Previous changes

May 2024 — minor update. Information added stating that concomitant treatment with clarithromycin and ivabradine is now contra-indicated and caution is now advised when co-administering clarithromycin with edoxaban, as per the manufacturer's updated SPC.

December 2023 — minor update. Update to drug interactions section for erythromycin to include information on interactions with Lomitapide and Corticosteroids, as per the manufacturer's Summary of Product Characteristics (SPC).

November 2023 — minor update. Interactions section for flucloxacillin updated in line with updated manufacturer's summary of product characteristics.

July 2022 — minor update. Information that Naspetin® was recently reformulated and no longer contains arachis oil (peanut oil) has been added to this topic in line with the updated Summary of Product Characteristics. 

February 2022 — minor update. Links to key therapeutic topic guidance removed as service has been retired.

March to May 2021 — reviewed. A literature search was conducted in March 2021 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.

January 2021 — minor update. Contraindications and drug interactions for erythromycin have been updated in line with an MHRA drug safety update. 

November 2016 to January 2017 — reviewed. A literature search was conducted in November 2016 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of this topic. Changes include: following treatment for staphylococcal carriage, three clear swabs over a 3-week period are required to confirm eradication. This recommendation was removed as repeat screening is not routinely recommended; for recurrent boils, the recommendation to treat with the appropriate antibiotic (according to swab results) for 10-14 days was changed to 7 days, in line with what CKS considers to be good clinical practice; the choice of antiseptics for use in staphylococcal decolonization was amended in line with PHE guidance.

July 2015 — minor update. The prescribing information sections on erythromycin and clarithromycin have been clarified.

February 2013 — minor update. The 2013 QIPP options for local implementation have been added to this topic.

October 2012 — minor update. The 2012 QIPP options for local implementation have been added to this topic.

July 2011 — minor update. More exact paracetamol dosing for children has been introduced by the Medicines and Healthcare products Regulatory Agency. Prescriptions have been updated to reflect the revised dosing. Issued in July 2011.

May 2011 — minor update. The 2010/2011 QIPP options for local implementation have been added to this topic. Issued in June 2011.

October 2010 to March 2011 —  topic revised. The evidence-base has been reviewed in detail, and recommendations are more clearly justified and transparently linked to the supporting evidence.

July 2007 — Oilatum Plus discontinued. Minor change to the text made and prescriptions removed. Issued in August 2007.

December 2006 to March 2007— converted topic structure. The evidence-base has been reviewed in detail, and recommendations are more clearly justified and transparently linked to the supporting evidence.

October 2006 — minor update. Analgesia prescriptions updated because new doses of ibuprofen for children are recommended by the British National Formulary. Issued in October 2006.

October 2005 — minor technical update. Issued in November 2005.

September 2003 — written. Validated in December 2003 and issued in February 2004.

New evidence

Evidence-based guidelines

No new evidence-based guidelines since 1 May 2021.

HTAs (Health Technology Assessments)

No new HTAs since 1 May 2021.

Economic appraisals

No new economic appraisals relevant to England since 1 May 2021.

Systematic reviews and meta-analyses

No new systematic reviews or meta-analysis which reach the CKS threshold for inclusion since 1 May 2021.

Primary evidence

No new primary evidence which reaches the CKS threshold for inclusion published since 1 May 2021.

New policies

No new national policies or guidelines since 1 May 2021.

New safety alerts

No new safety alerts since 1 May 2021.

Changes in product availability

• Secukinumab for treating moderate to severe hidradenitis suppurativa. NICE recommends secukinumab as an option for treating active moderate to severe hidradenitis suppurativa (acne inversa) in adults who have not responded well enough to conventional systemic treatment, only if adalimumab is not suitable, did not work or has stopped working. See more here.

What is staphylococcal carriage?

• Staphylococcal carriage (or colonization) refers to the asymptomatic carriage of Staphylococcus aureus on a person's skin or mucous membranes.
• There are three patterns of S. aureus carriage:
  • Intermittent carriers.
  • Persistent carriers — have higher S. aureus loads and are at higher risk of getting S. aureus infections.
  • Non-carriers.
• The most common site of colonization by S. aureus is the nose. Other sites include the axillae, groin, hands, perineum, and pharynx.  
• The treatment of staphylococcal carriage is known as staphylococcal decolonization.

[Blaser, 2010; Craft, 2012; Verhoeven, 2014; Mehraj, 2016; Sakr, 2018]

How common is staphylococcal carriage?

• The prevalence of nasal carriage of Staphylococcus aureus is unclear, as the studies carried out have produced different findings, at least in part due to differing definitions of the categories of carriage. However, overall, the data suggest:
  • Up to 37% of people are persistent nasal carriers of S. aureus.
  • Up to 69% of people are intermittent carriers.
• Nasal carriage has been reported in: 
  • 10–15% of infants younger than 1 year of age — nasal colonization may occur within the first few days of life, with isolated strains usually identical to those found in the mother.
  • 38% of college students.
  • 50% of hospital physicians and military trainees.

[Craft, 2012; Mehraj, 2016; Sakr, 2018]

What are the risk factors for staphylococcal carriage?

• Factors that may increase the risk of Staphylococcus aureus carriage include:
  • Being a healthcare worker.
  • Age under 30 or over 60 years.
  • Male sex.
  • Skin disease, such as atopic dermatitis and psoriasis.
  • Health conditions such as HIV infection, diabetes mellitus, and liver dysfunction.
  • Obesity.
  • The use of hormonal contraception.
  • Recent antibiotic use.
  • Intravenous drug use.
  • A history of hospitalization or medical intervention (such as dialysis).
  • A household member being colonized.
  • Working with animals and livestock.

[Craft, 2012; Verhoeven, 2014; Mehraj, 2016; Sakr, 2018]

What are the complications of staphylococcal carriage?

• Complications of staphylococcal carriage include:
  • Skin and soft tissue infections, such as impetigo, boils, and cutaneous abscess [Patel, 2015; Sakr, 2018].
  • Surgical site infections [Sakr, 2018].
  • Recurrent skin and soft tissue infections — recurrence rates are higher in people with staphylococcal carriage [Ibler, 2014; Verhoeven, 2014].
  • Invasive infections. These are rare, and include bacteraemia, sepsis, endocarditis, osteomyelitis, and septic arthritis [Wertheim, 2005; Patel, 2015; Mehraj, 2016].
  • Nosocomial infections. Nasal carriage of Staphylococcus aureus has been shown to be a risk factor in the development of nosocomial infections, such as S. aureus sepsis [Verhoeven, 2014; Mehraj, 2016].
• Panton-Valentine leukocidin S. aureus (PVL-SA) is rarely isolated from nasal samples but is associated with recurrent boils and carbuncles, and serious complications including necrotizing pneumonia, necrotizing fasciitis, osteomyelitis, septic arthritis, and purpura fulminans [HPA, 2008; Mehraj, 2016].

Basis for recommendation

This information on the diagnosis of boils is based on expert opinion in medical textbooks [Hay, 2004a; Craft, 2012], the guideline Folliculitis and boils (furuncles/carbuncles) from the Primary Care Dermatological Society [PCDS, 2018], and review articles [Ladhani, 2005; Riain, 2013; Sukumaran and Senanayake, 2016].

Basis for recommendation

The information on diagnosis of a carbuncle is based on expert opinion in medical textbooks [Hay, 2004a; Craft, 2012], review articles [Ladhani, 2005; Riain, 2013; Troxell, 2020], and Practice guidelines for the diagnosis and management of skin and soft-tissue infections published by the Infectious Diseases Society of America [Stevens, 2014a].

Basis for recommendation

Information on the differential diagnoses of boils and carbuncles is based on expert opinion from textbooks and review articles, which collectively provide details about the clinical features of atypical mycobacteria infections [Yates, 2004], cystic acne [Craft, 2012; Troxell, 2020], dental abscess and osteomyelitis [Craft, 2012; Troxell, 2020], epidermoid cyst [Pugh, 2000; MacKie, 2004], folliculitis [Sladden, 2004], hidradenitis suppurativa [Layton, 2010; Ibler, 2014; Troxell, 2020], ecthyma and anthrax [Hay, 2004a], kerion [Pugh, 2000; Hay, 2004b], myiasis [Diaz, 2010], and orf [Sterling, 2004; Warrell, 2010; Troxell, 2020].

When should I admit or refer a person with a boil or carbuncle?

• Assess for the presence of discharging pus and fluctuance.
  • In early infection, it may be difficult to decide whether pus is present.
• Arrange for urgent same-day incision and drainage for:
  • All large and/or fluctuant boils.
    • Small boils will usually drain spontaneously after application of moist heat. See Acute boils or carbuncles.
  • All carbuncles.
• Incision and drainage may sometimes be performed in primary care if the lesion is small and the expertise and facilities are available. Otherwise, the person should be referred to a surgical unit or emergency department, according to local protocol.
  • If incision and drainage are carried out in primary care, the lesion should be covered with a sterile dressing afterwards, as this helps to prevent autoinoculation. Consider taking swabs of pus from the lesion and initiating antibiotic therapy, depending on clinical judgement.
• Consider admission for intravenous antibiotics if the person:
  • Is systemically unwell.
  • Has cellulitis. For more information, see the CKS topic on Cellulitis - acute.
  • Has an infection in an area where complications can be serious (such as the face).
  • Is immunocompromised as a result of an underlying disease (such as diabetes) or medication (such as corticosteroids).

When should I take a swab from a person with a boil or carbuncle?

• Consider taking a swab of pus from the contents of the lesion if:
  • The boil or carbuncle is:
    • Not responding to treatment.
    • Persistent or recurrent, to exclude atypical mycobacteria or Panton-Valentine leukocidin Staphylococcus aureus (PVL-SA).
  • There are multiple lesions.
  • The person:
    • Is immunocompromised.
    • Is known to be colonized with MRSA.
    • Has diabetes.
    • Is a member of a household, or resides in an institutional setting, where recurrent outbreaks of skin and soft tissue infections have been reported (to exclude PVL-SA).
• If PVL-SA is suspected, this should be mentioned specifically on the laboratory form.

How should I manage a person in primary care?

For people not requiring referral or admission:

• Advise them: 
  • To apply moist heat three to four times a day to alleviate pain, localize the infection, and hasten the drainage of pus. 
  • That a small boil may drain spontaneously — once this has occurred, the lesion should be covered with a sterile dressing to help prevent autoinoculation.
  • To seek medical advice if the lesion becomes fluctuant, as it may require incision and drainage.
  • To seek urgent medical advice if they become systemically unwell or develop cellulitis.
• Seek specialist advice if there is a possibility or confirmation of:
  • PVL-SA — suspect particularly in people with severe or recurrent boils, or who reside in a household or institutional setting (such as a care home or prison) where outbreaks of boils/carbuncles have been noted.
  • MRSA — suspect if the person has been hospitalized within the last year, has a chronic illness requiring healthcare visits, has a history of MRSA infection, resides in an institutional setting, or has had contact with a person known to have MRSA.
• Prescribe a course of oral antibiotics if the person:
  • Has a fever.
  • Has cellulitis (see the CKS topic on Cellulitis - acute).
  • The lesion is on the face.
  • Is in pain or severe discomfort.
  • There are other comorbidities (such as diabetes or immunosuppression).
    • Flucloxacillin is recommended first line (erythromycin [preferred in pregnancy and breastfeeding] or clarithromycin are alternatives if the person has a true allergy to penicillin). For further information on prescribing antibiotics, see prescribing information.
• Give information and self-care advice. Offer written information, such as the British Association of Dermatologists' patient information leaflet on boils. Advise the person to:
  • Take paracetamol or ibuprofen as required for pain relief. For more information, see the CKS topics on Analgesia - mild-to-moderate pain and NSAIDs - prescribing issues.
  • Maintain good personal hygiene.
  • Wash hands carefully after contact with lesions.
  • Wash and tumble dry underclothes, bed linen, and towels at a high temperature daily (if possible) to prevent spreading the infection to other parts of their body, or to other people.
  • Use a separate face cloth and towel.
  • Wear loose-fitting, lightweight clothes as much as possible.
  • Keep wounds or grazes clean and covered with sterile gauze until they heal.
  • Seal and discard used gauze or dressings immediately. If purulent drainage collects, gauze or dressings should be changed frequently.
  • Not participate in contact sports, or visit a swimming pool or gym until the boil has cleared, to avoid passing the infection on to others.

How should I manage recurrent boils and carbuncles?

• Exclude and manage other underlying causes where appropriate, for example:
  • Diabetes. For further information, see the CKS topics on Diabetes - type 1 and Diabetes - type 2.
  • Anaemia and blood dyscrasias. For further information, see the CKS topics on Anaemia - iron deficiency and Polycythaemia/erythrocytosis.
  • Obesity. For further information, see the CKS topic on Obesity.
  • Skin disease (such as eczema). For further information, see the CKS topic on Eczema - atopic.
  • Localized predisposing factors (such as pressure from tight clothing).
  • Treatment with corticosteroids or other immunosuppressive drugs.
• Ask the person whether they have had close personal contact with an infected person, such as a family member, or through contact sports.
• Ask the person whether they or a family member works in a hospital or other healthcare setting, as recurrence could be due to staphylococcal carriage.
• Swab the lesion (to confirm the causative organism and antibiotic sensitivities) and treat with the appropriate antibiotic for 7 days. For futher information, see the section on Acute boils and carbuncles.
• If PVL-SA infection is suspected, specifically mention this on the laboratory form. 
  • If staphylococcal infection is confirmed, check for carriage of S. aureus and manage accordingly. See Scenario: Staphylococcal carriage.
  • If the person is already known to have MRSA infection or the swab sample of pus grows MRSA, see the CKS topic on MRSA in primary care for further information.
  • If PVL-SA infection is confirmed, management should be discussed with microbiology or the local infection control team.
• Reinforce self-care advice where appropriate.

How should I swab for staphylococcal carriage?

• Where staphylococcal carriage is suspected:
  • Take swabs from the contents of the boil or carbuncle.
  • If recurrent boils or carbuncles are localized to the facial area, swab the nasal cavity.
  • If the boils or carbuncles are more extensive, consider swabbing the perineum, groin, axillae, and umbilicus in addition to the nose. 

How should I decolonize a person with confirmed staphylococcal carriage?

• Do not start decolonization until acute infection has resolved.
• Ensure that the person understands preventative measures to reduce the risks of future infections following decolonization.
• Eliminate nasal carriage by prescribing Naseptin^® cream (chlorhexidine plus neomycin), four times a day for 10 days. Be aware that Naseptin^® contains arachis oil (peanut oil) and should not be used by a person known to be allergic to peanuts or soya.
  • If Naseptin^® cream is unsuitable or not effective, consider prescribing mupirocin nasal ointment, three times daily for 5 days.
    • Note: Naspetin^® has recently been reformulated and no longer contains arachis oil (peanut oil). However, if this is prescribed, advise people to check the formulation before using as the previous formulation may still be in the supply chain.   
  • If both mupirocin and Naseptin^® are ineffective, seek expert advice.
• If the person has a confirmed PVL skin infection, discuss their management with microbiology or the local infection control team.
• All people requiring decolonization should be advised about treatment for the skin:
  • Use an antiseptic preparation (such as chlorhexidine 4% body wash/shampoo or Triclosan 2%) daily as liquid soap in the bath, shower, or sink for 5 days.
    • Avoid diluting beforehand in water as this will reduce its efficacy.
    • Apply directly to wet (never dry) skin on a disposable wipe or by using the hand.
    • Allow it to remain on the skin for about 1 minute.
    • Rinse off thoroughly and dry skin well.
    • Additionally, use as a shampoo on the first, third, and fifth day.
    • Avoid using regular soap in addition to the antiseptic during baths/showers.
    • Pay particular attention to the axillae, groins, buttocks, under the breasts, and the hands.
• If a person with a dermatological condition, such as eczema, requires treatment for the skin, seek a dermatological opinion.
• Whilst the skin treatment is being used for 5 days, advise the person to reduce the household spread of staphylococcus by:
  • Changing sheets and towels daily. Wash sheets, towels, and underwear regularly on a hot wash cycle (above 55°C). The clothes should be turned inside out and the machine not overloaded so that the water can circulate.
  • Vacuuming and dusting regularly, particularly in the bedrooms.
  • Using pump-action liquid soap and avoiding bar soaps.
  • Using his or her own towel and flannel, and rinsing the flannel in hot water before use.
  • Cleaning the sinks and bath with a disposable cloth and detergent after use and rinsing clean.

What should I do if there is still recurrence of boils or carbuncles despite treating staphylococcal carriage?

• Enquire about whether any family member is a hospital or healthcare worker.
• If there are recurrent boils or carbuncles consider:
  • Excluding underlying causes.
  • Extending swabbing to exclude carriage at other sites such as perineum, groin, axillae, and umbilicus, if only the nose was initially swabbed.
  • Specifically requesting testing for PVL-SA.
  • Identifying and treating potential sources of infection in the family and close contacts.
  • Screening household members if they are willing to co-operate with an eradication strategy. However, this may be difficult to organize in primary care.
• If the person has MRSA, see the CKS topic on MRSA in primary care for further information.
• If the person has PVL-SA infection, discuss with microbiology or the local infection control team.

What should I advise about prevention of further staphylococcal reinfection?

• Advise the person to:
  • Take a daily shower or bath.
  • Wash hands regularly with soap and water.
  • Change clothes and underclothes regularly.
  • Avoid sharing towels, face cloths, razors, toothbrushes, and water bottles.
  • Wash sports clothes after use each time.
  • Use disposable tissues to blow their nose and avoid picking their nose.
  • In saunas and gyms, to sit on a clean towel and wash the towel after use.

Dose

• Adults: 250–500 mg four times daily for 5–7 days.
• Children aged:
  • 1 month to 1 year: 62.5–125 mg four times daily for 5–7 days.
  • 2–9 years: 125–250 mg four times daily for 5–7 days.
  • 10–17 years: 250–500 mg four times daily for 5–7 days.

[BNF, 2024]

Contraindications and cautions

• Do not prescribe flucloxacillin to people with:
  • A true penicillin allergy — gastrointestinal adverse effects alone (for example nausea, vomiting, or diarrhoea) do not constitute an allergy to penicillin.
  • History of flucloxacillin-associated jaundice or hepatic dysfunction.
• Prescribe flucloxacillin with caution to people with: 
  • Hepatic dysfunction (not flucloxacillin-related), especially if they are 50 years of age or older, or have a serious underlying medical condition.
  • Severe renal impairment — reduce the dose if the person's estimated glomerular filtration rate (eGFR) is less than 10 mL/minute/1.73 m².

[ABPI, 2021a; BNF, 2021]

Adverse effects

• Diarrhoea is a common adverse effect of flucloxacillin.
  • Consider pseudomembranous colitis if a person develops severe diarrhoea during or after treatment with flucloxacillin.
  • Pseudomembranous colitis is an acute, exudative colitis caused by Clostridium difficile, a Gram-positive toxin-releasing bacillus. It often follows antibiotic treatment. For more information, see the CKS topic on Diarrhoea - antibiotic associated.
• Cholestatic jaundice and hepatitis may occur (very rarely) up to several weeks after treatment with flucloxacillin has been stopped. Risk factors include treatment for more than 2 weeks and increasing age.

[ABPI, 2021a; BNF, 2021]

Drug interactions

• Methotrexate — methotrexate clearance may be reduced, causing an increased risk of toxicity, however, serious interactions are uncommon. 
  • Standard routine monitoring will identify any decreases in elimination in people on high-dose regimens. For people on low-dose regimens, consult local or national guidelines/protocols for monitoring and management.
• Coumarin and indanedione anticoagulants (warfarin, phenidione) — consider increased monitoring of international normalized ratio (INR) and adjust the dose accordingly.
• Posaconazole, voriconazole — concentrations of antifungal is greatly decreased. If concurrent use is unavoidable, monitor for decreased efficacy and consider increasing the dose of the azole (although this may not resolve the issue). 
• Probenecid — concomitant administration may result in increased levels of flucloxacillin.
• Live cholera vaccine — efficacy of vaccine may be reduced. Avoid flucloxacillin from 14 days before to 10 days after receiving live cholera vaccine.
• Live typhoid vaccine — immune response to vaccine may be reduced. Avoid flucloxacillin from 3 days before to 3 days after receiving live typhoid vaccine.

[Preston, 2023]

Dose

• Adults: 250–500 mg twice daily for 5–7 days.
• Children aged:
  • 1 month to 11 years with body weight:
    • Less than 8 kg: 7.5 mg per kg twice daily for 5–7 days.
    • 8–11 kg: 62.5 mg twice daily for 5–7 days.
    • 12–19 kg: 125 mg twice daily for 5–7 days.
    • 20–29 kg: 187.5 mg twice daily for 5–7 days.
    • 30–40 kg: 250 mg twice daily for 5–7 days.
  • 12 years and over:  250–500 mg twice daily for 5–7 days.

[BNF, 2024]

Contraindications and cautions

• Do not prescribe clarithromycin to people with:
  • Known hypersensitivity to clarithromycin or other macrolide antibiotics.
  • A history of QT prolongation (congenital or acquired) or ventricular arrhythmia, including Torsade de Pointes.
  • Hypokalaemia.
  • Severe hepatic failure in combination with renal impairment.
• Clarithromycin is also contraindicated for people taking certain drugs. 
• Prescribe clarithromycin with caution in people with:
  • Coronary artery disease, severe cardiac insufficiency, conduction disturbances, or clinically relevant bradycardia — increased risk of QT prolongation.
  • Impaired hepatic function (or people concomitantly receiving potentially hepatotoxic drugs) — clarithromycin is principally excreted by the liver. Hepatic dysfunction including increased liver enzymes and cholestatic hepatitis (with or without jaundice) has been rarely reported with clarithromycin.
  • Moderate to severe renal impairment — use half the dose if the estimated glomerular filtration rate (eGFR) is less than 30 mL/min/1.73 m². Avoid Klaricid XL^® (clarithromycin 500 mg prolonged-release once daily tablets) or other modified-release clarithromycin preparations in people with an eGFR less than 30 mL/min/1.73 m². 
  • Conditions that predispose to QT interval prolongation, such as electrolyte disturbances (for example hypomagnesemia) and people taking drugs that prolong the QT interval — macrolides can also prolong the QT interval, increasing the risk of Torsades de Pointes arrhythmia. 
  • Myasthenia gravis — macrolide antibiotics may aggravate weakness symptoms of people with myasthenia gravis.

[EMC, 2025a; ABPI, 2021b; ABPI, 2021c; BNF, 2021]

Adverse effects

• Clarithromycin is generally well tolerated. 
• The most common adverse effects are gastrointestinal — such as nausea, vomiting, dyspepsia, and diarrhoea.
  • Consider pseudomembranous colitis if a person develops severe diarrhoea during or after treatment with clarithromycin.
  • Pseudomembranous colitis is an acute, exudative colitis caused by Clostridium difficile, a Gram-positive toxin-releasing bacillus. It often follows antibiotic treatment. For more information, see the CKS topic on Diarrhoea - antibiotic associated.
• Less common adverse effects include rash and hepatoxicity.
• Very rarely, QT prolongation, ventricular tachycardia, and Torsade de Pointes arrhythmia have been reported.

[EMC, 2025a; BNF, 2021]

Drug interactions

• Drug interactions with clarithromycin include:
  • Pimozide — do not prescribe with clarithromycin as concurrent use may result in QT prolongation, cardiac arrhythmias including ventricular tachycardia, ventricular fibrillation, and Torsade de Pointes.
  • Ergotamine and dihydroergotamine — do not prescribe with clarithromycin as concurrent use may result in acute ergot toxicity. 
  • Colchicine — avoid concomitant administration.
  • Carbamazepine — monitor carbamazepine levels within 3–5 days of starting clarithromycin, and adjust dose accordingly. Clarithromycin can increase carbamazepine levels, causing carbamazepine toxicity (may present as nausea and vomiting, ataxia, and drowsiness).
  • Edoxaban — manufacturer advises caution with concurrent treatment with edoxaban, particularly in those with a high risk of bleeding.
  • Ivabradine — concomitant treatment is contra-indicated, owing to CYP3A4 inhibition by clarithromycin which can cause elevated levels of ivabradine.
  • Other drugs that prolong the QT interval — if possible, avoid giving clarithromycin to a person who is already taking a drug that can potentially prolong the QT interval.
  • Ranolazine — avoid concomitant administration. Clarithromycin possibly increases plasma concentrations of ranolazine.
  • Ticagrelor — avoid concomitant administration. Clarithromycin possibly increases the plasma concentration of ticagrelor.
  • Statins — there is an increased risk of myopathy.
    • For simvastatin — do not prescribe clarithromycin to a person taking simvastatin. Consider temporarily stopping simvastatin during short-term treatment with clarithromycin. 
    • For atorvastatin — avoid concurrent use with clarithromycin if possible. Consider temporarily stopping atorvastatin during short-term treatment with clarithromycin. If concurrent use cannot be avoided, prescribe the lowest starting dose of atorvastatin (10 mg), and advise the person to report any muscle pain, tenderness, or weakness.
    • For pravastatin — prescribe clarithromycin with caution and advise the person to seek medical advice if they experience symptoms of myopathy (for example muscle pain, tenderness, or weakness).
    • Other statins — clinically significant interaction with clarithromycin is not expected for rosuvastatin and fluvastatin. Nevertheless, advise the person to report any muscle pain, tenderness, or weakness. 
  • Warfarin — increase monitoring of the international normalized ratio (INR) when both drugs are used (particularly in elderly people), and adjust the warfarin dose accordingly. Clarithromycin may enhance the effect of warfarin. 
  • Oral hypoglycaemic drugs and insulin — the concurrent use of clarithromycin and antidiabetic drugs (such as sulphonylureas and/or insulin) can result in significant hypoglycaemia.
    • Monitor blood glucose levels more regularly and adjust the antidiabetic drug (and/or insulin) dose accordingly. 
  • Calcium channel blockers (CCBs) — due to an increased risk of hypotension, caution is advised with the concurrent use of clarithromycin and CCBs metabolized by CYP3A4 (such as verapamil, amlodipine, and diltiazem).
  • Drugs that cause hypokalaemia (such as diuretics, corticosteroids, short-acting beta-2 agonists) — hypokalaemia is a risk factor for QT prolongation.
  • Oral hormonal contraception — additional contraceptive precautions are not required during or after courses of clarithromycin.
    • However, women should be advised about the importance of correct contraceptive practice if they experience vomiting or diarrhoea. For further information, see the CKS topic on Contraception - assessment.

[CoSRH, 2019; BNF, 2021; Preston, 2021; EMC, 2024]

Doses

• Adults: 250–500 mg four times daily for 5–7 days.
• Children aged:
  • 1–23 months: 125 mg four times daily for 5–7 days.
  • 2–7 years: 250 mg four times daily for 5–7 days.
  • 8–17 years: 250–500 mg four times daily for 5–7 days.

[BNF, 2024]

Contraindications and cautions

• Do not prescribe erythromycin to people with:
  • Porphyria or a known hypersensitivity to erythromycin.
  • A history of QT interval prolongation or ventricular cardiac arrhythmia.
  • Conditions that predispose to QT interval prolongation such as electrolyte disturbances and people taking drugs that prolong the QT interval — macrolides can also prolong the QT interval, increasing the risk of Torsades de Pointes arrhythmia.
• Prescribe erythromycin with caution in people with:
  • Impaired hepatic function (or people concomitantly receiving potentially hepatotoxic drugs) — erythromycin is principally excreted by the liver. 
  • Renal impairment — give a maximum of 1.5 g daily in severe renal impairment due to the risk of ototoxicity. 
  • Myasthenia gravis — macrolide antibiotics may aggravate weakness symptoms of people with myasthenia gravis.

 [EMC, 2025b; MHRA, 2020; BNF, 2021]

Adverse effects

• Gastrointestinal adverse effects such as nausea, vomiting, and diarrhoea are common in people taking erythromycin.
  • Consider pseudomembranous colitis if a person develops severe diarrhoea during or after treatment with erythromycin.
  • Pseudomembranous colitis is an acute, exudative colitis caused by Clostridium difficile, a Gram-positive toxin-releasing bacillus. It often follows antibiotic treatment. For more information, see the CKS topic on Diarrhoea - antibiotic associated.
• Hepatic dysfunction including increased liver enzymes and cholestatic hepatitis (with or without jaundice) has been rarely reported with this drug.

[EMC, 2025b; BNF, 2021]

Drug interactions

• Drug interactions with erythromycin include:
  • Tolterodine, mizolastine, amisulpride, domperidone, ergotamine, dihydroergotamine, or pimozide — concurrent administration with erythromycin is contraindicated.
  • Cimetidine — monitor concurrent use closely as a dose reduction of erythromycin may be necessary. Cimetidine may inhibit the metabolism of erythromycin, leading to an increased plasma concentration.
  • Calcium channel blockers (CCBs) — due to an increased risk of hypotension, caution is advised with the concurrent use of erythromycin and CCBs metabolized by CYP3A4 (such as verapamil).
  • Colchicine — avoid concurrent use if possible. Colchicine toxicity has been reported following concomitant use with erythromycin.
  • Carbamazepine — avoid concurrent use unless carbamazepine levels can be closely monitored and suitable dose reductions made. Erythromycin can increase carbamazepine levels by as much as five-fold, causing carbamazepine toxicity (which may present as nausea and vomiting, ataxia, and drowsiness).
  • Corticosteroids — levels of corticosteroids may be increased. Monitor for corticosteroid adverse effects (such as moon face, weight gain, hyperglycaemia), and adjust the corticosteroid dose or stop the macrolide as appropriate. 
  • Drugs that prolong the QT interval — if possible, avoid giving erythromycin to a person who is already taking a drug that can potentially prolong the QT interval.
  • Lomitapide — concurrent use with erythromycin increases transaminase levels and is contraindicated.
  • Statins — there is an increased risk of myopathy.
    • For simvastatin — do not prescribe erythromycin to a person taking simvastatin. Consider temporarily stopping simvastatin during short-term treatment with erythromycin. 
    • For atorvastatin — avoid concurrent use with erythromycin if possible. Consider temporarily stopping atorvastatin during short-term treatment with erythromycin. If concurrent use cannot be avoided, prescribe the lowest starting dose of atorvastatin (10 mg), and advise the person to report any muscle pain, tenderness, or weakness.
    • For pravastatin — prescribe erythromycin with caution and advise the person to seek medical advice if they experience symptoms of myopathy (for example muscle pain, tenderness, or weakness).
    • Other statins — clinically significant interaction with erythromycin is not expected for rosuvastatin and fluvastatin. Nevertheless, advise the person to report any muscle pain, tenderness, or weakness. 
  • Theophylline — consider using clarithromycin (in preference to erythromycin) as clarithromycin normally causes only modest (clinically unimportant) increases in theophylline levels.
    • Concurrent use of erythromycin with high doses of theophylline may be associated with an increase in serum theophylline levels and potential theophylline toxicity (which may present as palpitations, nausea, tremor, and headache). If this is suspected, reduce the dose of theophylline. 
    • Concurrent treatment may also result in a significant decrease in erythromycin serum concentrations, leading to sub-therapeutic concentrations of erythromycin.
  • Rivaroxaban — erythromycin may increase levels of rivaroxaban, increasing the risk of bleeding. 
  • Warfarin — monitor the international normalized ratio (INR) when both drugs are used (particularly in elderly people), and adjust the warfarin dose accordingly. Erythromycin may enhance the effect of warfarin; this is an established but unpredictable interaction.
  • Zopiclone — monitor concurrent use. Erythromycin has been reported to decrease the clearance of zopiclone and this may lead to an increase in the effects of zopiclone. 
  • Oral hormonal contraception — additional contraceptive precautions are not required during or after courses of erythromycin.
    • However, women should be advised about the importance of correct contraceptive practice if they experience vomiting or diarrhoea. For further information, see the CKS topic Contraception - assessment.

[CoSRH, 2019; EMC, 2025b; MHRA, 2020; Preston, 2021]