Methimazole: uses, side effects & brands

Written & medically reviewed by Dr. Sanjay Anbu, MBBS · Last reviewed 5 November 2026

Methimazole treats hyperthyroidism (carbimazole converts to it in the body). It belongs to the Thyroid & hormone medicine group. These treat an overactive thyroid and some hormone-related conditions.

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Drug type — dosing is set by your doctor

Measure	Range
Drug class	Thyroid & hormone medicine
Type	Prescription
Dose	Individual — ask your doctor or pharmacist

What it is used for

Overactive thyroid (Graves' disease)
Overactive thyroid nodules (toxic nodular goitre)
Calming the thyroid before surgery or radioiodine

Common brand names

India: Thyrozole, Methmr
Worldwide: Tapazole

Common side effects

Nausea or mild stomach upset
Itchy rash
Joint aches
Altered taste or hair thinning

Before taking it — precautions

Pregnancy — methimazole is usually avoided in the first three months; plan pregnancy with your doctor
Tell your doctor about liver disease or if you are breastfeeding
Regular blood tests are needed to adjust treatment

When to see a doctor urgently

Sore throat, mouth ulcers, fever or other signs of infection — stop and get a blood test the same day (urgent)
Yellow skin or eyes, dark urine or pale stools (urgent)
Severe rash, itching or swelling of the face

Not a prescription — no dose shown. The right dose of methimazole depends on age, weight, kidney/liver function and the condition, so MedDroid does not show a dose here. Always get your dose from a doctor or pharmacist and the leaflet inside the pack. General educational information only.

Frequently asked questions

Is methimazole the same as carbimazole?

Carbimazole turns into methimazole in the body, so they work the same way. Doses are not interchangeable, so do not swap without your doctor.

Why must I report a sore throat?

Rarely, methimazole lowers infection-fighting white cells. A blood test tells whether you need to stop.

Can I take it in pregnancy?

In early pregnancy doctors usually prefer PTU instead, then may switch back to methimazole later. Do not change on your own.

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Sources & further reading

Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.