Felimazole (Methimazole) Tablets for Feline Hyperthyroidism, 5 mg

FDA-Approved Methimazole Tablet for Hyperthyroidism in Cats

Product Description

Felimazole Coated Tablets 5 mg is an FDA-approved, prescription-only tablet for cats diagnosed with hyperthyroidism. Each small sugar-coated tablet contains 5 mg of methimazole, which works by slowing down thyroid hormone production at the source. Treatment starts at 2.5 mg twice a day and is fine-tuned from there based on bloodwork and your cat's progress. The 5 mg strength is typically used once higher doses are needed.

Benefits

• FDA-Approved for Cats: Felimazole is an FDA-approved veterinary methimazole tablet made specifically for cats and their unique thyroid health needs.
• Controls Hyperthyroidism: Blocks thyroid peroxidase, reducing hormone production and bringing elevated T4 levels back into the normal range.
• Improves Quality of Life: Returns your cat's metabolic rate to normal, easing signs like weight loss, increased appetite, hyperactivity, and excessive thirst.
• Prevents Secondary Complications: Keeping hyperthyroidism under control helps protect cats from serious conditions like hypertrophic cardiomyopathy and high blood pressure.
• Flexible Dose Titration: The 5 mg tablet allows adjustments in 2.5 mg steps, giving your veterinarian precise control over each cat's thyroid management plan.
• Easy to Administer: Small sugar-coated tablets can be given directly or tucked into a small amount of food to make each dose easier for your cat to take.

Ingredients

Composition Table

Other Ingredients

Polyethylene Glycol, Sugar Coating

How to Use

Dosage & Administration Instructions

• Prescription Required: Federal law limits this drug to use by or on the order of a licensed veterinarian only.
• For Cats Only: This medication is for oral use in cats only and must never be given to humans or other animal species.
• Starting Dose: Start at 2.5 mg every 12 hours; the 5 mg tablet comes into use as doses are increased in 2.5 mg steps based on bloodwork results.
• Maximum Daily Dose: The total daily amount should not go beyond 20 mg, and no single dose should exceed 10 mg at one time.
• Give With or Without Food: Tablets can be given on their own or hidden in a little food; just make sure your cat takes the full dose.
• Do Not Break or Crush: Always give the tablet whole to keep the sugar coating intact and avoid unnecessary drug exposure.
• Bloodwork Before Starting: Before your cat starts this medication, your vet will need a full blood count, biochemistry panel, and total T4 reading to set a safe baseline.
• Monitoring Schedule: Your vet will schedule follow-up bloodwork at the 3-week and 6-week marks, then move to checks every 3 months to make sure everything stays on track.
• Missed Dose: If a dose gets missed, give it as soon as you notice; never give two doses together to make up for a missed one.

Disclaimer: This dosage information is provided by the manufacturer. Always consult your veterinarian before administering or adjusting any supplement for your pet.

Additional Information

Precautions

• Hypersensitivity Contraindication: Do not use in cats with a known sensitivity to methimazole, carbimazole, or the inactive ingredient polyethylene glycol.
• Liver or Kidney Disease: Avoid use in cats with primary liver disease or kidney failure, as treating hyperthyroidism can bring underlying kidney disease to the surface.
• Autoimmune or Blood Disorders: Not suitable for cats with autoimmune conditions or blood disorders such as anemia, neutropenia, lymphopenia, or low platelet counts.
• Pregnant or Lactating Cats: Methimazole passes through the placenta and concentrates in fetal thyroid tissue and transfers heavily into breast milk; never use in pregnant or nursing queens.
• Drug Interactions: Methimazole can reduce the effectiveness of phenobarbital, strengthen the effect of anticoagulants, and interact with beta-blockers, digitalis glycosides, and theophylline.
• Anthelmintic Interaction: When used alongside benzimidazole dewormers like fenbendazole, methimazole slows their breakdown in the liver, raising their levels in the bloodstream.
• Human Handling Precautions: Wear gloves when handling the litter box, feces, urine, or vomit of treated cats and wash hands with soap and water after every administration.
• Keep Away from Children: Methimazole is a known human teratogen; keep both the tablets and waste from treated cats completely out of reach of children.

Possible Side Effects

• Anorexia and Vomiting: Loss of appetite and vomiting are the most commonly reported reactions; let your vet know if these persist or get worse.
• Head and Facial Itching: Scratching around the head, face, and neck is a commonly reported skin reaction in cats on this medication.
• Lethargy and Depression: Some cats become less active or seem low in mood; keep an eye on energy levels during the first few weeks of treatment.
• Elevated Liver Enzymes: Liver enzyme rises and liver damage have been reported; regular bloodwork helps catch these changes before they become serious.
• Blood Disorders: Anemia, low platelet counts, and agranulocytosis have been reported; stop treatment and contact your vet right away if any of these are suspected.
• Serious Adverse Events: In some cases, serious adverse reactions have resulted in death or euthanasia; stop therapy and seek urgent veterinary care if severe signs develop.

Storage Information

• Room Temperature Storage: Store at room temperature, around 25°C (77°F), away from moisture and direct sunlight.
• Keep Container Tightly Closed: Always keep the bottle firmly closed to protect the tablets from moisture.
• Keep Away from Children: Store this prescription medication in a secure spot that children and other animals cannot get to.

Shipping & Return

We offer ground, express, and priority delivery; see our shipping policy for details.

For return instructions or product concerns, please refer to our detailed refund policy.

Prescription items are NON-RETURNABLE and NON-REFUNDABLE.

Frequently Asked Questions

Q1: What does Felimazole (Methimazole) 5 mg treat in cats?

Ans: Felimazole treats feline hyperthyroidism, an overactive thyroid condition that throws a cat's metabolism into overdrive and affects nearly every organ system in the body. It is the most common endocrine disease in middle-aged and older cats in the United States, affecting up to 10% of cats over the age of 10.

Q2: How does methimazole in Felimazole work to control hyperthyroidism?

Ans: Methimazole blocks thyroid peroxidase, the enzyme that incorporates iodine into thyroglobulin to produce T3 and T4 hormones. By shutting down this step, it reduces how much thyroid hormone the body makes and brings circulating levels back into a healthy range. Peak blood levels are reached within 1 to 1.5 hours after dosing.

Q3: How does the 5 mg Felimazole tablet differ from the 2.5 mg tablet?

Ans: Both strengths contain the same active ingredient and work the same way. Treatment always starts at 2.5 mg twice daily. The 5 mg tablet is used when doses need to go higher, since all adjustments are made in 2.5 mg steps. Your veterinarian will decide which strength fits your cat's T4 levels and clinical progress.

Q4: Why does my cat need regular blood tests while on Felimazole?

Ans: Methimazole can cause serious effects including blood disorders and liver enzyme changes that may not show obvious symptoms early on. Checking bloodwork at 3 weeks, 6 weeks, and every 3 months after that keeps thyroid levels on track and helps catch any concerning changes before they become harder to manage.

Q5: Is Felimazole a permanent cure for hyperthyroidism in cats?

Ans: No. Felimazole controls the condition by reducing hormone production but does not fix the underlying thyroid problem. If treatment stops, hormone levels rise again and symptoms return. Most cats stay on methimazole for life unless a definitive option like radioactive iodine or surgery is chosen.

Clinical Research

https://www.petmd.com/pet-medication/methimazole-tapazole-felimazole

https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/857