Propylthiouracil
Propylthiouracil (PTU) is an antithyroid medication used to treat hyperthyroidism by reducing the production of thyroid hormones. It is primarily prescribed for conditions such as Graves' disease, toxic multinodular goiter, and in preparation for thyroid surgery. Due to its potential for serious liver toxicity, it is typically reserved for specific situations including first-trimester pregnancy, thyroid storm, or when patients cannot tolerate other antithyroid medications.
Propylthiouracil is an antithyroid drug used to treat overactive thyroid conditions by blocking thyroid hormone production.
This medication carries a boxed (black box) warning — the strongest type of FDA warning. Review the full prescribing information before use.
Key facts at a glance
- ATC
- H03BA02
- RxNorm
- 8794
- Generic
- Propylthiouracil
- Class
- atc-h03
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet
- 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.
Treatment of hyperthyroidism including Graves' disease, toxic multinodular goiter, and pre-operative preparation for thyroidectomy. Also used in the management of thyroid storm.
Propylthiouracil inhibits thyroid peroxidase, the enzyme responsible for iodination of tyrosine residues on thyroglobulin and coupling of iodotyrosines to form T3 and T4. It also inhibits peripheral conversion of T4 to T3.
Requires regular liver function monitoring due to risk of hepatotoxicity. Can cause agranulocytosis—patients should report fever or sore throat immediately. Generally reserved for first trimester pregnancy (not methimazole), thyroid storm, or methimazole intolerance. Must not be used in the third trimester due to liver injury risk.
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 25, 2026. · Read our editorial policy