What is Methimazole: Uses, Warnings & Interactions

What is Methimazole: Uses, Warnings & Interactions

Updated May 14, 2025 • Published Dec 30, 2020

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Methimazole overview

BRAND NAMES:

Tapazole

Generic Names:

Methimazole

Uses:

Treats hyperthyroidism (too much thyroid hormone produced by the thyroid gland).

Therapeutic Classes:

Antithyroid Agent

Forms:

Tablet

How it’s taken:

By mouth

What is Methimazole used for?

What form(s) does Methimazole come in

Tablet

What are common Methimazole doses?

Tablet 5MG
Tablet 10MG
Bottle 5GM of
Bottle 25GM of
Bottle 100GM of

Common Methimazole prescriptions

methIMAzole
10mg tablet
methIMAzole
5mg tablet

How to take Methimazole

Your doctor will tell you how much medicine to use. Do not use more than directed.
Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
Your doctor will tell you how much medicine to use. Do not use more than directed.
Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

What to do if you miss a dose of Methimazole

If you miss a dose or forget to take your medicine, take it as soon as you can. If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose.
Do not use extra medicine to make up for a missed dose.

Methimazole contraindications

This medicine is not right for everyone. Do not use it if you had an allergic reaction to methimazole.

Methimazole warnings

Using this medicine during the first three months of pregnancy can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away.
Tell your doctor if you are breastfeeding, or if you have kidney disease, liver disease, lung disease, or breathing problems.
This medicine may cause the following problems:Liver problemsHypothyroidism (low levels of thyroid in the blood)Vasculitis (swelling of the blood vessels)
Make sure any doctor or dentist who treats you knows that you are using this medicine.
This medicine may make you bleed, bruise, or get infections more easily. Take precautions to prevent illness and injury. Wash your hands often.
Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
Keep all medicine out of the reach of children. Never share your medicine with anyone.
Yellow skin or eyes

Methimazole interactions

Some medicines can affect how methimazole works. Tell your doctor if you are using any of the following:Digitalis, theophyllineBeta blockersBlood thinner (including warfarin)
Make sure any doctor or dentist who treats you knows that you are using this medicine.

Methimazole side effects

Serious Side Effects

Dark or bloody urine, pale stools, loss of appetite, stomach pain, yellow skin or eyes
Fever, chills, cough, sore throat, body aches
Numbness, tingling, or burning in your hands or feet
Chest pain or tightness, troubled breathing, coughing up blood
Unusual bruising, bleeding, or weakness
Unusual weakness or tiredness
Severe skin rash, redness, or itching
Yellow skin or eyes

Less Serious Side Effects

Mild skin rash
Dizziness
Joint pain
Mild nausea, vomiting, stomach upset