Propylthiouracil
Brand: (no brand; generic only)
Boxed warning · ISMP high-alert drug
Severe liver injury and acute liver failure, sometimes fatal; reserve for patients who cannot tolerate methimazole or for the first trimester of pregnancy.
- Caution
- Agranulocytosis: report fever or sore throat at once.
- Pregnancy
- Preferred antithyroid drug in the first trimester only; switch to methimazole afterward because of liver risk.
Common side effects
- Rash
- Joint pain
- Low white cell count
- Liver injury
Key interactions
- Reduces the required warfarin dose as thyroid function normalizes
Counseling points
- Report fever, sore throat, or yellowing of the skin or eyes
- Preferred over methimazole in the first trimester
- Thyroid and liver function are monitored
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High-yield study aid for exam prep, not a substitute for the package insert or a pharmacist’s dispensing reference.