Terbinafine - Oral

By Rania Gollakner, BS, DVM, MPH

What is terbinafine?

Terbinafine (brand name Lamisil®) is an oral systemic antifungal used primarily to treat skin fungal infections but is also used to treat systemic fungal infections.

Its use in cats and dogs to treat fungal infections is ‘off label’ or ‘extra-label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is terbinafine given?

Terbinafine is given orally (by mouth) in the form of tablets or granules. This medication should be given with food, especially if vomiting is a problem. The granule form should be mixed with soft food.

This medication can take a few weeks before full effects are noted, but gradual improvements are usually noticeable after a few days.

What if I miss giving my pet the medication or my shipment is late?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

This short acting medication is generally well-tolerated but studies in veterinary patients are limited. Gastrointestinal effects such as vomiting, lack of appetite, and diarrhea are possible. Other side effects include excessive panting and elevated liver enzymes. In cats, lethargy and facial itchiness has been reported.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Terbinafine should not be used in pets hypersensitive to it. Pets with active or chronic liver disease or with decreased kidney function should not use this medication. If it must be used, a lower dose should be considered. Use in breeding and pregnant pets has not been determined and should be used with caution. This medication should not be used in lactating pets.

Are there any drug interactions I should be aware of?

The following drugs should be used with caution when given with terbinafine: cimetidine, cyclosporine, fluconazole, rifampin, beta-blockers, doxorubicin, MAO inhibitors, SSRI's, and tricyclic antidepressants.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Pets taking this medication should have a baseline liver panel prior to starting the medication. If treating with this medication long-term, your veterinarian will perform periodic blood tests to check liver function and monitor for any changes or elevations.

How do I store terbinafine?

Terbinafine tablets and granules should be stored at room temperature, 25°C (77°F) in a tight container, away from moisture and light.

What should I do in case of emergency?

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.

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