Propylthiouracil Overview

Reviewed: August 2, 2013

Propylthiouracil is a presciption medication used to treat hyperthyroidism (overactive thyroid), a condition in which the thyroid gland produces too much thyroid hormone. It is a synthetic hormone used to replace hormone normally produced by the thyroid to regulate energy and metabolism.

This medication comes in tablet form. It is taken 3 times daily, with or without food.

Common side effects of propylthiouracil include nausea, vomiting, and headache. Propylthiouracil can cause drowsiness. Do not drive or operate heavy machinery until you know how this medication affects you.

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Propylthiouracil Cautionary Labels


Uses of Propylthiouracil

Propylthiouracil is a prescription medication used to treat hyperthyroidism (overactive thyroid). It is also taken before thyroid surgery or radioactive iodine surgery to lower thyroid hormone levels.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Propylthiouracil Drug Class

Propylthiouracil is part of the drug class:

Side Effects of Propylthiouracil

Serious side effects have been reported with propylthiouracil. See the "Drug Precautions" section.

The most common side effects of propylthiouracil include:

  • skin rash or hives
  • nausea
  • vomiting
  • upper stomach pain or tenderness
  • joint pain
  • itching or tingling
  • loss or change in taste
  • loss of hair
  • muscle pain
  • headache
  • sleepiness
  • nerve pain
  • swelling (edema)
  • dizziness
  • enlarged salivary glands or enlarged lymph nodes

Tell your doctor if you have any side effect that bothers you or that does not go away.

These are not all of the possible side effects of propylthiouracil. For more information, ask your doctor or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Propylthiouracil Interactions

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

  • a beta blocker such as acebutolol (Sectral), atenolol (Tenormin), betaxolol (Kerlone), bisoprolol (Zebeta), carvedilol (Coreg), esmolol (Brevibloc), labetalol (Trandate), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), nebivolol (Bystolic), penbutolol (Levatol), propranolol (Inderal), sotalol (Betapace), timolol (Blocadren)
  • digoxin (Digitek, Lanoxin)
  • theophylline (Theo-24, Theobid, Theo-Dur, Theolair, Elixophyllin, Elixophylline, Quibron-T, Uniphyl)
  • warfarin (Coumadin, Jantoven)

This is not a complete list of propylthiouracil drug interactions. Ask your doctor or pharmacist for more information.


Propylthiouracil Precautions

Propylthiouracil can cause serious side effects, including:

  • Severe liver problems. In some cases, these liver problems can lead to liver failure, the need for liver transplant, or death. Stop taking propylthiouracil and call your doctor right away if you have:
    • fever
    • loss of appetite
    • nausea
    • vomiting
    • tiredness
    • itchiness
    • pain or tenderness in your right upper stomach area (abdomen)
    • dark (tea colored) urine
    • pale or light colored bowel movements (stools)
    • yellowing of your skin or whites of your eyes
  • low white blood cells and low blood platelets. This can increase the risk of infection or bleeding. Your doctor will monitor for this side effect by using a simple blood test. Tell your doctor right away if you have signs of low blood cells including:
    • infections
    • sore throat
    • fever
    • bruising or bleeding easily

Do not take propylthiouracil if you are allergic to propylthiouracil or any of its ingredients.

Propylthiouracil Food Interactions

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of propylthiouracil, there are no specific foods that you must exclude from your diet when receiving this medication.

Inform MD

Before you take propylthiouracil, tell your doctor if you:

  • plan to have surgery
  • have any other medical conditions
  • are pregnant or breastfeeding

Tell your doctor about all the medicines you take, including prescription and nonprescription medicines, vitamins, and herbal supplements.

Propylthiouracil and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Propylthiouracil falls into category D. It has been shown that use of propylthiouracil in pregnant women caused some babies to be born with problems. However, in some serious situations, the benefit of using this medication may be greater than the risk of harm to the baby.

Proplythiouracil may be the treatment of choice when an antithyroid drug is required during or just prior to the first trimester of pregnancy.

Propylthiouracil and Lactation

Tell your doctor if you are breastfeeding or plan to breastfeed.

Propylthiouracil has been detected in human breast milk. Because of the possibility for adverse reactions in nursing infants from propylthiouracil, a choice should be made whether to stop nursing or to stop use of this medication. The importance of the drug to the mother should be considered.



Propylthiouracil Usage

  • Take propylthiouracil exactly as your doctor tells you to take it.
  • Your doctor may change your dose if needed.
  • Propylthiouracil is usually taken 3 times a day (every 8 hours).
  • If you miss a dose of propylthiouracil, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose. Just take the next dose at your regular time. Do not double your dose.

Propylthiouracil Dosage

Take propylthiouracil exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The propylthiouracil dose your doctor recommends will be based on the following:

  • the severity of your hyperthyroidism
  • other medical conditions you have
  • other medications you are taking
  • how you respond to this medication
  • your age

The usual recommended dose range for propylthiouracil is 100 mg to 150 mg for maintenance therapy.


Propylthiouracil Overdose

If you take too much propylthiouracil, call your local Poison Control Center or go to the nearest hospital emergency room right away.


Other Requirements

  • Store at room temperature between 20° and 25ºC (68° -77ºF)
  • Keep this and all medicines out of the reach of children.

Propylthiouracil FDA Warning

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.

Propylthiouracil should be reserved for patients who can not tolerate methimazole and in whom radioactive iodine therapy or surgery are not appropriate treatments for the management of hyperthyroidism.

Because of the risk of fetal abnormalities associated with methimazole, proplythiouracil may be the treatment of choice when an antithyroid drug is indicated during or just prior to the first trimester of pregnancy.