to limit the frequency and amount of sugary food and drinks consumed is based on the UKHSA publication [UKHSA, 2021], and is supported by the expert opinion of previous external reviewers of this CKS topic.
  • The recommendation to attend regular dental reviews to ensure effective oral hygiene is based on expert opinion in review articles, as professional management may include treatment of periodontal disease that may be an underlying cause of halitosis [Porter, 2006; Singh, 2015].
  • The information that it may be difficult for people to accurately assess the severity or improvement of their own oral odour is based on expert opinion in a review article [Porter, 2006].
Pseudo-halitosis or halitophobia
  • The recommendations on managing pseudo-halitosis and halitophobia are based on the international consensus document [Seemann, 2014] and expert opinion in review articles [Porter, 2006; Mokeem, 2014; Singh, 2015; Kapoor, 2016]. They are also pragmatic, based on what CKS considers to be good clinical practice.

When should I refer?

Arrange specialist referral if halitosis is suspected to be secondary to an underlying cause that requires urgent assessment, cannot be managed in primary care, or if self-reported halitosis persists despite initial oral hygiene measures and lifestyle changes.

  • Arrange an urgent referral to an ear, nose, and throat (ENT) or oral medicine specialist, depending on clinical judgement and local referral pathways, if there is:
  • Arrange a routine referral to an ear, nose, and throat (ENT) specialist, if there is:
    • A history of recurrent tonsillitis. See the CKS topic on Sore throat - acute for more information.
    • Suspected sinonasal disease, such as septal deviation or recurrent sinusitis. See the CKS topic on Sinusitis for more information.
  • Advise a dental appointment for a full oral examination, if there is:
  • Arrange a referral to a respiratory or gastroenterology specialist, depending on the clinical presentation, if there is a suspected underlying cause for symptoms that cannot be managed in primary care.
  • Arrange a referral to an endocrinology specialist, if there is a suspected underlying metabolic cause for symptoms that cannot be managed in primary care.
  • Arrange a referral for counselling, psychological therapy, or psychiatric assessment, the urgency depending on clinical judgement, if there is:
    • A diagnosis of suspected halitophobia, where there are persistent symptoms without objective evidence of halitosis.
    • Significant distress associated with perceived halitosis that persists despite reassurance and explanation in primary care.

Basis for recommendation

The recommendations on referral are largely based on the National Institute for Health and Care Excellence (NICE) clinical guideline Suspected cancer: recognition and referral [NICE, 2023], the Scottish Dental Clinical Effectiveness Programme guidelines Prevention and treatment of periodontal diseases in primary care [SDcep, 2024], an international consensus document Halitosis management by the general dental practitioner - results of an international consensus workshop [Seemann, 2014], and expert opinion in review articles on halitosis [Porter, 2006; Scully, 2012; Mokeem, 2014; Singh, 2015; De Geest, 2016; Kapoor, 2016].

Referral
  • The recommendations on urgent referral if there is a lip or oral cavity lump; red or red and white patches in the oral cavity; or persistent ulceration in the oral cavity are based on advice within the NICE guideline [NICE, 2023].
  • The recommendation on referral for unexplained or atypical gingival enlargement is based on the Scottish Dental Clinical Effectiveness Programme guideline, which states that this can be a sign of undiagnosed leukaemia and urgent referral to a physician should be considered if the clinical picture is inconsistent with the person's level of oral hygiene [SDcep, 2024].
  • The recommendations on when to arrange a routine ENT referral are extrapolated from expert opinion in review articles [Mokeem, 2014; De Geest, 2016].
  • The recommendation to arrange specialist referral if there is a suspected extra-oral cause depending on the clinical presentation is based on expert opinion in the international consensus document [Seemann, 2014] and in review articles [Mokeem, 2014; Singh, 2015; Kapoor, 2016]
  • The recommendations on when to arrange psychological support or psychiatric assessment are based on expert opinion in the international consensus document [Seemann, 2014] and in review articles [Porter, 2006; Mokeem, 2014; Singh, 2015; Kapoor, 2016], and are also pragmatic, based on what CKS considers to be good clinical practice.
Dental appointment
  • Dental professionals are able to confirm or rule out oral causes of halitosis and may recommend professional tooth cleaning to improve symptoms [Kapoor, 2016]. In addition, they may arrange a dental X-ray to assess for evidence of dental caries, alveolar bone defects, and defective restorations [Singh, 2015].
    • This approach is supported by expert opinion in a review article [De Geest, 2016] and the expert opinion of previous external reviewers of this CKS topic, who noted that some oral conditions (such as periodontitis) may be difficult to diagnose by a non-dental professional by visual examination alone.
  • In the absence of oral or dental infection, a dental professional may advise empirical antibiotic treatment with metronidazole for management of refractory halitosis, to eliminate occult anaerobic infections [Scully, 2012; Mokeem, 2014].

Supporting evidence

This CKS topic is largely based on the National Institute for Health and Care Excellence (NICE) clinical guideline Suspected cancer: recognition and referral [NICE, 2023], an international consensus document Halitosis management by the general dental practitioner - results of an international consensus workshop [Seemann, 2014], the UK Health Security Agency (UKHSA) publication Delivering better oral health: an evidence-based toolkit for prevention [UKHSA, 2021], and the BMJ Best Practice guideline Halitosis [BMJ Best Practice, 2022], as well as expert opinion in review articles. The rationale for the individual recommendations is discussed in the relevant basis for recommendation sections.

How this topic was developed

This section briefly describes the processes used in developing and updating this topic. Further details on the full process can be found in the About Us section and on the Clarity Informatics website.

Search strategy

A literature search was conducted for guidelines and systematic reviews on primary care management of halitosis.

Search dates

July 2019 - July 2024

Key search terms

The terms listed below are the core search terms that were used for EBSCOhost MEDLINE (searched 26th July 2019). These were combined with filters to identify guidelines, systematic reviews and primary care relevant literature in EBSCOhost MEDLINE. The strategy was adapted for The Cochrane Library databases. 

S6    S1 OR S2 OR S3 OR S4 OR S5 
S5    AB ( (oral or mouth) N2 (odor* or odour*) ) OR TI ( (oral or mouth) N2 (odor* or odour*) ) 
S4    AB ( (oral or mouth) N2 (malodor* or malodour*) ) OR TI ( (oral or mouth) N2 (malodor* or malodour*) ) 
S3    AB bad breath OR TI bad breath 
S2    AB ( halitosis or halitoses ) OR TI ( halitosis or halitoses ) 
S1    (MH "Halitosis") 

Sources of guidelines

Sources of systematic reviews and meta-analyses

  • The Cochrane Library:
    • Systematic reviews
    • Protocols
    • Database of Abstracts of Reviews of Effects
  • Medline (with systematic review filter)
  • EMBASE (with systematic review filter)

Sources of health technology assessments and economic appraisals

Sources of randomized controlled trials

  • The Cochrane Library:
    • Central Register of Controlled Trials
  • Medline (with randomized controlled trial filter)
  • EMBASE (with randomized controlled trial filter)

Sources of evidence based reviews and evidence summaries

Sources of national policy

Patient experiences

Sources of medicines information

The following sources are used by CKS pharmacists and are not necessarily searched by CKS information specialists for all topics. Some of these resources are not freely available and require subscriptions to access content.

Stakeholder engagement

Our policy

The external review process is an essential part of CKS topic development. Consultation with a wide range of stakeholders provides quality assurance of the topic in terms of:

  • Clinical accuracy.
  • Consistency with other providers of clinical knowledge for primary care.
  • Accuracy of implementation of national guidance (in particular NICE guidelines).
  • Usability.

Principles of the consultation process

  • The process is inclusive and any individual may participate.
  • To participate, an individual must declare whether they have any competing interests or not. If they do not declare whether or not they have competing interests, their comments will not be considered.
  • Comments received after the deadline will be considered, but they may not be acted upon before the clinical topic is issued onto the website.
  • Comments are accepted in any format that is convenient to the reviewer, although an electronic format is encouraged.
  • External reviewers are not paid for commenting on the draft topics.
  • Discussion with an individual or an organization about the CKS response to their comments is only undertaken in exceptional circumstances (at the discretion of the Clinical Editor or Editorial Steering Group).
  • All reviewers are thanked and offered a letter acknowledging their contribution for the purposes of appraisal/revalidation.
  • All reviewers are invited to be acknowledged on the website. All reviewers are given the opportunity to feedback about the external review process, enabling improvements to be made where appropriate.

Stakeholders

  • Key stakeholders identified by the CKS team are invited to comment on draft CKS topics. Individuals and organizations can also register an interest to feedback on a specific topic, or topics in a particular clinical area, through the Getting involved section of the Clarity Informatics website.
  • Stakeholders identified from the following groups are invited to review draft topics:
    • Experts in the topic area.
    • Professional organizations and societies (for example, Royal Colleges).
    • Patient organizations, Clarity has established close links with groups such as Age UK and the Alzheimer’s Society specifically for their input into new topic development, review of current topic content and advice on relevant areas of expert knowledge.
    • Guideline development groups where the topic is an implementation of a guideline.
    • The British National Formulary team.
    • The editorial team that develop MeReC Publications.
  • Reviewers are provided with clear instructions about what to review, what comments are particularly helpful, how to submit comments, and declaring interests.

Patient engagement

Clarity Informatics has enlisted the support and involvement of patients and lay persons at all stages in the process of creating the content which include:

  • Topic selection
  • Scoping of topic
  • Selection of clinical scenarios
  • First draft internal review
  • Second draft internal review
  • External review
  • Final draft and pre-publication

Our lay and patient involvement includes membership on the editorial steering group, contacting expert patient groups, organizations and individuals.

Evidence exclusion criteria

Our policy

Scoping a literature search, and reviewing the evidence for CKS is a methodical and systematic process that is carried out by the lead clinical author for each topic. Relevant evidence is gathered in order that the clinical author can make fully informed decisions and recommendations. It is important to note that some evidence may be excluded for a variety of reasons. These reasons may be applied across all CKS topics or may be specific to a given topic.

Studies identified during literature searches are reviewed to identify the most appropriate information to author a CKS topic, ensuring any recommendations are based on the best evidence. We use the principles of the GRADE and PICOT approaches to assess the quality of published research. We use the principles of AGREE II to assess the quality of published guidelines.

Standard exclusions for scoping literature:

  • Animal studies
  • Original research is not written in English

Possible exclusions for reviewed literature:

  • Sample size too small or study underpowered
  • Bias evident or promotional literature
  • Population not relevant
  • Intervention/treatment not relevant
  • Outcomes not relevant
  • Outcomes have no clear evidence of clinical effectiveness
  • Setting not relevant
  • Not relevant to UK
  • Incorrect study type
  • Review article
  • Duplicate reference

Organizational, behavioural and financial barriers

Our policy

The CKS literature searches take into consideration the following concepts, which are discussed at the initial scoping of the topic.

  • Feasibility
    • Studies are selected depending on whether the intervention under investigation is available in the NHS and can be practically and safely undertaken in primary care.
  • Organizational and Financial Impact Analysis
  • Studies are selected and evaluated on whether the intervention under investigations may have an impact on local clinical service provision or national impact on cost for the NHS. The principles of clinical budget impact analysis are adhered to, evaluated and recorded by the author. The following factors are considered when making this assessment and analysis.
    • Eligible population
    • Current interventions
    • Likely uptake of new intervention or recommendation
    • Cost of the current or new intervention mix
    • Impact on other costs
    • Condition-related costs
    • In-direct costs and service impacts
    • Time dependencies
  • Cost-effectiveness or cost-benefit analysis studies are identified where available. 

We also evaluate and include evidence from NICE accredited sources which provide economic evaluations of recommendations, such as NICE guidelines. When a recommended action may not be possible because of resource constraints, this is explicitly indicated to healthcare professionals by the wording of the CKS recommendation.

Declarations of interest

Our policy

Clarity Informatics requests that all those involved in the writing and reviewing of topics, and those involved in the external review process to declare any competing interests. Signed copies are securely held by Clarity Informatics and are available on request with the permission of the individual. A copy of the declaration of interest form which participants are asked to complete annually is also available on request. A brief outline of the declarations of interest policy is described here and full details of the policy is available on the Clarity Informatics website. Declarations of interests of the authors are not routinely published, however competing interests of all those involved in the topic update or development are listed below. Competing interests include:

  • Personal financial interests
  • Personal family interest
  • Personal non-financial interest
  • Non-personal financial gain or benefit

Although particular attention is given to interests that could result in financial gains or losses for the individual, competing interests may also arise from academic competition or for political, personal, religious, and reputational reasons. An individual is not obliged to seek out knowledge of work done for, or on behalf of, the healthcare industry within the departments for which they are responsible if they would not normally expect to be informed.

Who should declare competing interests?

Any individual (or organization) involved in developing, reviewing, or commenting on clinical content, particularly the recommendations should declare competing interests. This includes the authoring team members, expert advisers, external reviewers of draft topics, individuals providing feedback on published topics, and Editorial Steering Group members. Declarations of interest are completed annually for authoring team and editorial steering group members, and are completed at the start of the topic update and development process for external stakeholders.

Competing interests declared for this topic:

None.

References

  • Aydin, M. and Harvey-Woodworth, C.N. (2014) Halitosis: a new definition and classification. British Dental Journal 217(1), 1-21. [Abstract]
  • Blom, T., Slot, D.E., Quirynen, M. and Van der Weijden, G.A. (2012) The effect of mouthrinses on oral malodor: a systematic review. International Journal of Dental Hygiene 10(3), 209-22. [Abstract]
  • BMJ Best Practice (2022) Halitosis. BMJ Publishing Group.
  • BNF (2024) British National Formulary. National Institute for Health and Care Excellence. https://bnf.nice.org.uk
  • Bollen, C.M. and Beikler, T. (2012) Halitosis: the multidisciplinary approach. International Journal of Oral Science 4(2), 55-63. [Abstract]
  • De Geest, S., Laleman, I., Teughels, W., et al. (2016) Periodontal diseases as a source of halitosis: a review of the evidence and treatment approaches for dentists and dental hygienists. Periodontology 2000 71(1), 213-227. [Abstract]
  • de Jongh, A., van Wijk, A.J., Horstman, M. and de Baat, C. (2014) Attitudes towards individuals with halitosis: an online cross sectional survey of the Dutch general population. British Dental Journal 216(4), 1038. [Abstract]
  • Deutscher, H.C.D., Derman, S.H.M., Barbe, A.G. et al. (2017) The effect of professional tooth cleaning or non-surgical periodontal therapy on oral halitosis in patients with periodontal diseases. A systematic review. International Journal of Dental Hygiene 16(1), 36-47. [Abstract]
  • Eli, I., Baht, R., Koriat, H. and Rosenberg, M. (2001) Self-perception of breath odor. Journal of the American Dental Association 132(5), 621-626. [Abstract]
  • Kapoor, U., Sharma, G., Juneja, M. and Nagpal, A. (2016) Halitosis: current concepts on etiology, diagnosis and management. European Journal of Dentistry 10(2), 292-300. [Abstract]
  • Khounganian, R.M., Alasmari, O.N., Aldosari, M.M. and Alghanemi, N.M. (2023) Causes and Management of Halitosis: A Narrative Review. Cureus 15(8), e43742. [Abstract]
  • Kuo, Y.W., Yen, M., Fetzer, S. and Lee, J.D. (2013) Toothbrushing versus toothbrushing plus tongue cleaning in reducing halitosis and tongue coating: a systematic review and meta-analysis. Nursing Research 62(6), 422-9.
  • Mokeem, S.A. (2014) Halitosis: a review of the etiologic factors and association with systemic conditions and its management. Journal of Contemporary Dental Practice 15(6), 806-811. [Abstract]
  • NICE (2023) Suspected cancer: recognition and referral. National Institute for Health and Care Excellence. http://www.nice.org.uk [Free Full-text]
  • Porter, S.R. and Scully, C. (2006) Oral malodour (halitosis). British Medical Journal 333(7569), 632-635. [Abstract]
  • Quirynen, M., Dadamio, J., Van den Velde, S., et al. (2009) Characteristics of 2000 patients who visited a halitosis clinic. Journal of Clinical Periodontology 36(11), 970-975. [Abstract]
  • Scully, C. and Greenman, J. (2012) Halitology (breath odour: aetiopathogenesis and management). Oral diseases 18, 333-345. [Abstract]
  • SDcep (2024) Prevention and Treatment of Periodontal Diseases in Primary Care. Scottish Dental Clinical Effectiveness Programme. https://www.sdcep.org.uk [Free Full-text]
  • Seemann, R., Bizhang, M., Djamchidi, C., et al. (2006) The proportion of pseudo-halitosis patients in a multidisciplinary breath malodour consultation. International Dental Journal 56(2), 77-81. [Abstract]
  • Seemann, R., Conceicao, M.D., Filippi, A., et al. (2014) Halitosis management by the general dental practitioner--results of an international consensus workshop. Journal of Breath Research 8(1), 017101. [Abstract]
  • Silva, M.F., Leite, F.R.M., Ferreira, L.B., et al. (2018) Estimated prevalence of halitosis: a systematic review and meta-regression analysis. Clinical Oral Investigations 22(1), 47-55. [Abstract]
  • Singh, V.P., Malhotra, N., Apratim, A. and Verma, M. (2015) Assessment and management of halitosis. Dental Update 42(4), 346-353. [Abstract]
  • Torsten, M., Gomez-Moreno, G. and Aguilar-Salvatierra, A. (2017) Drug-related oral malodour (halitosis): a literature review. European Reviews of Medical and Pharmacological Science 21(21), 4930-4934. [Abstract]
  • UKHSA (2021) Delivering better oral health: an evidence-based toolkit for prevention. UK Health Security Agency. https://www.gov.uk [Free Full-text]
  • Vandekerckhove, B., Van den Velde, S., De Smit, M., et al. (2009) Clinical reliability of non-organoleptic oral malodour measurements. Journal of Clinical Periodontology 36(11), 964-969. [Abstract]
  • Wu, J., Cannon, R.D., Ji, P., et al. (2020) Halitosis: prevalence, risk factors, sources, measurement and treatment - a review of the literature. Australian Dental Journal 65(1), 4-11. [Abstract]
  • Zalewska, A., Zatonski, M., Jablonka-Strom, A., et al. (2012) Halitosis - a common medical and social problem. A review on pathology, diagnosis and treatment. Acta gastro-enterologica Belgica 75(3), 300-309. [Abstract]
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