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$5.57 $3.79 per tablet
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Product Info

What is Tapazole?

Tapazole is used to treat hyperthyroidism in cats. Tapazole is sold per tablet and requires a prescription from your veterinarian.




  • Effectively treats hyperthyroidism in cats
  • Rapid results
  • Lower incidence of adverse side effects than propylthiouracil
  • No reported side effects
  • Sold per tablet

How does Tapazole work?

Hyperthyroidism is a condition that occurs when the thyroid gland produces too much thyroid hormone. Tapazole inhibits the production of thyroid hormones.


Blood tests must be done to check for proper dosage. Do not use in pregnant or nursing pets. Do not give your pet a live vaccine while giving Tapazole. Contact your veterinarian immediately if your pet develops signs of an infection.

Brand Name:

Tapazole (AAI Pharma)

Generic Name:


What is the most important thing I should know about Tapazole?

Tapazole prevents the thyroid gland from producing too much thyroid hormone. Tapazole is used to treat overactive thyroid (hyperthyroidism). It is also used before thyroid surgery or radioactive iodine treatment. Tapazole may also be used for purposes other than those listed in this guide. Tapazole is a prescription medication not FDA approved for veterinary use; however, it is a commonly accepted practice for veterinarians to use this medication in cats. Tapazole is available as a 5 mg scored tablet. Do not give Tapazole to pregnant or nursing pets. Tapazole can increase the risk of bleeding. Tapazole can lower the blood cells that help fight infections. Your veterinarian will need to give blood tests on a regular basis to be sure these blood cells do not get too low. Do not give the pet a "live" vaccine while the pet is taking Tapazole. Tapazole is need for the life of your pet. If the medication is stopped, the symptoms will reappear.

What should I discuss with my veterinarian before giving Tapazole to my pet?

Tell your veterinarian if your pet has an allergy to Tapazole or if your pet has liver disease, a blood cell disorder, or a weak immune system. Tell your veterinarian if the pet is pregnant or nursing. Inform your veterinarian of any other medications, including vitamins and supplements your pet may be taking while receiving Tapazole.

How should Tapazole be given?

Give this medication exactly as directed by your veterinarian. The usual initial dose for cats is 5mg every 8 to 12 hours. Do not give in larger amount, or give it for longer than recommended by your veterinarian. Follow the directions on the prescription label. If you do not understand the directions ask the pharmacist or veterinarian to explain them to you. Tapazole can be given with or without food. Allow plenty of water for the pet to drink.

What are the potential side effects of Tapazole?

If any of the following serious side effects occur, stop giving Tapazole and seek emergency veterinary medical attention; an allergic reaction (difficulty breathing; swelling of the lips; tongue or face; hives). Stop giving Tapazole and contact your veterinarian at once if your pet develops any of these serious side effects; fever, chills, body aches; easy bruising or bleeding, unusual weakness; blood in the urine or stools; severe blistering, peeling, and skin rash; nausea, low fever, loss of appetite, dark urine, jaundice. Other less serious side effects may occur. Continue giving Tapazole and talk to your veterinarian if your pet experiences headache, drowsiness, dizziness; mild nausea, or vomiting; itching; muscle, joint, or nerve pain; swelling; hair loss. Other side effects may also occur. Talk to your veterinarian about any side effect that seems unusual or bothersome to your pet.

What happens if I miss giving a dose of Tapazole?

Give the missed dose as soon as you remember during the same day. However, if you don't remember until the next day, skip the dose you missed and give only the next regularly scheduled dose. Do not give a double dose of the medication.

What happens if I overdose my pet on Tapazole?

Seek emergency veterinary medical treatment. Symptoms of Tapazole overdose may include nausea, vomiting, upset stomach, joint pain, headache, fever, itching, swelling, and easy bruising or bleeding.

What should I avoid while giving Tapazole to my pet?

Do not give the pet a "live" vaccine while the pet is taking Tapazole. Contact your veterinarian at once if your pet develops signs of an infection.

What other drugs will affect Tapazole?

Tell your veterinarian if your pet is taking theophylline (Theo-Dur), warfarin (Coumadin), digoxin (Lanoxin), a beta blocker such as atenolol (Tenormin), metoprolol (Lopressor), or propranolol (Inderal). Drugs other than those listed may also interact with Tapazole. Talk to your veterinarian or pharmacist before giving any prescription or over the counter medicines.

How to Use

Tapazole Directions:

  • Tapazole is a prescription medication used by veterinarians to treat overactive (hyper) thyroid in cats.
  • Tapazole is not FDA approved for use in veterinary medicine; however, it is a commonly accepted practice for veterinarians to prescribe this medication for cats.
  • Tapazole is also used before thyroid surgery or radioactive iodine treatment.
  • Periodic blood tests will be necessary while the cat is taking this medication.

Do not use in pregnant or nursing pets. Tapazole can be given with or without food.

All weights
The usual initial dose varies from 2.5-5 mg two or three times a day. Periodic blood testing is required to monitor liver function and for any toxic effects on blood cells.
Do not use!
Do not use!

Store Tapazole at room temperature away from moisture and heat.


Tapazole Ingredients:

Active Ingredient (per tablet)
5 mg

Other Ingredients: Lactose Monohydrate, Magnesium Stearate, Starch (corn), Pregelatinized Starch and Talc.

Customer Reviews
Tapazole is rated 3.6 out of 5 by 12.
Rated 1 out of 5 by from dangerous side-effects I didn't think my 16 yo cat had a problem at all, just went to the vet for routine stuff. The vet said he was mildly hyperthyroid and that could get to be a problem and put him on the drug at 2.5 mg per day. After one month, his liver tests showed complete failure. He is still alive due to a lot of injections but he won't eat at all, and he's too old to anesthetize and tube feed. So now my cat, who appeared completely healthy and active, will probably be put to sleep this week. Unless a cat is severely hyperthyroid, I would not use this drug.
Date published: 2014-05-12
Rated 5 out of 5 by from Tapazole 5mg My 19 year old cat Abby has been on Tapazole 5mg for several years now and doing well. When I get up in the morning, she is there waiting for me to give her the pill in the pill pocket and won't eat until she gets it. :) She takes two a day. But unfortunately, the price has more than doubled and I am now looking to see if I can purchase this medication at a lower cost or possibly try the generic. I didn't have any choice. I see other costs listed here and it is much lower. Have to talk to Pet Meds and find out why. Not happy. I have three other cats and it is expensive.
Date published: 2013-11-25
Rated 5 out of 5 by from Tapazole great product My 16 year old cat lady was diagnosed with Hyperthyroidism about one month ago. Her T4 and Free T4 were high. We started her on 2.5mg for two weeks then checked her blood results. Her blood results have improved in that they are starting to go down. She will be on 5mg for the next month and then we are going to take her blood again to see if the higher dose will bring down T4 and Free T4 down to normal and keep it that way. Did not want to start her on too high a dose as it can cause liver and kidney problems. She is doing fine on this medication and actually has gained some weight back. She is much more relaxed and not so nervous. Also Tapazole is not generic Methimazole is. Will try her on Methimazole later on if cost is prohibited. Also I put the tablet into her moist food that i give once a day and it goes right down and no stress to her. Also you can't beat the prices of 1-800-pet meds. The vet is a lot more expensive but I do love my vets-they are very caring and truly want to do what is best for my pet.
Date published: 2012-03-29
Rated 5 out of 5 by from great drug i have been using this product for my hyperthyroid 16 year old cat for 3 weeks initial blood results were off the chart after 3 weeks on 1 pill 2 X a day all functions are now normal and he is calm and happy; dosage has now been reduced and we look forward to a healthy, happy cat for a few more years.
Date published: 2011-08-28
Rated 5 out of 5 by from Tapazole My 16 year old female cat lost half her body weight (went from 14 pounds to under 7) due to hyperthyroidism. She went on Tapazole, which literally saved her life! She has a ravanous appetite, but has regained a lot of the weight and is radically improved. We no longer feel her bony spine when we pet her back. This medication saved her life! She's been on the brand name, but am going to try to switch her to the generic due to the high cost. 5 stars for effectiveness and overall rating, and 1 star for taste. We have to force feed her the pill twice daily.
Date published: 2010-03-29
Rated 5 out of 5 by from Price ?? I brought the prescription into Wal-Mart and got 30 tablets, 5MG., for about $17.00...
Date published: 2010-03-07
Rated 5 out of 5 by from Wow! INCREDIBLE PRICES at PetMeds Our vet just charged us $70.30 for this EXACT SAME medicine (same number of tabs) ! ! ! ! I also discovered the generic of Tapezol is: 50 cents (500 tabs - generic) vs vet price: $70.30 (100 tabs) ! ! ! ! ! ! We'll never buy pet medicine from our vet again! THANK YOU PETMEDS!!!!!!!!!!
Date published: 2010-02-09
Rated 1 out of 5 by from Cat turned into Zombie... Our cat had too many side effects with this medication....scratching around face and ears, vomiting.... she looked like a zombie! We switched to Carbimazole which is converted to methimazole in the body and is less likely to cause side effects. We were able to get it at our local compounding pharmacy. Her weight is steady and no side effects!
Date published: 2010-01-15
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Handling Tapazole

Do I need to take any precautions while handling tapazole?
Asked by: mittens
If you are using the gel form of TAPAZOLE ( METHIMAZOLE ) than you should use finger cots or gloves to avoid the medication possible being absorbed through your skin. On the tablet form there is no need to wear gloves except if you are pregnant.
Answered by: Linda petmeds pharmacist
Date published: 2016-06-29

tapazole diet for cats

Are there any food restrictions when my Frankie takes Tapazole?
Asked by: Ron
There are no food restrictions with Tapazole, but if you notice any unusual reactions with certain foods report it immediately to your veterinarian.
Answered by: Janine M./Pharmacist
Date published: 2017-08-08

How can I tell if my pet has a headache??

side affect may be headache, nausea, dizziness, How do I know if my cat has a headache or other symtoms??
Asked by: LA
There is no real way to tell if the cat has a headache, but if the cat stops eating or starts vomiting that could indicate that they are suffering from nausea or dizziness.
Answered by: Janine M./Pharmacist
Date published: 2013-10-22

where are the stability studies? and who did them?d

Asked by: todge
We use an outside pharmacy to make the compounded medications. Pharmacists have reference books and compounding websites, such as PCCA, that they subscribe to, to be able to determine stability.
Answered by: K Paterson
Date published: 2013-10-22

Compounded tapazole in liquid form was just said to be good for 60 days. Is there any scientific documentation to back that up?n

Asked by: todge
There have been stability studies conducted to determine how long these compounds are stable for.
Answered by: Janine/Pharmacist
Date published: 2013-10-22

In compounded form how long is liquid tapazole good for?

Asked by: todge
It has a 60 day expiration date.
Answered by: Kelly P. Pharmacist
Date published: 2013-10-22

do you sell the tapazole "gel pen" and how does it work:?

Asked by: Cynthia
I am sorry we do not carry that product at this time. We will look into providing it.
Answered by: Laura PetMed Pro
Date published: 2013-10-22

Do you need a copy of the prescription?

My vet prescribed Tapazole 5 mg for my cat. Do you require any documentation before I can order from you?
Asked by: glydeur
Great question. For prescription products we will get your pet's and vet's information from you when you place the order. We will contact your vet directly to get the prescription, and mail your order to you.
Answered by: Randy, PetMed Pro
Date published: 2013-10-22
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