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Fomepizole Side Effects

In Summary

Commonly reported side effects of fomepizole include: headache and nausea. Other side effects include: dizziness. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to fomepizole: parenteral injection concentrate for iv infusion

Side effects include:

Headache, nausea, dizziness, increased drowsiness, bad/metallic taste.

For Healthcare Professionals

Applies to fomepizole: intravenous solution


The most common adverse events were headache, nausea, dizziness, increased drowsiness, and bad taste/metallic taste.[Ref]


Very common (10% or more): Nausea (11%)
Common (1% to 10%): Abdominal pain, vomiting, diarrhea, dyspepsia, heartburn[Ref]

Nervous system

Very common (10% or more): Headache (14%)
Common (1% to 10%): Dizziness, increased drowsiness, bad taste/metallic taste, lightheadedness, seizure, agitation, feeling drunk, vertigo, nystagmus, anxiety, "felt strange", decreased environmental awareness, abnormal smell, roar in ear[Ref]


Common (1% to 10%): Fever, multiorgan system failure, hangover, speech/visual disturbances[Ref]


Common (1% to 10%): Sinus bradycardia/bradycardia, phlebosclerosis, tachycardia, phlebitis, shock, hypotension[Ref]


Common (1% to 10%): Eosinophilia/hypereosinophilia, lymphangitis, disseminated intravascular coagulation, anemia[Ref]


Common (1% to 10%): Transient transaminitis[Ref]


Common (1% to 10%): Pain during injection, inflammation at injection site, application site reaction[Ref]


Common (1% to 10%): Anuria[Ref]


Common (1% to 10%): Hiccups, pharyngitis[Ref]


Common (1% to 10%): Transient blurred vision[Ref]


Common (1% to 10%): Facial flush, rash[Ref]


Common (1% to 10%): Lumbalgia/backache[Ref]


Common (1% to 10%): Decreased appetite


1. "Product Information. Antizol (fomepizole)." Jazz Pharmaceuticals, Palo Alto, CA.

Some side effects of fomepizole may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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