Tapazole Side Effects Center

Last updated on RxList: 2/22/2021
Tapazole Side Effects Center

What Is Tapazole?

Tapazole (methimazole) is an anti-thyroid drug used to treat hyperthyroidism (overactive thyroid). Tapazole is also used before thyroid surgery or radioactive iodine treatment. Tapazole is available in generic form.

What Are Side Effects of Tapazole?

Common side effects of Tapazole include

Tell your doctor if you experience rare but serious side effects of Tapazole including

Dosage for Tapazole

The initial adult dose of Tapazole is between 15-60 mg/day, depending on the severity of the hyperthyroidism, divided into three doses taken 8 hours apart.

What Drugs, Substances, or Supplements Interact with Tapazole?

Some products that may interact with Tapazole include blood thinners (such as warfarin), digoxin, and theophylline.

Tapazole During Pregnancy and Breastfeeding

Tapazole is not recommended for use during the first 3 months of pregnancy and should be used only when prescribed during the last 6 months of pregnancy. Discuss the risks and benefits with your doctor. This medication passes into breast milk. Consult your doctor before breast-feeding.

Additional Information

Our Tapazole Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

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.


Where is the thyroid gland located? See Answer
Tapazole Consumer Information

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

Serious and sometimes fatal infections may occur during treatment with methimazole. Stop using this medicine and call your doctor right away if you have signs of infection such as:

  • sudden weakness or ill feeling, fever, chills, sore throat, cold or flu symptoms;
  • painful mouth sores, pain when swallowing, red or swollen gums; or
  • pale skin, easy bruising, unusual bleeding.

Call your doctor at once if you have:

  • swollen glands in your neck or jaw; or
  • liver problems--nausea, upper stomach pain, itching, tiredness, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

  • nausea, vomiting, upset stomach;
  • headache, dizziness, drowsiness;
  • numbness or tingly feeling;
  • rash, itching, skin discoloration;
  • muscle or joint pain;
  • hair loss; or
  • decreased sense of taste.

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.

Read the entire detailed patient monograph for Tapazole (Methimazole)


Hyperthyroidism Symptoms and Treatment See Slideshow
Tapazole Professional Information


Major adverse reactions (which occur with much less frequency than the minor adverse reactions) include inhibition of myelopoieses (agranulocytosis, granulocytopenia, thrombocytopenia, and aplastic anemia), drug fever, a lupus-like syndrome, insulin autoimmune syndrome (which can result in hypoglycemic coma), hepatitis (jaundice may persist for several weeks after discontinuation of the drug), periarteritis, and hypoprothrombinemia. Nephritis occurs very rarely.

Minor adverse reactions include skin rash, urticaria, nausea, vomiting, epigastric distress, arthralgia, paresthesia, loss of taste, abnormal loss of hair, myalgia, headache, pruritus, drowsiness, neuritis, edema, vertigo, skin pigmentation, jaundice, sialadenopathy, and lymphadenopathy.

Read the entire FDA prescribing information for Tapazole (Methimazole)

© Tapazole Patient Information is supplied by Cerner Multum, Inc. and Tapazole Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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