Propylthiouracil side effects: what 2,050 FDA adverse event reports show
Drug class
Thyroid Hormone Synthesis Inhibitor
Who reports
2,050 reports · 86% serious · 180 with death outcome · 74% female
Used for
Propylthiouracil tablets are indicated: in patients with Graves’ disease with hyperthyroidism or toxic multinodular goiter who are intolerant of methimazole and for whom surgery or radioactive iodine therapy is not an appropriate treatment option to ameliorate symptoms of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy in patients who are intolerant of methimazole
What it is
DESCRIPTION Propylthiouracil, USP is one of the thiocarbamide compounds. It is a white, powdery, crystalline substance that has a bitter taste and is very slightly soluble in water. Propylthiouracil is an antithyroid drug administered orally.
Boxed warning
Severe liver injury and acute liver failure, in some cases fatal, have been reported in patients treated with propylthiouracil. These reports of hepatic reactions include cases requiring liver transplantation in adult and pediatric patients.
Causality screen of the 40 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 26 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Hyperthyroidism | 138 | 98.5 83.8–115.8ROR 105.5 · χ² 13,104 / p <1e-300 | 96.3 EB05 83.6 · IC025 +5.9 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 65.2 · ♀ 52% (drug 74%) · 92% clinician | no trial data cached |
| Cardiogenic shock | 50 | 36.0 27.3–47.3ROR 36.8 · χ² 1,660 / p <1e-300 | 35.4 EB05 27.9 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious PRR 23.8 · 100% clinician | no trial data cached |
| Acute hepatic failure | 46 | 34.7 26.1–46.2ROR 35.5 · χ² 1,468 / p <1e-300 | 34.2 EB05 26.6 · IC025 +4.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 23.0 · 98% clinician | no trial data cached |
| Agranulocytosis (severe loss of white cells) | 60 | 33.3 25.9–42.8ROR 34.3 · χ² 1,843 / p <1e-300 | 32.9 EB05 26.5 · IC025 +4.3 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 22.1 · 96% clinician | no trial data cached |
| Vasculitis | 32 | 28.1 20.0–39.7ROR 28.6 · χ² 809 / p 3e-178 | 27.7 EB05 20.5 · IC025 +3.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 20.1 | no trial data cached |
| Sinus bradycardia | 16 | 16.9 10.4–27.6ROR 17.0 · χ² 224 / p 7e-51 | 16.2 EB05 10.1 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 11.6 | no trial data cached |
| Premature baby | 49 | 16.6 12.6–21.9ROR 17.0 · χ² 704 / p 2e-155 | 16.5 EB05 12.9 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious PRR 11.0 · 100% clinician | no trial data cached |
| Hepatic encephalopathy | 15 | 16.5 9.9–27.2ROR 16.6 · χ² 202 / p 3e-46 | 15.7 EB05 9.5 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 11.0 | no trial data cached |
| Hepatotoxicity (liver damage) | 35 | 16.2 11.6–22.5ROR 16.4 · χ² 483 / p 2e-107 | 15.9 EB05 11.9 · IC025 +3.2 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 10.0 · 97% clinician | no trial data cached |
| Premature delivery | 25 | 16.0 10.8–23.6ROR 16.2 · χ² 337 / p 2e-75 | 15.6 EB05 10.9 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 10.9 · ♀ 100% (drug 74%) · 96% clinician | no trial data cached |
| Hypothyroidism | 47 | 15.1 11.4–20.1ROR 15.4 · χ² 606 / p 5e-134 | 14.9 EB05 11.6 · IC025 +3.2 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 10.6 · 93% clinician | no trial data cached |
| Foetal exposure during pregnancy | 117 | 14.8 12.4–17.6ROR 15.6 · χ² 1,490 / p <1e-300 | 14.7 EB05 12.6 · IC025 +3.5 3/3 methods agree | Reporting / coding artifact | serious PRR 10.0 · 96% clinician | no trial data cached |
| Circulatory collapse | 24 | 14.4 9.7–21.4ROR 14.5 · χ² 285 / p 3e-64 | 13.9 EB05 9.5 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 9.6 · ♀ 52% (drug 74%) | no trial data cached |
| Exposure during pregnancy | 85 | 14.0 11.4–17.2ROR 14.6 · χ² 1,015 / p 6e-223 | 13.9 EB05 11.5 · IC025 +3.3 3/3 methods agree | Reporting / coding artifact | serious PRR 11.9 · ♀ 100% (drug 74%) · 93% clinician | no trial data cached |
| Drug-induced liver injury | 38 | 12.6 9.2–17.3ROR 12.8 · χ² 395 / p 3e-88 | 12.3 EB05 9.1 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 · 100% clinician | no trial data cached |
| Caesarean section | 14 | 12.2 7.2–20.5ROR 12.3 · χ² 133 / p 5e-31 | 10.8 EB05 6.2 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Multiple organ dysfunction syndrome | 33 | 12.1 8.6–17.0ROR 12.3 · χ² 325 / p 5e-73 | 11.6 EB05 8.4 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.0 · 100% clinician | no trial data cached |
| Hyperbilirubinaemia | 11 | 10.9 6.1–19.7ROR 11.0 · χ² 90 / p 2e-21 | 9.0 EB05 4.9 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 | no trial data cached |
| Renal tubular necrosis | 10 | 10.4 5.6–19.3ROR 10.5 · χ² 76 / p 2e-18 | 8.3 EB05 4.4 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 7.0 | no trial data cached |
| Drug reaction with eosinophilia and systemic symptoms | 25 | 10.0 6.8–14.8ROR 10.1 · χ² 194 / p 2e-44 | 9.2 EB05 6.3 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.7 · ♀ 95% (drug 74%) · 100% clinician | no trial data cached |
| Cardiomegaly | 12 | 9.9 5.6–17.4ROR 10.0 · χ² 87 / p 5e-21 | 8.2 EB05 4.6 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Maternal exposure during pregnancy | 76 | 8.8 7.1–11.0ROR 9.1 · χ² 521 / p 1e-115 | 8.5 EB05 7.0 · IC025 +2.7 3/3 methods agree | Reporting / coding artifact | serious PRR 5.9 · ♀ 100% (drug 74%) · 97% clinician | no trial data cached |
| Hepatitis (liver inflammation) | 22 | 8.8 5.8–13.3ROR 8.9 · χ² 144 / p 1e-33 | 7.8 EB05 5.3 · IC025 +2.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.0 · 95% clinician | no trial data cached |
| Cholestasis (bile flow blockage) | 16 | 8.6 5.3–14.0ROR 8.6 · χ² 100 / p 9e-24 | 7.3 EB05 4.6 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 5.8 | no trial data cached |
| Ventricular tachycardia | 13 | 8.0 4.7–13.8ROR 8.1 · χ² 73 / p 6e-18 | 6.6 EB05 4.0 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 5.4 | no trial data cached |
| Hepatic failure | 23 | 7.8 5.2–11.7ROR 7.9 · χ² 129 / p 3e-30 | 6.9 EB05 4.8 · IC025 +2.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.0 · 100% clinician | no trial data cached |
| Eosinophilia | 13 | 7.6 4.4–13.1ROR 7.7 · χ² 68 / p 7e-17 | 6.3 EB05 3.8 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 5.3 | no trial data cached |
| Drug exposure during pregnancy | 25 | 7.4 5.0–11.0ROR 7.5 · χ² 133 / p 6e-31 | 6.7 EB05 4.7 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 4.0 | no trial data cached |
| Rhabdomyolysis (muscle breakdown) | 30 | 7.4 5.2–10.5ROR 7.5 · χ² 159 / p 8e-37 | 6.7 EB05 4.9 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 · ♀ 46% (drug 74%) · 100% clinician | no trial data cached |
| Disseminated intravascular coagulation | 10 | 7.2 3.9–13.5ROR 7.3 · χ² 48 / p 2e-12 | 5.7 EB05 3.2 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 | no trial data cached |
| Sinus tachycardia | 10 | 7.2 3.9–13.4ROR 7.3 · χ² 48 / p 3e-12 | 5.7 EB05 3.2 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 | no trial data cached |
| Cardiac arrest (heart stopping) | 55 | 6.8 5.2–8.8ROR 7.0 · χ² 267 / p 3e-60 | 6.5 EB05 5.1 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 · 96% clinician | no trial data cached |
| Liver injury | 16 | 6.8 4.2–11.0ROR 6.8 · χ² 73 / p 6e-18 | 5.8 EB05 3.7 · IC025 +1.7 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 3.8 | no trial data cached |
| Thyroid disorder | 10 | 6.6 3.6–12.3ROR 6.7 · χ² 42 / p 4e-11 | 5.3 EB05 3.0 · IC025 +1.3 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 6.1 | no trial data cached |
| Jaundice (yellowing of skin/eyes) | 17 | 6.4 4.0–10.4ROR 6.5 · χ² 73 / p 7e-18 | 5.6 EB05 3.7 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.3 | no trial data cached |
| Product physical issue | 12 | 6.2 3.5–10.8ROR 6.2 · χ² 47 / p 4e-12 | 5.1 EB05 3.1 · IC025 +1.4 3/3 methods agree | Reporting / coding artifact | serious n=10 | no trial data cached |
| International normalised ratio increased | 16 | 5.7 3.5–9.3ROR 5.7 · χ² 57 / p 2e-14 | 4.9 EB05 3.2 · IC025 +1.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.2 | no trial data cached |
| Cardio-respiratory arrest | 22 | 5.3 3.5–8.1ROR 5.4 · χ² 74 / p 5e-18 | 4.8 EB05 3.4 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 3.4 | no trial data cached |
| Treatment noncompliance | 27 | 5.1 3.5–7.4ROR 5.1 · χ² 85 / p 2e-20 | 4.7 EB05 3.4 · IC025 +1.6 3/3 methods agree | Reporting / coding artifact | serious PRR 4.7 · 96% clinician | no trial data cached |
| Drug ineffective for unapproved indication | 24 | 4.4 3.0–6.6ROR 4.4 · χ² 60 / p 5e-15 | 4.1 EB05 2.9 · IC025 +1.4 3/3 methods agree | Reporting / coding artifact | serious PRR 6.0 · ♀ 33% (drug 74%) · 91% clinician | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Hyperthyroidism | 138 | 98.5 83.8–115.8ROR 105.5 · χ² 13,104 / p <1e-300 | 96.3 EB05 83.6 · IC025 +5.9 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 65.2 · ♀ 52% (drug 74%) · 92% clinician | no trial data cached |
| Foetal exposure during pregnancy | 117 | 14.8 12.4–17.6ROR 15.6 · χ² 1,490 / p <1e-300 | 14.7 EB05 12.6 · IC025 +3.5 3/3 methods agree | Reporting / coding artifact | serious PRR 10.0 · 96% clinician | no trial data cached |
| Exposure during pregnancy | 85 | 14.0 11.4–17.2ROR 14.6 · χ² 1,015 / p 6e-223 | 13.9 EB05 11.5 · IC025 +3.3 3/3 methods agree | Reporting / coding artifact | serious PRR 11.9 · ♀ 100% (drug 74%) · 93% clinician | no trial data cached |
| Maternal exposure during pregnancy | 76 | 8.8 7.1–11.0ROR 9.1 · χ² 521 / p 1e-115 | 8.5 EB05 7.0 · IC025 +2.7 3/3 methods agree | Reporting / coding artifact | serious PRR 5.9 · ♀ 100% (drug 74%) · 97% clinician | no trial data cached |
| Agranulocytosis (severe loss of white cells) | 60 | 33.3 25.9–42.8ROR 34.3 · χ² 1,843 / p <1e-300 | 32.9 EB05 26.5 · IC025 +4.3 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 22.1 · 96% clinician | no trial data cached |
| Cardiac arrest (heart stopping) | 55 | 6.8 5.2–8.8ROR 7.0 · χ² 267 / p 3e-60 | 6.5 EB05 5.1 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 · 96% clinician | no trial data cached |
| Cardiogenic shock | 50 | 36.0 27.3–47.3ROR 36.8 · χ² 1,660 / p <1e-300 | 35.4 EB05 27.9 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious PRR 23.8 · 100% clinician | no trial data cached |
| Premature baby | 49 | 16.6 12.6–21.9ROR 17.0 · χ² 704 / p 2e-155 | 16.5 EB05 12.9 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious PRR 11.0 · 100% clinician | no trial data cached |
| Hypothyroidism | 47 | 15.1 11.4–20.1ROR 15.4 · χ² 606 / p 5e-134 | 14.9 EB05 11.6 · IC025 +3.2 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 10.6 · 93% clinician | no trial data cached |
| Acute hepatic failure | 46 | 34.7 26.1–46.2ROR 35.5 · χ² 1,468 / p <1e-300 | 34.2 EB05 26.6 · IC025 +4.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 23.0 · 98% clinician | no trial data cached |
| Drug-induced liver injury | 38 | 12.6 9.2–17.3ROR 12.8 · χ² 395 / p 3e-88 | 12.3 EB05 9.1 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 · 100% clinician | no trial data cached |
| Hepatotoxicity (liver damage) | 35 | 16.2 11.6–22.5ROR 16.4 · χ² 483 / p 2e-107 | 15.9 EB05 11.9 · IC025 +3.2 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 10.0 · 97% clinician | no trial data cached |
| Multiple organ dysfunction syndrome | 33 | 12.1 8.6–17.0ROR 12.3 · χ² 325 / p 5e-73 | 11.6 EB05 8.4 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.0 · 100% clinician | no trial data cached |
| Vasculitis | 32 | 28.1 20.0–39.7ROR 28.6 · χ² 809 / p 3e-178 | 27.7 EB05 20.5 · IC025 +3.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 20.1 | no trial data cached |
| Cardiac failure congestive | 30 | 3.8 2.7–5.4ROR 3.8 · χ² 59 / p 8e-15 | 3.6 EB05 2.7 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 2.5 | no trial data cached |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Cardiogenic shock — n=50, PRR 36.0
- Premature baby — n=49, PRR 16.6
- Premature delivery — n=25, PRR 16.0
- Circulatory collapse — n=24, PRR 14.4
- Drug-induced liver injury — n=38, PRR 12.6
- Multiple organ dysfunction syndrome — n=33, PRR 12.1
- Drug reaction with eosinophilia and systemic symptoms — n=25, PRR 10.0
- Rhabdomyolysis — n=30, PRR 7.4
- Cardiac arrest — n=55, PRR 6.8
- Cardio-respiratory arrest — n=22, PRR 5.3
✓ A hand-written Bradford Hill causality assessment exists for this drug: Propylthiouracil ↔ Hepatotoxicity / acute liver failure.
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Propylthiouracil?
In FDA FAERS, the most frequently co-reported reaction terms for Propylthiouracil are hyperthyroidism, agranulocytosis, cardiac arrest, cardiogenic shock, premature baby, hypothyroidism. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Propylthiouracil have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: Severe liver injury and acute liver failure, in some cases fatal, have been reported in patients treated with propylthiouracil. These reports of hepatic reactions include cases requiring liver transplantation in adult and pediatric patients.
Do FAERS signals prove that Propylthiouracil causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 804fa92a-a5ba-4be0-aa44-a40a2e89fde6, effective 20230701; matched on
openfda.generic_name.exact:"PROPYLTHIOURACIL") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 66 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.