Uses

What is propylthiouracil used for?

Propylthiouracil is commonly used to treat people with Graves' disease or toxic multinodular goiter who have an overactive thyroid (hyperthyroidism). 

Propylthiouracil can also be used to help reduce symptoms of an overactive thyroid before having surgery to remove the thyroid or radioactive iodine therapy.

Propylthiouracil may also be used for other conditions as determined by your healthcare provider.

How does propylthiouracil work (mechanism of action)?

Propylthiouracil works by blocking your body from making too much thyroid hormone.

How is propylthiouracil supplied (dosage forms)?

Propylthiouracil is available as 50 mg oral tablets that are taken by mouth.

How should I store propylthiouracil?

Propylthiouracil should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of propylthiouracil?

The most common side effects of propylthiouracil are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Nausea or vomiting
  • Upper stomach pain or tenderness
  • Joint, muscle, or nerve pain
  • Itching or tingling 
  • Loss or change in taste
  • Hair loss
  • Headache or dizziness
  • Sleepiness
  • Fluid retention (edema)
  • Enlarged salivary glands or lymph nodes

There may be other side effects of propylthiouracil that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of propylthiouracil?

While less common, the most serious side effects of propylthiouracil are described below, along with what to do if they happen.

Severe Allergic Reactions. Propylthiouracil may cause allergic reactions, which can be serious. Stop taking propylthiouracil and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking propylthiouracil. Stop taking propylthiouracil and call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Blood Disorders. Propylthiouracil can cause blood disorders, such as agranulocytosisaplastic anemia, low platelet levels (thrombocytopenia), and low white blood cell levels (leukopenia). Stop taking propylthiouracil and get help right away if you have any of the following symptoms of blood disorders.

  • Fever, chills or sore throat
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infection
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Swelling of Blood Vessels (Vasculitis). Propylthiouracil can cause inflammation and swelling of your small blood vessels.The swelling can make it hard for blood to reach certain areas of your body. Call your healthcare provider right away if you develop any of the following symptoms.

  • Skin turning red or purple
  • Rash
  • Painful skin or swelling
  • Pink, red, brown or foamy urine (pee)
  • Reduced amount of pee
  • Shortness of breath or coughing up blood

Abnormal Bleeding. People taking propylthiouracil may have an increased risk of bleeding or bruising. You may be at higher risk if you are also taking a blood thinner such as warfarin or undergoing surgery. Tell your healthcare provider if you notice any changes in how easily you bruise or bleed.

Low Thyroid Levels (Hypothyroidism). Propylthiouracil can cause the function of your thyroid gland to change, which can lead to low thyroid levels. Keep all appointments to have your blood checked. Tell your healthcare provider  if you have any of the following signs of low thyroid hormones.

  • Weight gain
  • Feeling cold
  • Tiredness that does not go away or continues to worsen
  • Constipation

Severe Skin Reactions. Propylthiouracil can cause severe skin reactions called Stevens-Johnson Syndrome (SJS)Toxic Epidermal Necrolysis (TEN), and exfoliative dermatitis that can lead to death if not treated. If you develop a rash, stop propylthiouracil and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of a severe skin reaction.

  • Painful red or purple skin that looks burned and peels off
  • Flat red rash or blisters on your skin, mouth, nose, and genitals
  • Red, painful, watery eyes

Immune System Reactions. Propylthiouracil can cause inflammation of your liver, blood vessels, or lymph vessels and cause symptoms that look like a condition called lupus. Stop taking propylthiouracil and call your healthcare provider right away if you develop any of the following symptoms.

  • Rash
  • Joint pain
  • Fever
  • Weakness or unusual tiredness

Warnings & Precautions

Who should not use propylthiouracil?

Allergies to Ingredients. People who are allergic to any of the following should not take propylthiouracil.

  • Propylthiouracil
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific propylthiouracil products they stock.

What should I know about propylthiouracil before using it?

Do not take propylthiouracil unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share propylthiouracil with other people, even if they have the same condition as you. It may harm them.

Keep propylthiouracil out of the reach of children.

Propylthiouracil can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how propylthiouracil affects you.

It is important to keep all of your healthcare appointments while you are taking propylthiouracil, including lab appointments. These lab tests help your healthcare provider know if the medicine is working. 

What should I tell my healthcare provider before using propylthiouracil?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if propylthiouracil is right for you.

In particular, make sure that you discuss any of the following.

Other Medicines and Supplements. Propylthiouracil  may interact with other medicines and supplements. Before taking propylthiouracil, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Surgery. Tell your healthcare provider if you have any upcoming surgeries.

Pregnancy. Propylthiouracil may cause harm to an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. 

Breastfeeding. Propylthiouracil passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take propylthiouracil while breastfeeding.

Interactions

Does propylthiouracil interact with foods or drinks?

There are no known interactions between propylthiouracil and foods or drinks.

It is unknown if drinking alcohol will affect propylthiouracil.

Does propylthiouracil interact with other medicines (drug interactions)?

Propylthiouracil may interact with certain medicines. Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

 In particular, make sure that you discuss if you are using any of the following before taking propylthiouracil.

  • Warfarin, which is a blood thinner

  • A beta-blocker, such as metoprolol (Lopressor, Toprol XL, and others), atenolol (Tenormin), or propranolol (Inderal LA, Innopran XL), which is a medicine that may be used for certain heart conditions or to reduce blood pressure

  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure

  • Theophylline (Theo-24), which is a medicine used for asthma or other chronic lung conditions

This may not be a complete list of medicines that can interact with propylthiouracil. Always check with your healthcare provider.

Does Propylthiouracil interact with other drugs you are taking?
Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much propylthiouracil?

If you or someone else has used too much propylthiouracil, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of propylthiouracil?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

 

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