About Tapazole Tablets for Hyperthyroidism in Cats

Methimazole (Generic Medication in Tapazole) is Used to Regulate the Feline Thyroid

By Team PetCareRx.

  • Thyroid - Hyperthyroidism

indications for Tapazole

Tapazole is an anti-thyroid medication used for the treatment of hyperthyroidism (overactive thyroid gland) in cats. However, the medication is not FDA approved for use in veterinary medicine. It is also used to ameliorate hyperthyroidism in preparation for subtotal thyroidectomy or for radioactive iodine therapy. Tapazole is used for the treatments where thyroidectomy is contraindicated or not advisable. Tapazole inhibits the formation of thyroid hormone by interacting with iodine.


Do not use the medication in cats with allergy to Tapazole, liver disease, autoimmune disease or blood abnormalities. The medication is not suitable for use in pregnant or nursing animals. The treatment/medication is required for life. The symptoms will reappear on discontinuing the medication.


The medication is available by prescription as tablets. The standard dosage is 5 mg/cat every 8 – 12 hours. In adults, the dosage is 15 mg for mild hyperthyroidism, 30 – 40 mg for moderately severe condition and 60 mg for chronic hyperthyroidism. Make sure to give 3 equal dosages at approximately 8 hour intervals. Repeat blood tests every 3 – 4 weeks until the maintenance dose is reached, and then frequency of blood testing can be set to 3 – 6 months. The maintenance dosage is ½ of the initial dosage.

Brand/Generic equivalents


Side Effects

Tapazole treatment is associated with side effects including nausea, vomiting, lethargy, lack of appetite, arthraglia, lymphadenopathy, loss of taste, hair loss, skin rash, urticaria, and drug fever. In rare instances, serious side effects like agranulocytosis, leukopenia, thrombocytopenia, aplastic anemia and hepatitis are observed. Long-term usage may result in prolonged blood clotting durations, kidney and liver damage, and reduced white blood cell counts.

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Tapazole at a glance

  • 1For cats
  • 2A thyroid medications
  • 3An oral medication
  • 4Treats hyperthyroidism and graves disease

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