Methimazole
Methimazole is an antithyroid medication used to treat hyperthyroidism, including conditions like Graves' disease and toxic multinodular goiter. It works by inhibiting an enzyme required for thyroid hormone production, helping to reduce excessive thyroid hormone levels in the body.
Methimazole is an antithyroid drug that reduces thyroid hormone production to treat conditions like Graves' disease and hyperthyroidism.
Key facts at a glance
- ATC
- H03BB02
- RxNorm
- 6835
- Generic
- Methimazole
- Class
- atc-h03
- Brands
- Felanorm, Reguzol, Felimazole
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet, solution
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Methimazole treats hyperthyroidism, including Graves' disease, toxic multinodular goiter, and preparation for thyroid surgery or radioactive iodine therapy. It is also used for symptomatic control of hyperthyroidism when other treatments are not appropriate.
Methimazole inhibits thyroid peroxidase, an enzyme essential for the synthesis of thyroid hormones T3 and T4. By blocking this process, it reduces the production of excess thyroid hormones, helping restore normal thyroid function.
Methimazole requires regular blood monitoring for thyroid function and liver enzymes. Rare but serious side effects include agranulocytosis and hepatotoxicity. It is contraindicated in patients with hypersensitivity to the drug and should not be used during breastfeeding. Common side effects may include skin rash, joint pain, and gastrointestinal upset.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy