Pharmacology · Medicines for alcohol use disorder
Disulfiram !
A medicine that makes drinking alcohol very unpleasant by blocking acetaldehyde breakdown. It is never given without the person's full knowledge.
Updated 2026-11-01
Mechanism of action
Ethanol is turned into acetaldehyde and then into acetate by aldehyde dehydrogenase. Disulfiram, through its active metabolites, irreversibly inactivates this enzyme, so even a little alcohol makes acetaldehyde build up in the blood and causes a sudden, unpleasant and sometimes dangerous reaction.
- Ethanol is oxidised to acetaldehyde
- Disulfiram metabolites block aldehyde dehydrogenase
- Acetaldehyde builds up in the blood
- Flushing, headache, vomiting and low blood pressure
Pharmacokinetics
- Metabolism
- Converted to active metabolites that inactivate the enzyme
- Half-life
- The enzyme block lasts: a reaction is possible up to 14 days after the last dose
- Onset and duration
- Started only after at least 12 hours without alcohol
Indications
- Aid in selected people with chronic alcohol use disorder who want to stay sober, with supportive and psychological treatment Alcohol use disorder →
Adverse effects
Common
- Mild drowsiness and tiredness in the first weeks
- Metallic or garlic-like aftertaste
- Headache, impotence and skin eruptions
Contraindications
- Alcohol intoxication, or giving it without the person's full knowledge
- Recent or current metronidazole, paraldehyde, alcohol or alcohol-containing products (such as cough syrups)
- Severe heart muscle disease or coronary occlusion
- Psychoses
- Hypersensitivity to disulfiram or thiuram compounds (rubber)
Key interactions
- Alcohol in any form (sauces, vinegars, cough mixtures, aftershave, rubbing lotions)
- Disulfiram–alcohol reaction
- Metronidazole
- Contraindicated
- Phenytoin
- Phenytoin toxicity; levels are checked
- Oral anticoagulants
- Longer prothrombin time; the dose may need adjustment
- Isoniazid
- Unsteady gait or mental changes
What is monitored
- Liver tests at baseline and about 10 to 14 days later, then periodically
- Blood counts and chemistry
- Phenytoin levels or prothrombin time if those drugs are used
Administration and safety
- Given by mouth, only with the person's full knowledge and consent
- Never started in someone intoxicated; at least 12 hours alcohol-free first
- Relatives are told it must never be given secretly
Nursing care
- Confirm at least 12 hours without alcohol before the first dose
- Teach to avoid hidden alcohol: sauces, vinegars, cough syrups, aftershave, rubbing lotions
- Teach that a reaction is possible up to 14 days after the last dose
- Teach to report yellow skin, dark urine or tiredness (hepatitis)
- Suggest carrying a card that states disulfiram use, the reaction symptoms and whom to call
Pregnancy and breastfeeding
Safety in pregnancy is not established; it is used only when the likely benefit outweighs the possible risk.
Test yourself
Think of the answer, then tap the question to see it.
Why does alcohol cause flushing and vomiting in someone on disulfiram?
Aldehyde dehydrogenase is blocked, so acetaldehyde builds up in the blood.
For how long after the last dose can a disulfiram–alcohol reaction occur?
Up to 14 days.
Which antibiotic is contraindicated with disulfiram?
Metronidazole.
Which organ is monitored with blood tests during disulfiram treatment?
The liver, because of the risk of hepatitis and liver failure.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - DISULFIRAM tablet (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 27 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.