Tapazol: Medical Uses, Mechanism of Action, Side Effects, Interactions and Contraindications

It is an antithyroid drug that is used to treat hyperthyroidism.

The tapazole, also called methimazole, belongs to the antithyroid medication class. It prevents the thyroid gland from producing too much thyroid hormone, but it does not interfere with the actions of the thyroid hormone.

It may take weeks or months before tapazole has full effect on overactive thyroid symptoms. During this period, other medications can be used to control the symptoms.

Medical uses

Topical is a medication used to treat hyperthyroidism, as in Graves’ disease, a condition that occurs when the thyroid gland begins to produce an excess of thyroid hormone.

The medication can also be taken before thyroid surgery to reduce thyroid hormone levels and minimize the effects of thyroid manipulation.

Continue to use this medication even if you feel well or no longer have symptoms of hyperthyroidism. You may need to continue taking long-term methimazole to control your condition. Stopping the pill may cause your symptoms to reappear.

Mechanism of action

The tapazole inhibits the enzyme thyroperoxidase, which usually acts in the synthesis of thyroid hormone by oxidizing the anion iodide (I-) to iodine (I2), hipoyudado acid, hypoiodate bound to the enzyme facilitates the addition of iodine to tyrosine residues in the precursor of the hormone thyroglobulin, a necessary step in the synthesis of triiodothyronine (T3) and thyroxine (T4).


Side effects

It is essential to control any symptoms of fever or sore throat while taking tapazole; this could indicate the development of agranulocytosis, a rare but severe side effect that results from a decrease in the white blood cell count (to be specific, neutropenia, a neutrophil deficiency).

Some known side effects include:

  • Acne.
  • Itch.
  • Abnormal hair loss
  • Pigmentation of the skin.
  • Urticaria.
  • Belly pain (acidity)
  • Sickness.
  • Vomiting
  • Loss of taste
  • Strange sensations (tingling, burning, and oppression).
  • Swelling.
  • Numbness.
  • Pain in the joints and muscles.
  • Headache.
  • Drowsiness.
  • Dizziness

Less common but more severe side effects include:

  • Decrease in platelet count ( thrombocytopenia ).
  • Decrease in white blood cells (agranulocytosis).
  • Aplasia cutis congenital (prenatal exposure).
  • Enlargement of the thyroid gland (prenatal exposure).

Symptoms and signs of agranulocytosis include throat infections, gastrointestinal tract infections, and skin with a general feeling of illness and fever.

Thrombocytopenia can cause problems with excessive bleeding because platelets are essential for blood clotting.

What medications or supplements interact with tapazole?

People who take anticoagulants such as warfarin, diabetes medications, digoxin(Lanoxin), theophylline, and vitamins may have adverse effects.


People who have ever had a blood disease, such as decreased white blood cells ( leukopenia ), decreased platelets (thrombocytopenia) or aplastic anemia, or liver disease (hepatitis, jaundice ) may have problems taking tapazole.

If you need to undergo surgery, inform the surgeon in advance that you are using this medication, as its anticoagulant effect may cause bleeding during the operation.

Methimazole can reduce blood cells that help your body fight infections. This can make it easier for you to bleed from an injury or get sick from being around other suffering people. You may need to check your blood often. Visit your doctor regularly.

Do not receive a vaccine while being treated with methimazole, and avoid coming into contact with anyone who has recently received a live vaccine. There is a possibility that the virus could be transmitted to you.

Is it safe to take methimazole if I am pregnant or breastfeeding?

Do not use methimazole if you are pregnant or plan to be pregnant. It could harm the unborn baby.

Methimazole is excreted in breast milk and can cause harm to the baby.

When to call the doctor?

Call your doctor or go to the emergency room if you have any of the following symptoms:

  • Difficult breathing
  • Rochas
  • Swelling of the face, lips, throat, or tongue.
  • Fever.
  • Shaking chills.
  • Sore throat.
  • Pains in the body
  • Bruising or easy bleeding.
  • Unusual weakness
  • Blood in your urine or stool
  • Severe rash with blisters.
  • Peeling and a red rash.
  • Loss of appetite
  • Dark urine.
  • Chairs of clay color.
  • Jaundice .