Methimazole is the most common medication prescribed to treat feline hyperthyroidism. Side effects of methimazole include lethargy, loss of appetite, vomiting, facial itching, increased liver enzymes, and decreased blood cells. If these side effects occur, stop the medication and call us. The blood should be rechecked 2 to 4 weeks after starting the medication to evaluate not only the thyroid level, but the kidneys, liver enzymes, and blood cells.
Felimazole is coated methimazole tablets.