Terbinafine for Macaws: Uses, Dosing & Side Effects

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Terbinafine is an allylamine antifungal. It works by disrupting fungal cell membrane production, which can help stop susceptible fungi from growing or kill them outright. In veterinary medicine, it is used extra-label, meaning it is a human medication that your vet may legally prescribe for animals when appropriate.

In macaws and other pet birds, terbinafine is most often discussed as part of treatment for fungal disease, especially when your vet is concerned about respiratory fungal infections such as aspergillosis. It may also be considered for some superficial fungal problems, depending on the organism involved and your bird’s overall condition.

Because birds metabolize medications differently than dogs and cats, dosing and monitoring need to be tailored carefully. Your vet may prescribe a tablet, compounded liquid, or another formulation that is easier and safer to give to a macaw.

In macaws, terbinafine is most commonly used as one option for fungal infections. A frequent reason your vet may discuss it is aspergillosis, a serious fungal disease that can affect the air sacs, lungs, and sometimes other organs. Macaws with fungal disease may show vague signs at first, such as reduced activity, weight loss, voice changes, tail bobbing, or increased breathing effort.

Terbinafine is not the only antifungal used in birds. Depending on the suspected fungus, your vet may recommend terbinafine alone, combine it with another antifungal, or choose a different medication entirely. That decision often depends on where the infection is located, how sick your bird is, imaging or endoscopy findings, and whether culture or cytology results are available.

For some birds, terbinafine is part of a longer treatment plan that also includes supportive care, environmental changes, nutritional support, and repeat rechecks. Fungal disease in parrots can take weeks to months to manage, so follow-up matters as much as the medication itself.

Published avian references list terbinafine at 10-15 mg/kg by mouth every 12 hours in pet birds. Merck also lists a 1 mg/mL solution for nebulization for 30 minutes in avian patients, but nebulized therapy should only be used if your vet specifically prescribes it and gives you exact preparation instructions. These are reference ranges, not a home dosing guide.

Macaws vary widely in body weight, liver function, hydration status, and severity of illness. Because of that, your vet may adjust the dose, route, or treatment length for your individual bird. A compounded liquid is often used so the dose can be measured more accurately for the bird in front of them.

Terbinafine is often given with food to reduce stomach upset. Do not crush, split, or reformulate tablets unless your vet or pharmacist tells you to. If you miss a dose, contact your vet for instructions rather than doubling the next dose.

Your vet may recommend baseline and follow-up bloodwork, especially for longer courses. That is important because antifungal treatment in birds can be prolonged, and monitoring helps your vet balance effectiveness with safety.

Many birds tolerate terbinafine reasonably well, but side effects can happen. The most commonly reported veterinary concerns with oral terbinafine are gastrointestinal upset, including decreased appetite, vomiting, or loose droppings. In a macaw, even a short period of poor appetite can become serious quickly.

Other concerns include lethargy, behavior changes, and possible liver irritation or elevated liver enzymes. In birds, pet parents may notice fluffed posture, less vocalizing, reduced interest in food, weakness, or worsening weight loss. These signs do not always mean the medication is the cause, but they do mean your bird should be checked.

See your vet immediately if your macaw has trouble breathing, repeated vomiting, marked weakness, collapse, severe anorexia, or suddenly worsened droppings while on terbinafine. Respiratory fungal disease itself can also worsen quickly, so it is safest not to wait and see.

If your bird is on terbinafine for more than a short course, ask your vet what monitoring plan they recommend. Recheck exams, weight checks, and bloodwork can help catch problems early.

Terbinafine can interact with other medications, especially drugs that are processed through the liver. In birds, this matters because antifungal treatment is often used alongside antibiotics, anti-inflammatory medications, nebulized therapies, pain control, or nutritional support.

The exact interaction risk in macaws is not as well studied as it is in dogs, cats, or people, so your vet will usually take a cautious approach. Be sure they know about every product your bird receives, including compounded medications, supplements, probiotics, herbal products, and over-the-counter items.

Particular caution is reasonable when terbinafine is combined with other drugs that may affect the liver or appetite. Your vet may also adjust treatment if your macaw has known liver disease, kidney disease, breeding status concerns, or a history of medication sensitivity.

Do not start or stop another medication during antifungal treatment without checking first. Even a well-meant change at home can make side effects harder to interpret or alter how your bird responds to therapy.