Methimazole
Felimazole (veterinary) · Tapazole (human) · generic methimazole
Methimazole controls an overactive thyroid in cats, one of the commonest diseases of older cats. Felimazole is the veterinary tablet; the human generic is the same drug and a pharmacy can fill a vet’s prescription for it. Compounders also make a transdermal gel applied to the ear for cats that will not take tablets.
What it is used for
Hyperthyroidism in cats causes weight loss despite a big appetite, restlessness, vomiting and a racing heart. Methimazole blocks thyroid hormone production and controls the disease for life; the alternatives are radioactive iodine (a cure, given at specialist centres), surgery, or a prescription diet. The dose is adjusted against thyroid blood tests every few weeks at first and then periodically.
Felimazole is the approved veterinary tablet; the human tablets contain the same drug in strengths that a vet can match. Because many cats resist pills, compounding pharmacies make a gel that is rubbed into the inner ear, which works for most cats although absorption is less predictable.
Safety points that differ from human use
- Vomiting, loss of appetite, facial itching and, rarely, serious blood or liver problems can occur in the first months; the vet checks blood counts and liver values after starting.
- Wear gloves when handling the tablets or the transdermal gel, and keep the gel away from children and pregnant women.
- Treating the thyroid can unmask kidney disease that the high thyroid level was hiding; the vet monitors kidney values as the dose is adjusted.
- Tablets (veterinary and human)
- Compounded transdermal gel (ear)
- Compounded flavoured liquids and small capsules
- 2.5 and 5 mg veterinary tablets
- 5 and 10 mg human tablets
- Compounded gel strengths to the vet’s prescription
Why the cash price varies
Human methimazole is a cheap generic, so a cat on a tablet dose pays mostly the dispensing fee. Felimazole is a veterinary brand at a higher price. The transdermal gel is a compounded product with pharmacist time in it and costs more, varying by compounder; it is a convenience rather than a saving.
How to pay less
- If your cat takes tablets, ask the vet whether a human generic strength (split if needed) is suitable.
- Ask for a ninety-day prescription once the dose is stable.
- If the gel is needed, compare compounders; the strength and the amount per tube differ.
- Upload the prescription to Script Unlock so licensed pharmacies and compounders can quote. You pay the pharmacy directly.
Questions for your vet
- Tablets or transdermal gel for my cat, and how will absorption be checked?
- When are the thyroid, blood count, liver and kidney tests?
- What early side effects mean I should call?
- Is radioactive iodine or the diet an option worth discussing?
- How do I handle the medicine safely?
Rules on refills, transfers and controlled substances differ by state; see pharmacy rules by state.
How Script Unlock gets you a cash price for your pet’s methimazole prescription
Prices on this site come from pharmacies responding to a real prescription. We do not publish estimated, average or "typical" prices, because none of those would be your price.
- 1You upload your prescription
A photo of your your pet’s methimazole prescription prescription is enough. Nothing is sold on the site; you are asking pharmacies to quote.
- 2Licensed pharmacies respond
Pharmacies that Script Unlock has verified see the request and each can reply with its own cash price for your exact drug, strength and quantity.
- 3You choose and pay the pharmacy
You compare the responses, pick a pharmacy, and pay that pharmacy directly when you collect. Script Unlock never takes a patient payment and never sets the price.
Related pet medications
Sources
- FDA Approved Animal Drug Products (Green Book)
- Merck Veterinary Manual
- FDA Orange Book (approved generics and therapeutic equivalence)
- ASPCA Animal Poison Control
Written by the Script Unlock editorial team from the sources above. Not yet reviewed by a veterinarian or veterinary pharmacist. Last checked 2026-10-03. Nothing here replaces your vet\u2019s directions; doses for animals are set by weight and species.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.