Frequently Asked Question

• What are the most common signs of hyperthyroidism?

  Weight loss 

  Increased appetite 

  Increased drinking and urination

  Poor skin and coat quality (unkempt appearance)

  Behavioral changes such as hyperactivity, irritability, aggression or increased vocalization

  Vomiting and/or diarrhea

• What options are available for medical management?

  The most common medical treatment for feline hyperthyroidism in cats available in the United States is methimazole. Felanorm Oral Solution is the first and only FDA approved oral solution for hyperthyroidism in cats. Methimazole is also available in veterinary-approved and human generic tablets, as well as compounded oral solutions and transdermal gels.

• What is Felanorm^® (methimazole) Oral Solution?

  Felanorm Oral Solution is the only FDA approved oral solution indicated for the treatment of hyperthyroidism in cats. As an FDA-approved formulation, Felanorm Oral Solution ensures precise mg/mL consistency in every bottle—eliminating the potency risks and batch variability of compounded alternatives. Our calibrated syringe, marked in 0.25 mg increments, allows for exact dose adjustments tailored to the specific needs of each patient. Because Felanorm Oral Solution is a honey-flavored oral liquid that is easy to give, it eliminates the owner and patient stress associated with "pilling" cats.

• What are the potential side effects of methimazole?

  As with all drugs, side effects may occur. The following adverse events are based on post approval reporting and are listed in decreasing order of reporting frequency: Anorexia, vomiting, head/facial pruritus or edema, depression/lethargy, weight loss, anemia, elevated liver enzymes, skin lesions, elevated BUN, diarrhea, and thrombocytopenia. In some cases, death (or euthanasia) has been reported as an outcome of the adverse reactions listed above. In some reported cases, the patients recovered after adverse signs were recognized, the drug was withdrawn and veterinary care was applied. Felanorm^® Oral Solution is not for use in pregnant or lactating queens, or cats with renal, hepatic or hematological disorders. Methimazole has anti-vitamin K activity and may induce bleeding diathesis without evidence of thrombocytopenia. Please refer to the product insert for a complete list of warnings, potential side effects and prescribing information associated with Felanorm Oral Solution. To report suspected adverse drug events, for technical assistance or to obtain a copy of the Safety Data Sheet (SDS), contact Virbac at 1-800-338-3659.

  For additional information about adverse drug experience reporting for animal drugs, contact the FDA at 1-888-FDA-VETS or http://www.fda.gov/reportanimalae.

• Are there human health risks with methimazole?

  This product is not for use in humans. Keep out of reach of children. For use in cats only. Wear protective single use, impermeable (e.g., latex or nitrile) gloves when administering the solution. Wash hands with soap and water after administration to avoid exposure to drug. Wear protective gloves to prevent direct contact with litter, feces, urine or vomit of treated cats, and the solution. Wash hands after contact with the litter of treated cats.

  Methimazole is a human teratogen and crosses the placenta, concentrating in the fetal thyroid gland. There is also a high rate of transfer into breast milk. Pregnant women, or women who may become pregnant, and nursing mothers should wear gloves when handling the solution, litter or bodily fluids of treated cats. Individuals with an endocrine disorder that could be impacted by methimazole should use similar precautions. In humans, methimazole may cause vomiting, gastric distress, headache, fever, arthralgia, pruritus, and pancytopenia. In the event of accidental ingestion/overdose, seek medical advice immediately and show the product label to the physician. Avoid skin and oral exposure, including hand-to-mouth contact. Wash any spillages or splatter from the skin immediately. Do not eat, drink, smoke/vape or use smokeless tobacco while handling the product or used litter. Felanorm Oral Solution may cause skin or eye irritation. Avoid eye contact, including hand-to eye contact. In case of accidental eye contact, rinse eyes immediately with clean running water. If irritation develops, seek medical advice. Please refer to the product insert for a complete list of warnings, potential side effects and prescribing information associated with Felanorm Oral Solution.

• Why Honey Flavor? Understanding the Feline Preference and Felanorm^® Oral Solution

  Do cats even like honey flavored methimazole?

  The short answer is yes, but not for the reasons humans do. While humans enjoy honey for its intense sweetness, cats are "sweet blind." They lack the functional taste receptors required to detect sweet flavors. 

  However, the appeal of Felanorm's Oral Solution honey-flavored formulation lies in its ability to mask the natural bitterness of methimazole. Our formulation uses honey flavoring to create a smooth experience that makes administration less stressful for both the cat and the owner. 

• Why is the Felanorm Oral Solution syringe calibrated in mg instead of mL?

  Precision Medicine Made Simple. The Felanorm Oral Solution syringe is calibrated in milligrams (mg) rather than milliliters (mL) to eliminate the "math gap" between the prescription and the administration. By focusing on the active dose of methimazole rather than the volume of liquid, we provide a more intuitive and safer experience for the caregiver.

  The Benefits of mg-Based Dosing

  - Precision Titration: The syringe is calibrated in 0.25 mg increments. This allows you to fine-tune the dosage to keep thyroid levels in the target range while minimizing the risk of breakthrough clinical signs or iatrogenic hypothyroidism. - Reduced Dosing Errors: When the prescription label says "2.5 mg" and the syringe says "2.5 mg," the margin for human error is significantly reduced. - Eliminate Dose Confusion: Felanorm Oral Solution syringes focus on the milligrams (mg) per dose, not the volume (mL). This keeps the owner focused on the veterinarian’s prescribed therapeutic goal, ensuring long-term clinical success and consistent results across every bottle and refill.

• Why use honey if cats can't taste "sweet"?

  Even without sweet receptors, cats are highly sensitive to bitter tastes. By utilizing a honey-flavored aqueous base, we provide a consistent, non-oily texture that cats accept much more readily than traditional tablets. 

  Is there actual honey or sugar in Felanorm Oral Solution?

  No. Felanorm Oral Solution contains no actual honey and no animal proteins, making it an excellent choice for cats on restricted or hydrolyzed diets. This makes Felanorm Oral Solution safe for use in diabetic patients.

• What are some best practices for my clinic?

  To ensure a seamless experience for your clients , keep these three "Best practice guidelines" in mind:

  Optimizing the Felanorm Oral Solution Experience: 
  To ensure seamless home care and accurate dosing for your patients, we recommend these three strategies:

  1. Mg-Based Prescribing:
  To prevent confusion at home, write all prescription instructions in milligrams (e.g., "Give 2.5 mg twice daily"). This creates a perfect 1-to-1 match with the calibration on the Felanorm Oral Solution syringe.

  2. Use the Dedicated Syringe:
  Advise clients to use only the syringe provided with the bottle. Standard 1 mL syringes are graduated in volume, which can lead to calculation errors when trying to match Felanorm Oral Solution's specific mg markings.

  3. Refine the Draw-Up Technique:
  Briefly show clients how to align the flat edge of the plunger with their prescribed dose mark, rather than using the pointed tip, to ensure they are delivering the exact amount of medication intended.

  Quick Tips for Safe Handling:
  Freshness First: Because Felanorm Oral Solution is light-sensitive, avoid pre-filling syringes for future use. This preserves product stability and prevents potential leakage.

  Mess-Free Dosing: The syringe is designed for a secure, tight fit, allowing owners to fully invert the bottle for an easy, leak-free draw.

  Need Support?
  Product Quality: If you suspect a manufacturing defect, please contact our Product Safety & Consulting (PS&C) Team immediately for a prompt resolution. 1-800-338-3659

  Supplies: For syringe replacements due to wear or loss, simply reach out to your Virbac Territory Sales Manager (TSM).