Drugs Home > Precautions and Warnings With PTU

PTU is not an appropriate medication for everyone. In fact, it carries a high risk of liver damage, so it is typically only reserved for women who are in the first trimester of pregnancy, or people who cannot take another medication. PTU warnings and precautions also apply to people with certain medical conditions or allergies.

What Should I Tell My Healthcare Provider?

Prior to taking PTU (propylthiouracil), tell your healthcare provider if you have:
  • Liver disease, such as hepatitis, cirrhosis, or liver failure
  • A bleeding disorder
  • Any allergies, including to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
  • Pregnant or thinking of becoming pregnant
  • Breastfeeding.
Make sure to tell your healthcare provider about all of the medicines you take, including prescription and nonprescription medications, vitamins, and herbal supplements.

Specific PTU Warnings and Precautions

Some safety precautions and warnings to be aware of prior to taking PTU include the following:
  • This medicine can cause serious liver reactions, which may result in death. Let your healthcare provider know right away if you develop signs of liver problems, such as:
    • Yellow eyes or skin (jaundice)
    • Upper-right abdominal pain (stomach pain)
    • Itching
    • Loss of appetite
    • Elevated liver enzymes (found using a blood test).
  • Because PTU is more likely to cause liver failure compared to methimazole, another antithyroid medication, it should be used only for people allergic to or unable to tolerate methimazole, if no other treatments are available, or for women in the first trimester of pregnancy.
  • PTU can cause low blood cells, such as low white blood cells and low blood platelets. These conditions can be quite serious. Your healthcare provider should monitor your blood counts during treatment (using a simple blood test) to check for such problems. Let your healthcare provider know if you develop any signs of such problems, such as infections, sore throat, fever, or easy bruising or bleeding.
  • You should avoid alcohol while taking this medication, as additive effects (such as increased drowsiness, confusion, or memory loss) could occur.
  • PTU could react with other medications (see Drug Interactions With PTU).
  • This is a pregnancy Category D medication, which means it presents a definite risk to a woman's pregnancy. Check with your healthcare provider before taking this drug when pregnant (see Propylthiouracil and Pregnancy).
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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