Does Taking Methimazole Give Cats an Upset Stomach?

Kitty's tummy might not feel so good if she is taking methimazole.
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At times medications can give anyone an upset stomach. If your kitty is throwing up and has lost her appetite after starting on methimazole for hyperthyroidism, the medication is a likely cause. Check to see if you are administering it as directed and consult your vet if the problem persists.

Loss of Appetite and Vomiting

Loss of appetite and throwing up are two of the most common side effects for cats on methimazole. According to Debra Eldredge's book "Pills for Pets: The A to Z Guide," methimazole ideally should be given to your cat with food. Vet Info suggests that coupling the medication with food will disguise the bitter taste that methimazole has, blaming the disagreeable flavor for causing your cat to throw up or stop eating.

Pill Alternative

If taking methimazole in pill form is giving your cat an upset tummy, the medication is also available as a lotion or gel you apply to the inside of her ears. The topical form of methimazole won't make your kitty sick to her stomach and is much easier to administer, especially if dosing your cat tends to be a full-contact sport. Be prepared for the inflated price tag on the topical version of methimazole, though, as it is more expensive than the pills.

Other Side Effects

Even though methimazole is usually prescribed because side effects are rare, they aren't non-existent. In addition to stomach and digestive issues cats taking methimazole have experienced excessive scratching as well as depression and lethargy. If your cat takes methimazole for six months or longer, she can develop an autoimmune disease. Although this side effect isn't as common as scratching and stomach upset, Vet Info reports that 50 percent of cats taking the drug longer than six months will develop an autoimmune condition as a result.

Long-Term Treatment for Hyperthyroidism

If, other than hyperthyroidism, your cat is healthy, her condition may go into remission with long-term treatment. If Fluffy is experiencing side effects from the drug and you are uncomfortable with having her on it for the long haul, radiation is an alternative option. Taking methimazole can stabilize her thyroid hormones, making her eligible for treatment with radioactive iodine. The effect of the radiation is permanent, and typically only one dose is needed.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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