propylthiouracil
Brand names: PTU
Propylthiouracil (PTU) is a medicine that treats an overactive thyroid. It helps to lower the amount of thyroid hormone your body makes.
Drug Pricing (NADAC)
Generic Price
$0.29/unit
Generic Available
Yes (4 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
PTU treats hyperthyroidism, which is when your thyroid gland makes too much thyroid hormone.
Common side effects
Skin rash, Hives, Nausea
Key warnings
PTU can cause severe liver problems, including liver failure, which can be fatal.
How It Works
PTU works by stopping your thyroid gland from making too much thyroid hormone. It does this by interfering with the process that creates these hormones. This helps to reduce the symptoms of hyperthyroidism.
How to Take It
Take PTU by mouth. The usual starting dose for adults is 300 mg per day, divided into 3 equal doses taken about 8 hours apart. Your doctor may increase this to 400 mg daily if you have severe hyperthyroidism or a very large goiter. The usual maintenance dose is 100 to 150 mg daily, but follow your doctor's specific instructions.
Pregnancy & Breastfeeding
PTU may be used during the first 3 months of pregnancy if an antithyroid drug is needed. Talk to your doctor about the risks and benefits of taking PTU while pregnant or breastfeeding.
Missed Dose
If you miss a dose of PTU, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store PTU tablets at room temperature, between 59° to 86°F (15° to 30°C).
Side Effects (from patient reports)
Based on 1,034 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 1,982 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
1,982
Death-Related Reports
170
Hospitalization Reports
907
Top Indication
Hyperthyroidism
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DRUG INEFFECTIVE | 189 |
| 2 | OFF LABEL USE | 149 |
| 3 | HYPERTHYROIDISM | 135 |
| 4 | FOETAL EXPOSURE DURING PREGNANCY | 113 |
| 5 | NAUSEA | 87 |
| 6 | EXPOSURE DURING PREGNANCY | 84 |
| 7 | ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY POSITIVE VASCULITIS | 83 |
| 8 | MATERNAL EXPOSURE DURING PREGNANCY | 68 |
| 9 | HYPOTENSION | 67 |
| 10 | AGRANULOCYTOSIS | 59 |
| 11 | FATIGUE | 58 |
| 12 | PYREXIA | 58 |
| 13 | PRODUCT USE IN UNAPPROVED INDICATION | 56 |
| 14 | VOMITING | 56 |
| 15 | CARDIAC ARREST | 54 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
PTU can cause severe liver problems, including liver failure, which can be fatal. You should only use PTU if you cannot take methimazole and surgery or radioactive iodine are not right for you. PTU may be the best choice if you need an antithyroid drug during or just before the first 3 months of pregnancy.
Common Questions
What should I do if I experience nausea after taking PTU?
Can PTU affect my ability to drive or operate machinery?
How long does it take for PTU to start working?
Are there any foods or drinks I should avoid while taking PTU?
What tests will my doctor do while I'm taking PTU?
Can I stop taking PTU once my thyroid levels are normal?
What are the symptoms of liver problems I should watch out for?
Can PTU cause hair loss?
Is it safe to take other medications with PTU?
What should I do if I think I'm having an allergic reaction to PTU?
What are the common side effects of propylthiouracil?
What drug class is propylthiouracil?
Is propylthiouracil safe during pregnancy?
Related Medications in Anti-Thyroid Agent
Other drugs grouped near propylthiouracil — same-class peers and common alternatives.
levothyroxine
Synthroid, Levoxyl
Levothyroxine is a medicine that replaces a hormone normally made by your thyroid gland.
Compare with propylthiouracil →
liothyronine
Cytomel
Liothyronine (Cytomel) is a medicine that replaces a thyroid hormone called T3.
Compare with propylthiouracil →
methimazole
Tapazole
Methimazole (Tapazole) is a medicine that lowers the amount of thyroid hormone your body makes.
Compare with propylthiouracil →
thyroid (desiccated)
Armour Thyroid, Nature-Throid
Armour Thyroid is a natural thyroid hormone medicine.
Compare with propylthiouracil →
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What the FDA Data Shows for propylthiouracil
The FDA label for propylthiouracil (sold under brand names such as PTU) classifies it as a prescription-only medication in the Anti-Thyroid Agent class. PTU treats hyperthyroidism, which is when your thyroid gland makes too much thyroid hormone. Official labeling lists 18 commonly reported side effects, including Skin rash, Hives, Nausea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 1,034 voluntary reports. Interaction data is drawn directly from FDA-approved prescribing information. NADAC pricing from CMS shows a generic unit cost of $0.29.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 26, 2023
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages