Fomepizole at a glance
Medicine class
Antidote and competitive alcohol dehydrogenase inhibitor
Licensed use
Confirmed or suspected ethylene glycol poisoning
Administration
Diluted and given by slow intravenous infusion in hospital; never undiluted or as a bolus
Key interaction
Ethanol can slow elimination of both substances and is generally not recommended
What is Fomepizole used for?
The selected UK product has one licensed indication. Methanol poisoning is a specialist, non-licensed use.
Licensed: confirmed or suspected ethylene glycol ingestion.
Non-licensed: specialist treatment of methanol poisoning to limit toxic formate formation.
How does Fomepizole work?
Fomepizole competitively blocks alcohol dehydrogenase, limiting formation of acidic, kidney-damaging ethylene glycol metabolites. The same blockade can reduce toxic metabolite formation after methanol exposure.
Fomepizole preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 1 g/mL
How to take Fomepizole
Fomepizole is administered by trained healthcare professionals in hospital.
The concentrate must be diluted before intravenous infusion.
It must not be given undiluted or by bolus injection.
Food does not affect intravenous administration.
The solution may solidify at cooler temperatures; correct warming can return it to liquid without affecting its stated quality.
Fomepizole side effects
Common or expected effects
- Dizziness or headache
- Nausea, vomiting, diarrhoea, indigestion or hiccups
- Anxiety or agitation
- Rash or itching
- Infusion-site inflammation or reaction
- Changes in heart rate, blood pressure, liver enzymes or blood counts
Get urgent medical advice
- Facial or throat swelling, bronchospasm, severe breathing difficulty or collapse
- Seizure, marked visual disturbance or severe neurological change
Fomepizole in pregnancy
Human pregnancy data are unavailable, and animal evidence indicates potential reproductive harm. Use is advised only when clearly necessary, following urgent specialist assessment.
Fomepizole while breastfeeding
It is unknown whether fomepizole enters human milk. Breastfeeding should be temporarily stopped during treatment, with individual advice about expressing milk and restarting.
Fomepizole interactions
Interaction evidence is limited.
Ethanol or alcohol-containing treatment
Concurrent use slows elimination of both ethanol and fomepizole, so it is generally not recommended.
Medicines metabolised by cytochrome P450 enzymes
Preclinical findings suggest possible enzyme inhibition or induction, but clinical risk in humans cannot currently be predicted.
Common questions about Fomepizole
Answers are fully visible for fast scanning and source review.
What poisoning does Fomepizole treat?
The selected UK product is licensed for confirmed or suspected ethylene glycol poisoning, commonly associated with antifreeze ingestion.
Is it used for methanol poisoning?
Yes, specialists use it to block methanol metabolism, but this is not a licensed indication of the selected UK product.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.