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What the label lists and what reports show

Fomepizole side effects

Fomepizole's FDA label lists its adverse reactions in its own words. FAERS holds 189 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is toxicity to various agents (50 reports).

  • Generic listed

Check it at the source: the fomepizole FDA label on DailyMed (effective December 19, 2024); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

The most frequent adverse events reported as drug-related or unknown relationship to study drug in the 78 patients and 63 normal volunteers who received fomepizole injection were headache ( 14% ), nausea (11%), and dizziness, increased drowsiness, and bad taste / metallic taste (6% each). All other adverse events in this population were reported in approximately 3% or fewer of those receiving fomepizole and were as follows: Body as a Whole: Abdominal pain, fever, multiorgan system failure, pain during fomepizole injection, inflammation at injection site, lumbalgia/backache, hangover. Cardiovascular: Sinus bradycardia/bradycardia, phlebosclerosis, tachycardia, phlebitis, shock, hypotension. Gastrointestinal: Vomiting, diarrhea, dyspepsia, heartburn, decreased appetite, transient transaminitis. …

Source: FDA drug label, Navinta LLC, effective December 19, 2024 (SPL set 6fed6052-f159-46d6-8be1-31e18a7ba918), via openFDA; the full label on DailyMed

What do FAERS reports show?

189 reports list fomepizole among the medicines taken, each a report of something that happened, not proof the medicine caused it; 69 are coded as a death and 137 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 3 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.

The 25 most reported reactions

  • Drug Ineffective (a use or a product term, not a reaction)69
  • Toxicity To Various Agents50
  • Overdose (a use or a product term, not a reaction)37
  • Off Label Use (a use or a product term, not a reaction)33
  • Metabolic Acidosis23
  • Hypotension (named in the label)18
  • Intentional Overdose (a use or a product term, not a reaction)18
  • Hepatotoxicity17
  • Acute Kidney Injury16
  • Brain Oedema16
  • Drug Ineffective For Unapproved Indication (a use or a product term, not a reaction)16
  • Drug-Induced Liver Injury13
  • Encephalopathy12
  • Hypoglycaemia11
  • Lactic Acidosis11
  • Acute Hepatic Failure10
  • Coagulopathy10
  • Tachycardia (named in the label)9
  • Coma8
  • Liver Injury8
  • Acidosis (named in the label)7
  • Brain Herniation7
  • Mental Status Changes7
  • Product Use In Unapproved Indication (a use or a product term, not a reaction)7
  • Alcohol Poisoning6

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Fomepizole: the full record
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Side effects hub
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