Methimazole is an oral medication that works on the thyroid gland and inhibits the production of thyroid hormones.
Methimazole is used to treat hyperthyroidism (overactive thyroid) in cats.
This medication does not have an FDA approved indication for use in animals, but it is a common and acceptable practice for veterinarians to prescribe this human medication for use in animals. Do not use on pregnant, breeding, or nursing animals. Do not administer a "live" vaccine to your pet while the pet is being treated with methimazole. Make sure to tell your veterinarian what other medication you are giving to your pet. Quite often your veterinarian may prescribe two different medications, and a drug interaction may be anticipated. In this case, your veterinarian may vary the dose and/or monitor your pet more closely. Anticoagulants can potentially interact with methimazole. Contact your veterinarian if your pet experiences any unusual reactions when different medications are given together. Do not stop giving this medication to your pet unless directed by your veterinarian. Allergic reactions to medications may occur. Be sure to inform VetSource and your veterinarian if your pet has any known drug sensitivities or allergies. If your pet displays symptoms of an allergic reaction, call your veterinarian immediately or go to a veterinary emergency clinic. Symptoms may include but are not limited to: swollen lips, tongue, face, airways; difficulty breathing; agitation; profuse salivation; vomiting; widespread hives and itching.
Possible side effects may include loss of appetite, vomiting and drowsiness and usually decrease over time. Notify your veterinarian if symptoms are troublesome and continue. Other side effects may occur. If the pet experiences anything unusual, contact your veterinarian.
Methimazole should be given orally as directed by your veterinarian. Try to give this medication at about the same time each day. Wash hands after handling this medication or after changing litter box of treated cats. Wear gloves to administer this medication if pregnant or breastfeeding.