Previous changes

March 2022 — reviewed. A literature search was conducted in March 2022 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials (RCTs) published since the last revision of the topic. 

April to June 2017 — reviewed. Literature searches were conducted in April 2017 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of this topic. Changes include:

• A section on agents involved in poisoning and overdose has been added. 
• Clinical situations where poisoning is a possibility and information about toxidromes (the syndrome of signs and symptoms caused by certain classes of substances, usually in overdose) have been added. 
• The assessment of a person who has been poisoned has been revised in line with expert opinion in review articles and in the British National Formulary. 
• The recommendations on when to admit someone who has been poisoned have been revised in line with guidelines from the National Institute for Health and Clinical Excellence on  Self-harm: longer-term management (2011) and the Royal College of Psychiatrists on Managing self-harm in young people (2014) and expert advice in the British National Formulary.
• There have been minor changes on how to assess capacity in emergency situations.

May 2012 — revised. A literature search was conducted in April 2012 to identify evidence-based guidelines, UK policy, systematic reviews, and key RCTs published since the last revision of the topic. No changes to clinical recommendations have been made. The topic has has undergone minor structural changes to improve clarity and navigation, and information on assessing a person's capacity has been added.

July 2007 — minor update to text. The section on admission to hospital for people who refuse has been reworded, to highlight the difference between the use of common law and the Mental Health Act. Minor typographical correction made to the Clinical Summary. Issued in August 2007.

March to July 2007 — converted from CKS guidance to CKS topic structure. The evidence-base has been reviewed in detail, and recommendations are more clearly justified and transparently linked to the supporting evidence. This CKS topic also provides information on admission criteria for poisonings and what do to if someone refuses to go to hospital (against medical advice).

July 2006 — minor update. Revised information regarding the National Poisons Information Service (NPIS). Issued in July 2006.

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

August 2004 — updated to include National Institute for Health and Care Excellence recommendations for the short-term management of self-harm. Issued September 2004.

November 2003 — reviewed. Validated in March 2004 and issued in June 2004.

March 2001 — reviewed. Validated in March 2001 and issued in June 2001.

March 2000 — rewritten.

August 1997 — written, replacing previous guidance called Accidental poisoning by drugs; Other poisoning — non drug; Poisoning — animal or plant venom.

New evidence

Evidence-based guidelines

No new evidence-based guidelines since 1 March 2022.

HTAs (Health Technology Assessments)

No new HTAs since 1 March 2022.

Economic appraisals

No new economic appraisals relevant to England since 1 March 2022.

Systematic reviews and meta-analyses

No new systematic reviews or meta-analysis which reach the CKS threshold for inclusion since 1 March 2022.

Primary evidence

No new primary evidence which reaches the CKS threshold for inclusion published since 1 March 2022.

New policies

No new national policies or guidelines since 1 March 2022.

New safety alerts

No new safety alerts since 1 March 2022.

Changes in product availability

No changes in product availability since 1 March 2022.

Basis for recommendation

This information is based on expert opinion in narrative reviews Initial management of suspected poisoning in children and young people [Anderson, 2021], Principles of assessment and diagnosis of the poisoned patient [Thanacoody, 2020a], Assessment and diagnosis of the poisoned patient [Vale, 2016], Is the cause toxicological? [Thomas, 2016], and the British Medical Journal (BMJ) Best Practice guide Toxic ingestions in children [BMJ, 2021a].  

Basis for recommendation

These recommendations are based on expert opinion in a narrative review Principles of assessment and diagnosis of the poisoned patient [Thanacoody, 2020a], the British Medical Journal (BMJ) Best Practice guides Paracetamol overdose in adults [BMJ, 2020], Toxic ingestions in children [BMJ, 2021a], the National Institute for Health and Care Excellence (NICE) guideline Self-harm in over 8s: short-term management and prevention of recurrence [NICE, 2004], the British National Formulary (BNF) [BNF, 2022], and the toxicology database TOXBASE [TOXBASE, 2022].

• It is recommended that paracetamol levels are checked for people who present with features consistent with opioid poisoning, and for unconscious people or people with reduced consciousness where drug overdose is a possibility [NICE, 2004; Thanacoody, 2020a].  
• For more detailed information on toxidromes, see the TOXBASE information on Poisoning with an unknown substance [TOXBASE, 2022].

How should I assess a person who is suspected of being poisoned or taking an overdose?

• Most people should be seen (in person) after a poisoning episode or overdose.
  • Advice may be offered over the telephone (without seeing the person) if the healthcare professional feels confident that the poisoning episode is not serious. For sources of information regarding the management of poisoning, see Information sources. 
• If the person has collapsed and is unresponsive ensure the airway is open (in the absence of trauma) and check for normal breathing. If they are not breathing normally, start cardiopulmonary resuscitation (CPR) immediately, and call for an ambulance. 
• Assess the person's overall status using the ABCDE approach.
  • Perform a rapid assessment of the airway — remove any obstructions, assess evidence of any injury (for example from ingestion of a corrosive substance), and secure a patent airway.  
  • Assess the person's consciousness — the Glasgow coma scale is the method most commonly used.
  • Measure respiratory rate — if a pulse oximeter is available, measure oxygen saturations.
    • Note this may not be accurate if there is poor peripheral perfusion, or carboxyhaemoglobin or methaemoglobin. 
  • Measure the person's pulse, blood pressure and temperature.  
• Arrange emergency transfer to hospital following the immediate assessment of the person if:  
  • The person is unconscious or has a reduced level of consciousness. 
  • There is a reduced respiratory rate or oxygen saturation is reduced. 
  • There is hypotension. 
  • There is tachycardia or bradycardia or an irregular pulse. 
  • There is hypothermia or hyperthermia.
  • The person has had a seizure. 
  • There are any other concerning clinical features, or the person's condition is deteriorating.
• If emergency transfer is not required, take a history and ask the person (or friends, family members, or other health professionals if appropriate):
  • What substance was taken — the amount, if any other medicines have been taken, and alcohol use.
    • Note that the person's account of what and how much has been taken may not be accurate if they have impulsively ingested what is available, and they may estimate quantities in terms of mouthfuls, or handfuls. This can result in inconsistency between an unreliable history and laboratory blood and urine tests. It may be useful to prompt them to recall quantities in terms of strips or packets of drugs.
  • When it was taken — try to establish the exact timing(s) of ingestion or contact (a single acute overdose, staggered or chronic). This is especially important in paracetamol poisoning. 
  • About the route of administration (mouth, inhalation, or injection). 
  • Why the substance was taken — if it was accidental, deliberate or a therapeutic error.
    • If there is a risk of repetition.
    • People who have self-harmed will need a further psychosocial assessment by another trained specialist (mental health worker, social worker) after the treatment of their physical problems. 
  • About other relevant details, such as age, weight, sex, medical history (including psychiatric history and history of self-harm), medication and factors that will affect the excretion or metabolism of the poison, such as renal or hepatic impairment.
  • About any symptoms they may be experiencing, depending upon the substance(s) involved. See the section on Symptoms and signs of drugs that are commonly involved in poisoning or overdose. 
• Perform an examination, depending on the clinical situation. This may include:
  • General observations — presence of track marks may indicate intravenous drug misuse, alcohol or solvents on the breath and stigmata of liver disease can suggest alcohol dependence, atypical bruising or fractures may raise safeguarding concerns, and skin blisters may be found in people who are, or have been, unconscious due to poisoning. 
  • A neurological examination (including pupils and eye movements).
    • Abnormal movements — assess for acute dystonic movements (which can occur after exposure to antidopaminergics, such as antipsychotics), hypertonia, hyperreflexia, and extensor plantar response (which can occur after tricyclic antidepressant poisoning). 
    • Pupil size and reaction — widely dilated pupils that react poorly to light be due to agents with anticholinergic activity (for example tricyclic antidepressants), or sympathomimetic activity (for example, amfetamines). Pinpoint pupils (miosis) occur after exposure to opioids or agents with cholinergic activity (for example, pesticides).
    • Eye movements — strabismus, internuclear ophthalmoplegia, dysconjugate roving eye movements and total external ophthalmoplegia may be seen in poisoning with tricyclic antidepressants, barbiturates, phenothiazines and anticonvulsants such as phenytoin and carbamazepine.
    • Visual acuity and visual fields — blurring, loss of vision and tunnel vision may occur with some drugs (for example, quinine poisoning). 
  • Check for signs that are consistent with the poison or drug that has been taken, or if the poison is not known, compare the person's symptoms and examination findings to those commonly associated with known poisons, see toxidromes in the section on Symptoms and signs of drugs that are commonly involved in poisoning or overdose. 
• If the person has deliberately self-poisoned:
  • Conduct a preliminary psychosocial assessment — determine the person's mental capacity, their willingness to remain for further (psychosocial) assessment, their level of distress and the possible presence of mental illness.
    • Where possible, the person should be seen alone for this assessment, to maintain confidentiality and allow the person to discuss any problems between themselves and friends or family. 
  • Assess the likely physical risk, the person's emotional and mental state, and the risk of further self-harm or suicide — identify the main clinical and demographic features and psychological characteristics associated with risk, in particular depression, hopelessness and continuing suicidal intent. 
    • Communicate the outcome of these assessments to other healthcare professionals who are involved in the person's care. 
    • For more information about an initial risk assessment in people who have self-poisoned, see the CKS topic on Self-harm.
  • Assess any safeguarding concerns — this applies to people of all ages, including adults, older people, children and young people. It includes consideration of risks to the person who has self-harmed, any children or adults in the person's care and to other family members or significant others. For further information, see the CKS topic on Child maltreatment. 
• Investigations are not routinely necessary or appropriate in primary care for those people who do not need emergency referral to hospital.
• Consult the poisons information database, TOXBASE, for information on the specific poison(s) involved, and manage accordingly. See the section on Information sources. 
• Telephone the NPIS for advice if: 
  • Poisoning is severe or complex (for example multiple ingestions).
  • The person has significant comorbidity.
  • There are any uncertainties regarding the person's management after consulting TOXBASE online.  
  • The poison is unknown.
• Telephone the UK Teratology Information Service (UKTIS) for advice if the person is pregnant. See the section on Information sources.  

What sources of information should I use to guide the management of a person who has been poisoned or taken an overdose?

Sources of information and advice include:

• TOXBASE (www.toxbase.org). 
  • This is a clinically-based toxicology database and the first-line source of information for healthcare professionals. It is regularly updated by the National Poisons Information Service (NPIS), and provides information about the diagnosis, treatment and management of patients exposed to drugs, household products, and industrial and agricultural chemicals. 
  • It is available through the TOXBASE website or a mobile app and is free to all UK NHS healthcare units and healthcare professionals.
  • A back-up site is available at www.toxbasebackup.org if the main site cannot be accessed.
• The Public Health England and NPIS information leaflet for healthcare professionals Low toxicity substances [NPIS, 2017]. 
• NPIS if there are complex cases or if there is any uncertainty about the degree of risk or management, for example: 
  • Severe or complex cases, including multiple ingestions. 
  • People with significant comorbidity. 
  • Cases where the poison is unknown. 
• The NPIS advice line gives information and advice to NHS staff to assist them in deciding whether a person needs admission or can be managed at home. It also provides advice on the hospital management of people requiring admission. 
  • The NPIS is a network of units commissioned by Public Health England for the UK health departments. 
  • The service is available 24 hours a day via the central UK number 0344 892 0111. It consists of a network of poisons information specialists based, supported by a team of on-call consultant clinical toxicologists attached to major teaching hospitals. 
  • The service helps to reduce unnecessary hospital referrals and improves the care of those at risk of serious complications. 
• In Northern Ireland, the Regional Medicines and Poison Information Service — this provides information during working hours. The NPIS takes out-of-hours enquiries. 
• UK Teratology Information Service (UKTIS) in the event of poisoning in a pregnant woman — see www.uktis.org, or call 0344 892 0909.
  • Information for healthcare professionals can be accessed online through TOXBASE, which contains the review documents produced by UKTIS on maternal exposures to drugs and chemicals, online through the UKTIS website, and by telephone.   
  • UKTIS is part of the NPIS and provides a national service on the safety of drugs and chemicals during pregnancy.
  • Patient information leaflets are available through the Bumps (best use of medicines in pregnancy) website http://www.medicinesinpregnancy.org.
• Medicines information services can provide advice on many aspects of medicines therapy
  • Primary care-based healthcare professionals in England can contact the Specialist Pharmacy Service for practical advice on when to restart drugs (if the person has taken additional doses accidentally or after acute toxicity has resolved), possible adverse effects, and can also direct healthcare professionals to further information (see Medicines Advice contact details – SPS - Specialist Pharmacy Service – The first stop for professional medicines advice).
  • Details of services in Northern Ireland, Scotland and Wales, plus hospital-based services can be found at UKMI Contacts.

When should I admit a person to hospital after an episode of poisoning or overdose?

• Consult TOXBASE for advice regarding the toxicity of a substance and whether the person requires admission. If there is any uncertainty after this, contact NPIS for advice, or discuss the case with a consultant from the nearest Accident and Emergency department. See the section on Information sources for further details.
  • Arrange urgent hospital admission if advised.
• Refer all people who have deliberately self-poisoned urgently to accident and emergency — the nature and quantity of the ingested substances may not be clearly known to the person who has self-poisoned, making accurate risk assessment difficult. 
  • If available, send a sample of the suspected drug(s) or poison into hospital with them. 
  • Arrange for the person to be accompanied by an appropriate person if there is a risk of further self-harm, reluctance of the person to attend, or the person is very distressed. 
  • Arrange follow-up after hospital discharge according to a mutually agreed plan to ensure ongoing management of the person's psychosocial needs and treatment for identified issues or risk of further self-harm or suicide. 
• Refer people who are symptomatic after taking or being exposed to a poison or drug urgently to hospital. 
  • Minor gastrointestinal upset alone is generally not considered an absolute indication for admission to hospital in people who have ingested a small amount of a substance considered to be of low toxicity — NPIS advises that a small glass of water (or milk or juice) may be given if there is mild gastrointestinal upset. 
• Refer people who have taken poisons with delayed action urgently to hospital, even if the person appears well and is asymptomatic. 
• Delayed-action medicines include aspirin, iron, paracetamol, tricyclic antidepressants, co-phenotrope, and all modified-release preparations.
• Note: salicylates may be present in some over-the-counter antacid preparations, and ingestion of topical liniments containing oil of wintergreen carries a high risk of salicylate poisoning — always consult TOXBASE for advice regarding the toxicity of a substance.
• Refer all people who have taken or been exposed to a drug that is unknown urgently to hospital.
• Consider admitting children, pregnant women, people with pre-existing comorbidities, or people taking concomitant medication, even if the drug is considered to have a good safety profile.
• In areas that are a significant distance away from an emergency department, and where there will likely be a delay in reaching hospital, consider initiating assessment and treatment in primary care following a discussion with the nearest Accident and Emergency consultant (for example, taking blood samples to test for paracetamol and other drugs).  
• Consider child neglect if there are repeated presentations of accidental ingestion of poisons in a child. For more information, see the CKS topic on Child maltreatment - recognition and management.

How should I manage a person who does not need admission to hospital?

• Access information about the substance on TOXBASE, and use this as a guide to the person's management.
• For people who have ingested a substance considered to be of low toxicity — hospital assessment is not usually indicated for accidental poisoning. Advise the person: 
  • That they may experience mild gastrointestinal upset, and that if this occurs, they should drink a small glass of water, milk or juice. 
    • See the NPIS leaflet, Low toxicity substances.
  • When to seek medical advice, for example if the gastrointestinal upset does not improve, becomes worse, or new symptoms develop. 
• For people who have ingested a considerable quantity of a low toxicity substance, or if the person has symptoms other than mild gastrointestinal upset following ingestion of a low toxicity substance, follow advice from TOXBASE.
  • Contact the NPIS if there are uncertainties after accessing TOXBASE, and refer the person to hospital if appropriate. 
• For people who have accidentally taken an additional tablet of their own medication — hospital assessment is not usually indicated.
  •  Consider:
    • The indications, maximum daily doses, toxic doses, adverse effects and interactions of the medicine. 
    • The person's past medical history (especially renal and liver impairment) and medication history.
    • The person's age and social circumstances.
  • Refer to the BNF or TOXBASE for information regarding individual medicines and the person's subsequent management. Seek advice where appropriate, for example a discussion with the medical consultant on call, or contact the UK Medicines Information (UKMI) service.
  • Refer people who have exceeded the daily dose of two or more cardio-toxic agents for hospital assessment irrespective of the dose ingested. 
  • Restart the person on their medication when appropriate.
    • Restarting medication may be complicated depending on the drug and dosing regimen. CKS cannot provide advice for individual drugs taken, due to the number of variables that must be considered.
    • If there is any uncertainty about when to restart medication after an additional tablet has been taken, seek further advice. See the section on Information sources. 
    • Consider the cause of the error (for example, poor memory or confusion) and whether steps need to be taken to avoid future errors, such as supervision of medication or provision of a dosette box.

How should I manage a person who refuses admission to hospital after a poisoning?

• If a person refuses to go to hospital, determine the reason(s) and provide information about the potential consequences of not receiving hospital treatment and assessment. 
• If the person still refuses admission, and this is felt to be in their best interests, assess their capacity, and consider whether a compulsory admission under The Mental Health Act, 1983 is appropriate. 
  • If possible, discuss this with the person's family, friends or carers taking into account the duty of confidentiality. 
  • If a person is judged to have diminished capacity and/or the presence of a significant mental health disorder, refer for urgent hospital admission or urgent mental health assessment, depending on clinical judgement.
    • Document why capacity is in doubt and record details of the assessment process and findings. 
  • If there is uncertainty about whether a person has capacity to make informed decisions, seek advice from a psychiatrist or psychologist who has experience in assessing capacity. For more information, see How do I assess a person's capacity?
  • If considering using the Mental Health Act, always seek help from the local community mental health team (CMHT) or crisis team, social services, and the on-call psychiatrist. Section 136 may be used by police to take people who appear to be suffering from a mental disorder and are in 'immediate need of care or control' from a public place to a place of safety and enable examination by a registered medical practitioner and interview by an Approved Mental Health Professional (AMHP). See The Mental Health Act (1983) for further information. 
• In emergency situations, consider the person's capacity, but be aware that the steps reasonable when assessing capacity will be different to the steps in non-urgent cases. In such situations, it may be that capacity is only considered briefly. It will almost always be in the person's best interests to give urgent treatment without delay. See How do I assess a person's capacity? for further information.
• If the person is judged to have capacity, and does not have signs of a mental disorder, and is at a low risk of suicide, but is at risk from the effects of their overdose, by law they have the right to refuse hospital admission and/or to refuse lifesaving treatment. In these circumstances: 
  • Take all steps to persuade them to attend hospital or have treatment. If the person allows, involve family and carers.
  • Seek advice from the NPIS, Emergency or Medical consultant, consultant psychiatrist or medical indemnity organisation.
  • Follow the person up and reassess the clinical situation as soon as is clinically appropriate; provide information about the potential consequences of not receiving hospital treatment and assessment; and reassess capacity.
  • Clearly document their wishes and that these are against medical advice.

How is poisoning managed in secondary care?

Medical management

• A further assessment will be carried out, which may include:
  • Administration of antidotes, such as acetylcysteine, naloxone, and flumazenil, if appropriate. 
  • Blood and urine tests, such as toxicological investigations, full blood count, clotting, electrolytes, glucose, liver function tests, and arterial blood gases.
  • ECG and imaging investigations.
• Plasma or serum monitoring. Drugs or poisons that require emergency measurement of their plasma or serum concentration in order to guide clinical management include:
  • Carbamazepine.
  • Carboxyhaemoglobin.
  • Digoxin. 
  • Ethanol.
  • Ethylene glycol.
  • Iron. 
  • Lithium. 
  • Methanol. 
  • Methotrexate.
  • Paracetamol. 
  • Salicylate. 
  • Theophylline. 
  • Valproate.
• Treatment will depend on the type of poison taken, and the severity of the episode.
• Most people will simply be observed, to make sure there are no worsening adverse effects, and that complications do not develop.
  • The length of the observation will depend on the clinical circumstances.
• Prevention of absorption: 
  • Activated charcoal can bind to the poison and prevent absorption. The sooner it is given the more effective, but it may still be effective up to 1 hour after ingestion, or longer for modified release preparations or medicines with antimuscarinic properties. An important use is to prevent the absorption of medicines which are toxic in small amounts, such as antidepressants. 
  • In children this is only used if a potentially toxic amount of a drug that adsorbs to charcoal has been taken, the child has presented within 1 hour of ingestion, in the absence of contraindications, and after a risk-benefit analysis when this is being considered.
• Active elimination is suitable for a limited number of drugs:
  • Repeated doses of activated charcoal enhance the elimination of some drugs even after they have been absorbed, such as carbamazepine, phenobarbital, quinine, theophylline, and dapsone. 
  • Alkalinisation of the urine for salicylate poisoning. 
  • Haemodialysis for ethylene glycol, lithium, methanol, phenobarbital, salicylates, and sodium valproate.
• Removal from the gastrointestinal tract:
  • Gastric lavage is rarely required — it is indicated only if a life-threatening amount has been ingested within the previous hour, and the poison cannot be removed using other methods. It may be useful for drugs such as lithium and iron that are not absorbed by charcoal. Lavage should never be done if a petroleum distillate or a corrosive substance has been ingested.
  • Whole bowel irrigation may be used if there has been poisoning with certain sustained-release or enteric-coated medicines, or in severe poisoning with iron or lithium salts. This should only be performed following discussion with the NPIS.
• Antidotes (if available) may be given for certain poisons, which either prevent the poison from working or reverse the effects of the poison.
  • Acetylcysteine — paracetamol. 
  • Digoxin-specific antibody fragments — digoxin. 
  • Flumazenil injection — benzodiazepines. This reverses the central nervous system and respiratory depression. However, if the person has also taken a tricyclic antidepressant or has epilepsy, there must be caution, as flumazenil can cause seizures and arrhythmias. 
  • Glucagon injection — insulin, beta-blockers, calcium-channel blockers. 
  • Naloxone injection — morphine, heroin, opiates. In people with reduced consciousness due to suspected opioid poisoning, administration which leads to significant improvement in the person's condition within 1-2 minutes is highly suggestive of opioid poisoning.  
  • Desferrioxamine mesilate — iron salts. 
  • Fomepizole — ethylene glycol or methanol. 

Psychiatric assessment and management of deliberate self-poisoning

• People who have deliberately self-poisoned should have a psychosocial assessment of their needs and risks by a specialist mental health professional while they are in hospital. The person's subsequent management is based on this assessment. This is likely to include:
  • Events that preceded the episode of self-harm. 
  • Reasons for self-poisoning. 
  • Assessment of possible suicidal intent. 
  • Current personal difficulties and life issues. 
  • Problems with alcohol or substance misuse. 
  • Whether they have a psychiatric disorder. 
  • Personal risk factors (for example, low socioeconomic status, employment status). 
  • Psychiatric history and history of self-harm. 
  • Risk of further self-harm and suicide. 
  • The person's social supports and coping resources. 
  • Whether the person is willing to accept help, and the help that would most benefit the person.
• People who have a serious psychiatric disorder and/or are at a high risk of suicide are generally admitted for the treatment of the psychiatric disorder. 
• Children and young people aged under 16 who have deliberately self-poisoned should be admitted overnight on a paediatric ward, and be assessed the next day by an appropriately experienced healthcare professional. Young people aged 16 and 17 do not always need to be admitted overnight.