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Prescription medication · Anti-Thyroid Agent

propylthiouracil

Also sold as PTU. PTU treats hyperthyroidism, which is when your thyroid gland makes too much thyroid hormone.

Data updated 2026-05-15

1,982
FDA reportsRarely reported
$0.29
Generic price (NADAC)

propylthiouracil (PTU) is a prescription Anti-Thyroid Agent. PTU treats hyperthyroidism, which is when your thyroid gland makes too much thyroid hormone.

Propylthiouracil (PTU) is a medicine that treats an overactive thyroid. It helps to lower the amount of thyroid hormone your body makes.

Verify with FDA → · CMS NADAC pricing →

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 →

View Alternatives → Compare with Another Drug → Full Side Effects Report →

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.

The sections below are summarized in plain English from propylthiouracil's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

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.

This is a plain-language summary of propylthiouracil's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.

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.

This is a plain-language summary of propylthiouracil's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.

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.

This is a plain-language summary of propylthiouracil's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.

Storage

Store PTU tablets at room temperature, between 59° to 86°F (15° to 30°C).

Side Effects (from patient reports)

Based on 1,982 FDA adverse event reports.

Most-reported reactions

Adverse reactions in FAERS for propylthiouracil, by number of reports

reports

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Source FDA Adverse Event Reporting System (FAERS) As of 2025

Reports over time

Adverse-event reports filed for propylthiouracil each year to the FDA Adverse Event Reporting System (FAERS).

050100150200250 20042007201020132016201920222025 203

Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.

Where propylthiouracil sits

propylthiouracil has more FDA adverse-event reports than 12% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.

fewest reports most reports

Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is propylthiouracil; the line is the median (50th percentile).

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

Reports Mentioning Death

170

8.6% of reports — not proof of cause

Hospitalization Reports

907

Top Indication

Hyperthyroidism

Gender Distribution

Female 1,283 (73%)
Male 460 (26%)

Age Distribution

0–17 63
18–44 577
45–64 447
65–74 198
75+ 180

Most Reported Adverse Reactions (FAERS)

# Reaction Reports
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
14 VOMITING 56
15 CARDIAC ARREST 54
16 DIARRHOEA 49
17 PREMATURE BABY 49
18 ACUTE KIDNEY INJURY 48

Reactions in Death Reports

CARDIAC ARREST 23
DEATH 21
MULTIPLE ORGAN DYSFUNCTION SYNDROME 19
ACUTE KIDNEY INJURY 14
RENAL FAILURE 13
CARDIAC FAILURE CONGESTIVE 11
ACUTE HEPATIC FAILURE 10
PNEUMONIA 10
CIRCULATORY COLLAPSE 9
DRUG REACTION WITH EOSINOPHILIA AND SYSTEMIC SYMPTOMS 9

Reactions in Hospitalization Reports

HYPERTHYROIDISM 82
HYPOTENSION 49
NAUSEA 45
AGRANULOCYTOSIS 42
PYREXIA 41
VOMITING 36
ACUTE KIDNEY INJURY 35
ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY POSITIVE VASCULITIS 35
THYROTOXIC CRISIS 35
ACUTE HEPATIC FAILURE 33

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?
Try taking PTU with food to reduce nausea. If nausea persists, contact your doctor.
Can PTU affect my ability to drive or operate machinery?
PTU may cause drowsiness or dizziness in some people. If you experience these side effects, avoid driving or operating machinery.
How long does it take for PTU to start working?
It may take several weeks for PTU to fully control your hyperthyroidism symptoms. Continue taking the medication as prescribed and follow up with your doctor.
What tests will my doctor do while I'm taking PTU?
Your doctor will regularly check your thyroid hormone levels (TSH and free T4) and may also monitor your liver function and white blood cell count.
Can I stop taking PTU once my thyroid levels are normal?
No, do not stop taking PTU without talking to your doctor first. They will determine when it is safe to stop the medication.
What are the symptoms of liver problems I should watch out for?
Symptoms of liver problems include yellowing of the skin or eyes, dark urine, pale stools, severe stomach pain, nausea, vomiting, and fatigue. Contact your doctor immediately if you experience any of these symptoms.
Can PTU cause hair loss?
Yes, PTU can cause hair loss in some people. This is usually temporary and hair growth should return after stopping the medication.
Is it safe to take other medications with PTU?
Tell your doctor about all the medications you are taking, including over-the-counter drugs and supplements, to avoid potential interactions.
What should I do if I think I'm having an allergic reaction to PTU?
If you experience symptoms of an allergic reaction, such as rash, itching, swelling, or difficulty breathing, seek immediate medical attention.
What are the common side effects of propylthiouracil?
The most commonly reported side effects of propylthiouracil include Skin rash, Hives, Nausea, Vomiting, Stomach upset. Based on 1,982 FDA adverse event reports. Always consult your healthcare provider about potential side effects.
What drug class is propylthiouracil?
propylthiouracil belongs to the Anti-Thyroid Agent drug class. It requires a prescription (Rx). PTU treats hyperthyroidism, which is when your thyroid gland makes too much thyroid hormone.
Is propylthiouracil safe during pregnancy?
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. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

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 →

Compare propylthiouracil vs levothyroxine side-by-side →

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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 1,982 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.

Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.

All federal data sources used on this page