What is Felanorm for Cats?
Felanorm, methimazole, is a recently approved prescription medication used for the treatment of hyperthyroidism in cats. Felanorm is the first generic methimazole oral solution approved by the FDA for use in cats with hyperthyroidism. Learn more. This medication works by blocking thyroid peroxidase, an important enzyme for producing thyroid hormones. By inhibiting this enzyme, Felanorm allows cats who produce unusually large amounts of thyroid hormone to go back down to normal levels and live a better life.
- Felanorm is a honey-flavored oral solution containing the active ingredient, methimazole.
- It is is typically given every 12 hours.
- It can be given with or without food.
- Felanorm is available in a 30 mL bottle or a 100 mL bottle.
- It contains a 1-mL dosing syringe that is marked per milligram for easy dosing.
Warning Signs of Hyperthyroidism in Cats
Hyperthyroidism is caused by the thyroid gland producing too much thyroid hormone. Hyperthyroidism is diagnosed more commonly in older cats and certain breeds of cats. Some common warning signs include:
- Weight loss
- Increased appetite
- Increased thirst
- Restlessness
- Rapid heart rate
Side Effects of Felanorm for Cats
Methimazole is usually well tolerated in cats, but side effects can occur. Some common side effects of Felanorm include: changes in appetite (increase or decrease), lack of energy, vomiting, diarrhea or loose stool, skin lesions, itching, and abnormal vocalizations. Cats taking this medication should receive regular checkups with their veterinarian and be monitored for side effects.
Does Felanorm Methimazole for Cats Require a Prescription?
Felanorm can only be obtained with a prescription from a licensed veterinarian. This is because professional veterinary expertise is necessary to diagnose hyperthyroidism in cats and to determine whether methimazole is the right treatment. Continued veterinary check ups are necessary to ensure the dosage remains suitable for controlling the cat’s hyperthyroidism, as this condition can progress over time.
About the Author
This article was written by VetRxDirect pharmacy intern Mitch.
My two cats are Rigby (left) and Gus (right). They are both five years old and are each other’s best friends. Gus likes to steal whole slices of pizza when no one is looking and likes smelling stinky shoes. Rigby likes sneaking into places and is VERY friendly/chatty. -Mitchell, PharmD Candidate 2025, University of Iowa College of Pharmacy