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Generic Name: propylthiouracil (PRO pil THYE oh URE a sil)
Brand Name:

What is propylthiouracil?

Propylthiouracil prevents the thyroid gland from producing too much thyroid hormone.

Propylthiouracil is used to treat hyperthyroidism (overactive thyroid), Graves' disease, or toxic goiter (enlarged thyroid). This medicine is sometimes given to control symptoms just before you undergo thyroid surgery or treatment with radioactive iodine.

Propylthiouracil is for use only if your condition cannot be treated with another thyroid medication, or when surgery or radioactive iodine are not good treatment options for you.

Propylthiouracil may also be used for other purposes not listed in this medication guide.

Important Information

Propylthiouracil can cause liver damage in both adults and children. Liver failure can be fatal or may require a liver transplant. Stop taking propylthiouracil and call your doctor right away if you have signs of liver damage: fever, itching, nausea, vomiting, upper stomach pain, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Do not use propylthiouracil if you are pregnant.

Before taking this medicine

You should not use propylthiouracil if you are allergic to it.

To make sure propylthiouracil is safe for you, tell your doctor if:

  • you have liver problems;

  • you have a weak immune system; or

  • you need to have surgery.

Do not use propylthiouracil if you are pregnant, and tell your doctor right away if you become pregnant while using this medicine. Propylthiouracil can harm an unborn baby, or cause serious liver problems in the mother.

You may need to use another medication during pregnancy. Talk with your doctor if you plan to become pregnant while taking propylthiouracil.

Propylthiouracil can pass into breast milk and may harm a nursing baby. Do not use propylthiouracil while you are breast-feeding a baby.

In most cases, propylthiouracil should not be used by anyone younger than 18 years old. Do not give this medicine to a child without your doctor's advice.

How should I take propylthiouracil?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Use propylthiouracil regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.

Propylthiouracil can lower blood cells that help your body fight infections and help your blood to clot. This can make it easier for you to bleed from an injury or get sick from being around others who are ill.

Call your doctor if you have unusual bruising or bleeding, or signs of infection (fever, chills, sore throat).

While using propylthiouracil, you will need frequent blood tests to check your thyroid function.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, stomach pain, headache, joint pain, fever, chills, itching, swelling, loss of appetite, and feeling restless or drowsy.

What should I avoid while taking propylthiouracil?

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

Propylthiouracil side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Propylthiouracil can cause liver damage in both adults and children (especially during the first 6 months of treatment). Liver failure can be fatal or may require a liver transplant. Stop taking propylthiouracil and call your doctor right away if you have signs of liver damage:

  • nausea, vomiting, upper stomach pain;

  • itching;

  • fever, tiredness;

  • loss of appetite;

  • dark urine, clay-colored stools; or

  • jaundice (yellowing of the skin or eyes).

Also call your doctor at once if you have:

  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

  • sudden chest pain or discomfort, wheezing, dry cough, feeling short of breath;

  • little or no urination;

  • low white blood cell counts--sudden weakness or ill feeling, fever, chills, sore throat, mouth sores, red or swollen gums, trouble swallowing;

  • lupus-like syndrome--joint pain or swelling with fever, swollen glands, muscle aches, chest pain, vomiting, unusual thoughts or behavior, and patchy skin color;

  • signs of underactive thyroid--extreme tired feeling, dry skin, joint pain or stiffness, muscle pain or weakness, hoarse voice, feeling more sensitive to cold temperatures, weight gain; or

  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • nausea, vomiting, stomach pain;

  • swollen glands;

  • tingling or burning pain;

  • headache, drowsiness, dizziness;

  • swelling in your hands or feet;

  • mild rash or itching;

  • joint or muscle pain;

  • decreased sense of taste; or

  • hair loss.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Propylthiouracil dosing information

Usual Adult Dose for Hyperthyroidism:

-INITIAL DOSE: 100 mg orally every 8 hours (300 mg daily); some patients may require 400 mg orally daily in 3 divided doses; rarely, a patient may require 600 to 900 mg orally daily in 3 divided doses
-MAINTENANCE DOSE: 100 to 150 mg orally daily in 3 equally divided doses every 8 hours

Use: 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

Usual Adult Dose for Thyroid Storm:

-INITIAL DOSE: 100 mg orally every 8 hours (300 mg daily); some patients may require 400 mg orally daily in 3 divided doses; rarely, a patient may require 600 to 900 mg orally daily in 3 divided doses
-MAINTENANCE DOSE: 100 to 150 mg orally daily in 3 equally divided doses every 8 hours

Use: To ameliorate symptoms of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy in patients who are intolerant of methimazole

Usual Pediatric Dose for Hyperthyroidism:

This drug is generally not recommended for use in pediatric patients except when other therapies are not an option.
-Patients younger than 6 years: Not recommended
-Patients 6 years or older: 50 mg orally daily with careful upward titration based on clinical response and evaluation of TSH and free T4 levels

-Although cases of severe liver injury have been reported with doses as low as 50 mg per day, most cases were associated with doses of 300 mg per day and higher.

Use: Hyperthyroidism

What other drugs will affect propylthiouracil?

Tell your doctor about all your current medicines and any you start or stop using, especially:

This list is not complete. Other drugs may interact with propylthiouracil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Where can I get more information?

  • Your pharmacist can provide more information about propylthiouracil.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 3.01.

Date modified: March 06, 2018
Last reviewed: March 14, 2016