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Carbimazole is a medication used to treat an overactive thyroid (hyperthyroidism) in cats and other animals. Carbimazole lowers thyroid hormone levels.
It is used off label (extra label) in veterinary medicine in Canada and the United States. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions very carefully, as they may be significantly different from those on the label.
This medication should start to take effect within a few days, although effects may not be noticeable right away.
If you miss a dose, give it as soon as you remember, and then wait the recommended amount of time between doses. Do not give the pet two doses at once.
Carbimazole may cause the following side effects:
The following reactions are rare, but if they occur, contact your veterinarian immediately:
Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment. Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This medication is short-acting, meaning that effects will last less than 24 hours, though effects may last longer in pets with kidney or liver disease.
Carbimazole should NOT BE USED in animals who:
Carbimazole should be USED WITH CAUTION in pets who:
Certain medications should be USED WITH CAUTION when given with carbimazole, including:
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Adverse effects should be reported to the FDA or Health Canada.
© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Jan 13, 2025.
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2801 Keele St. Unit #101 Downsview, ON M3M 2G6
Phone: 416- 633-2255
Fax: 416-633-2305
E-Mail: downsviewveterinary@bellnet.ca
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