What the label lists and what reports show
Propylthiouracil side effects
Propylthiouracil's FDA label lists its adverse reactions in its own words. FAERS holds 2,050 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is nausea (87 reports).
- Generic listed
- Boxed warning
Check it at the source: the propylthiouracil FDA label on DailyMed (effective August 27, 2026, American Health Packaging); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of Propylthiouracil?Propylthiouracil may cause serious side effects, including: See “What is the most important information I should know about Propylthiouracil?” Low white blood cell counts. This usually happens within the first 3 months of treatment and can be life-threatening. You may have a higher chance of getting an infection when your white blood cell count is low. Call your doctor right away if you have symptoms of infection or illness such as fever, chills, or sore throat. Swelling (inflammation) of the small blood vessels of the body (vasculitis). Some people have developed vasculitis, a serious complication, during their treatment with Propylthiouracil that can lead to death. Vasculitis can involve the small blood vessels of the skin, kidneys, or lungs. Symptoms may vary depending on which blood vessels are affected. […]
Source: FDA drug label, American Health Packaging, effective August 27, 2026 (SPL set d819e532-09ac-434a-84a6-636c4204c7aa), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe following adverse reactions have been reported with the use of propylthiouracil. Because these events generally come from voluntary reporting from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Severe adverse reactions include liver injury presenting as hepatitis, liver failure necessitating liver transplantation or resulting in death (see WARNINGS ). Inhibition of myelopoiesis (agranulocytosis, granulopenia, aplastic anemia, and thrombocytopenia), drug fever, a lupus-like syndrome (including splenomegaly and vasculitis), periarteritis, hypoprothrombinemia, and bleeding have been reported. Nephritis, glomerulonephritis, interstitial pneumonitis, exfoliative dermatitis, and erythema nodosum have also been reported. …
Source: FDA drug label, American Health Packaging, effective August 27, 2026 (SPL set d819e532-09ac-434a-84a6-636c4204c7aa), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,050 reports list propylthiouracil among the medicines taken, each a report of something that happened, not proof the medicine caused it; 180 are coded as a death and 938 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 17 reactions below, 6 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Propylthiouracil: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions