Propylthiouracil adverse effects

Adverse effects occur in 3-12% in the form of rash, fever, urticaria, vasculitis, arthralgia, a lupuslike reaction, cholestatic jaundice, hepatitis, lym-phadenopathy and polyserositis but the most dangerous adverse effect is agranulocytosis (it occurs only in 0.3-0.6%). The reaction is readily reversible when the drug is discontinued. Cross-sensitivity between propylthiouracil and methimazole is about 50%, therefore switching drugs in patients with severe reactions is not recommended. 

Adverse reactions to the thioamides occur in 3-12% of treated patients. Most reactions occur early, especially nausea and gastrointestinal distress. An altered sense of taste or smell may occur with methimazole. The most common adverse effect is a maculopapular pruritic rash (4-6%), at times accompanied by systemic signs such as fever. Rare adverse effects include an urticarial rash, vasculitis, a lupus-like reaction, lymphadenopathy, hypoprothrombinemia, exfoliative dermatitis, polyserositis, and acute arthralgia. Hepatitis (more common with propylthiouracil) and cholestatic jaundice (more common with methimazole) can be fatal, although asymptomatic elevations in transaminase levels also occur. 

Acute overdose of 13 g of propylthiouracil had no serious adverse effects, except for a temporary reduction in serum triiodothyronine (SEDA-5, 382). 

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