What is Fomepizole? Uses, warnings & side effects

Updated May 14, 2025  •  Published Sep 24, 2021

Fomepizole overview

BRAND NAMES:

Generic Names:

  • Fomepizole

Uses:

  • Treats accidental poisoning caused by ethylene glycol (anti-freeze) or methanol.

Therapeutic Classes:

  • Antidote

Forms:

  • Injectable

How it’s taken:

  • By injection

What is Fomepizole used for?

What form(s) does Fomepizole come in?

  • Injectable

What are common Fomepizole dosages?

  • Vial 1.5ML of 1.5GM/1.5ML

Fomepizole images - What does Fomepizole look like?

  • Fomepizole
    1.5ml of 1.5gm/1.5ml vial

How to take Fomepizole

  • Injection routeYour doctor will prescribe your dose and schedule. This medicine is given through a needle placed in a vein.

  • Injection routeA nurse or other health provider will give you this medicine.

What to do if you miss a dose of Fomepizole

Fomepizole contraindications - Who shouldn't take Fomepizole?

  • You should not receive this medicine if you have had an allergic reaction to fomepizole.

Fomepizole warnings

  • Make sure your doctor knows if you are pregnant or breast feeding.

  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.

  • This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.

  • Fever, sore throat.

  • Lightheadedness or fainting.

  • Pain, redness, itching, swelling, blistering, or rash where the needle is placed.

  • Speech problems, or inability to stand or walk.

  • Seizure.

  • Severe nausea, vomiting, or diarrhea.

  • Unusual bleeding, bruising, or weakness.

Fomepizole interactions & what to avoid when taking Fomepizole

  • Make sure your doctor knows if you are using medicine for seizure such as phenytoin (Dilantin®) or carbamazepine (Tegretol®). Tell your doctor if you use stomach medicine such as cimetidine (Tagamet®), or medicine for fungal infection such as ketoconazole (Nizoral®).

  • Do not drink alcohol while you are using this medicine.

  • This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.

Fomepizole side effects - How does Fomepizole make you feel?

Serious Side Effects

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

  • Decrease in how much or how often you urinate.

  • Fast or slow heartbeat.

  • Fever, sore throat.

  • Lightheadedness or fainting.

  • Pain, redness, itching, swelling, blistering, or rash where the needle is placed.

  • Speech problems, or inability to stand or walk.

  • Seizure.

  • Severe nausea, vomiting, or diarrhea.

  • Unusual bleeding, bruising, or weakness.

Less Serious Side Effects

  • Blurred vision, headache, or ringing in your ears.

  • Mild nausea, vomiting, diarrhea, loss of appetite, hiccups, or bad or metallic taste in your mouth.

  • Mild skin rash or itching.

  • Trouble sleeping.

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