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Methimazole treats hyperthyroidism in cats, a condition in which too much thyroid hormone is produced. It will not cure the disease, but will usually control it if given for the rest of the cat's life.
Methimazole may also be used to protect the kidneys in dogs receiving cisplatin, an anti-cancer drug.
Dogs and Cats.
Controls the symptoms of hyperthyroidism for an improved quality of life
Treats hyperthyroidism without surgery or anesthesia
Affordable per-tablet price!
Methimazole reduces the amount of thyroid hormone produced by the thyroid gland.
Methimazole tablets are given by mouth. The tablet form is very bitter, and it may be difficult to administer. Use a "pill pocket" treat or hide it in your pet's favorite treat. Always follow the dosage instructions provided by your veterinarian. If you have difficulty giving the medication, contact your veterinarian.
Blood levels of thyroid hormone will be checked by your veterinarian at regular intervals, and the dose increased or decreased as needed. The lowest effective dose should be used.
This medication should only be given to the pet for whom it was prescribed.
In most cases methimazole will lower the level of thyroid hormone in hyperthyroid cats. It will generally take 1-3 weeks before the level of thyroid hormone produced by the body will start to decrease. Methimazole will not cure the disease, but will usually control it if given for the rest of the cat's life.
Tablet form.
Please click on "More Information" for possible drug and food interactions with this medication.
Tapazol
meth-EYE-miz-zal
Methimazole
Talk to your veterinarian about what tests and exams may be necessary while your pet is taking Methimazole. Also, discuss what type of outcome is expected. Have your veterinarian explain the other treatment options for hyperthyroidism in cats.
Tell your veterinarian if your pet has a blood disease, liver disease, or autoimmune disease; or may be pregnant, is nursing, or if you intend to breed your pet.
Notify your veterinarian of any other medications or supplements your pet is taking, and also if your pet has had any reactions to previous medications.
If you miss a dose, give it as soon as you remember. If it is almost time for the next dose, skip the one you missed and go back to the regular schedule. Do not give two doses at once.
Methimazole will not cure the disease, but will usually control it if given for the rest of the cat's life. Follow your veterinarian's dosage instructions carefully. Side effects are most common during the first 3 months of treatment. Methimazole has a very bitter taste.
Not for use in pets who are hypersensitive (allergic) to it. Use with extreme caution in pets with anemia, clotting disorders, bleeding, low white cell and platelet counts, or diseases of the immune system, liver, or kidney.
Use with extreme caution in pregnant or lactating animals (females nursing their young). If the mother is receiving Methimazole, place the young on milk replacer after they have received the colostrum (first milk immediately after birth).
In addition to monitoring of thyroid hormone levels, laboratory tests to check liver and kidney function and blood cell counts may be performed before starting treatment and then regularly thereafter.
Side effects tend to occur in the first three months of treatment. If you observe any of the effects listed below, contact your veterinarian immediately.
May see loss of appetite, vomiting, or lethargy. These usually occur within the first two weeks of treatment and may stop even with continuation of treatment.
Less common side effects include liver problems resulting in the above signs plus yellowing of the gums, skin, or eyes; itching of the face, resulting in scratching; or bleeding tendencies. Your veterinarian will determine if these effects necessitate stopping the medication and treating with surgery or radioactive iodine therapy.
Treatment with Methimazole may unmask hidden kidney disease.
Rarely, you may see the development of myasthenia gravis, a neuromuscular disease that severely weakens muscles and may cause difficulty swallowing. If your pet is unusually tired, has a fever (temperature over 103°F), or shows signs of bruising or bleeding, contact your veterinarian immediately.
If your pet experiences an allergic reaction to the medication, signs may include facial swelling, hives, scratching, and sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma. If you observe any of these signs, contact your veterinarian immediately.
Store tablets at room temperature in a tightly closed container protected from light. Refrigerate oral suspension. Keep away from children and pets.
If you know or suspect your pet has had an overdose, contact your veterinarian immediately. Signs of an overdose are similar to the common side effects listed above.
Consult your veterinarian before using Methimazole with any other medications, including vitamins and supplements, since interactions may occur. The drugs clomipramine, amitriptylline, omeprazole, and cyclophosamide may interact with Methimazole and cause severe side effects.
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My cat accidentally took my other cats pills. 2.5mg of methimazole and 1.25mg of prednisolone.
My 16 year old cat has been on methimazole for hyper thyroidism. She currently takes 3.75 mg/day. She has been taking it for about 9 months and her dosage started at 2.5 mg/day. Our vet suggests continuing with this therapy indefinitely, but I see some info online that radiotherapy has better results and we could pay for that if it’s substantially better. Looking for a second informed opinion. Does methimazole have any advantages over radiotherapy? Thank you, David
My 17 yr old cat has been diagnosed with hyperthyroidism. she was started on Methimazole chew treats and now refuses to eat them. I switched to the twist a dose ear Methimazole but if I give that to her daily like the vet suggested, all she does is sleep day and night. It seems to knock her out right after I apply it to her ear. then she starts vomiting her food. I am beginning to think we would be better off going with the radioactive iodine thing. what do you think?
Tony takes methimazole & his thyroid has increased from 2.4 in Feb. to 3.9 this month. My vet does not want to change his methimazole dosage b/c he has gained weight and otherwise is not showing any changes. what behavior changes should I look out for? Only change I’ve noticed in the last few weeks is that he no longer sleeps in bed with me but I have no idea if that’s a Behavior related to thyroid. He has become a little picky with his food but since he’s gained weight, vet not concerned.
Can tony take a lysine supplement with his other meds:amlodipine besylate, methimazole, tumil K potassium supplement and mirtazapine appetite stimulant? He also eats a kidney diet and I wonder if the powder lysine supplement may flavor the food and make him like it better? Thanks!!
Hello, does my 13 y/o cat's bloodwork indicate kidney problems? Please see attachment. He is on methimazole and prednisolone for hyperthyroid and bronchitis. Also, would he benefit from canned sardines in water without add salt? Thank you!
Hi! Tony takes methimazole 5mg, 1/2 in the AM and I/2 in the PM and tumil-k tablets, one in the AM and one in the PM.. my question is, how strict are the administration times ... exactly every 12 hours or can it between every 9-12 hours? Thank you!
Cat diagnosed with Hyperthyroidism. On methimazole but only 3/4 2x/day for 1.5mos. Can't afford to get 3rd blood test to determine dosing cuz just lost my job. His yowling at night is out of control. How can I increase dosage to find proper amount and what signs will I notice when his thyroid is under control?
Hi In the last 3 months Tony’s thyroid level has increase from 1.6 to 2.5. He has been on methimazole for a few years but my vet did not choose to change the dosage with this most recent reading. Is 2.5 a safe thyroid level? Also could you tell me the range in which a phosphorus level should be? Thanks
Hello! Regarding homemade diet for my 15 y/o hyperthyroid and early CKD cat-- 1) Due to hyperthyroidism, is it ok to leave out iodine salt in the recipe? The methimazole keeps the TT4 at around 1.7. 2) Is it true that dark meat has lower phosphorous levels and is a better protein choice than say ground beef? Thank you!
Hi! Tony is on methimazole and his most recent labwork Says his thyroid level is 1.8. Is this is a normal level? I ask because he lays by his water bowl a lot but his kidney levels are good but I was told hyperthyroidism can cause extreme thirst...1.8 is not considered hyperthyroidism right? He also takes amlodipine for High blood pressure. Thx!
My 12 year old cat has hyperthyroidism. He was diagnosed 6 months ago. We treated him with Methimazole for a month and he improved. Shortly after his refill (one month) he started to vomit after every dose. We've tried the y/d food and his levels were still high. I have to decide about radioactive iodine, and I would love an expert opinion. I have more detail, just can't fit it here.