Reviewed on 6/21/2022

What Is Fomepizole and How Does It Work?

Fomepizole is a prescription medication used to reverse methanol and ethylene glycol poisoning.

  • Fomepizole is available under the following different brand names: Antizol

What Are Side Effects Associated with Using Fomepizole?

Common side effects of Fomepizole include:

  • mild skin rash,
  • heartburn,
  • nausea,
  • vomiting,
  • diarrhea,
  • loss of appetite,
  • dizziness,
  • drowsiness, anxiety,
  • headache,
  • metallic taste in the mouth,
  • hangover feeling,
  • back pain,
  • sore throat,
  • ringing in ears, or
  • changes in vision,
  • changes in smell or taste senses.

Serious side effects of Fomepizole include:

  • skin rash, bruising, severe tingling, numbness, pain, and muscle weakness.
  • severe nausea, severe dizziness, or spinning sensation; or
  • a light-headed feeling.

Rare side effects of Fomepizole include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088


Digestive Disorders: Common Misconceptions See Slideshow

What Are Dosages of Fomepizole?

 Adult and pediatric dosage

Injectable solution

  • 1.5 g/1.5 mL
  • Methanol & Ethylene Glycol Poisoning
  • Adult dosage
  • Load 15 mg/kg IV infusion over 30 min, THEN  
  • 10 mg/kg IV every 12 hours for 4 doses, THEN increase to 15 mg/kg every 12 hours
  • Maintain serum level of 8.6-24.6 mg/L

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Fomepizole?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Fomepizole has no noted severe interactions with any other drugs.
  • Fomepizole has no noted serious interactions with any other drugs.
  • Fomepizole has no noted moderate interactions with any other drugs.
  • Fomepizole has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Fomepizole?


  • Hypersensitivity reaction to the drug or other pyrazoles

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Fomepizole?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Fomepizole?”


  • Not to be given undiluted or by bolus injection; venous irritation and phlebosclerosis were noted in two of six normal volunteers given bolus injections (over 5 minutes) of 25 mg/mL
  • Do not use polycarbonate syringes or polycarbonate-containing needles (including polycarbonate filter needles) when diluting or administering the drug; the drug can interact with polycarbonate, compromising the integrity of the syringe and/or needle component containing polycarbonate
  • Minor allergic reactions (mild rash, eosinophilia) have been reported in a few patients receiving therapy

Pregnancy & Lactation

  • Use with caution if benefits outweigh risks during pregnancy


  • Excretion in milk unknown; use with caution


About how much does an adult human brain weigh? See Answer

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