Amphotericin B for Birds: Uses, Aspergillosis Treatment & 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.

Amphotericin B is a prescription polyene antifungal medication used by avian veterinarians to treat serious fungal infections. It works by binding to ergosterol in the fungal cell membrane, which damages the fungus and helps stop it from spreading. In birds, it is most often discussed as part of treatment for aspergillosis, a fungal disease that commonly affects the respiratory tract and air sacs.

This medication is not something pet parents should give at home without a plan from your vet. In birds, amphotericin B may be used by intravenous infusion, intratracheal administration, or nebulization, depending on where the infection is located and how sick the bird is. The route matters because it changes both how well the drug reaches the infection and how likely side effects are.

Amphotericin B can be very helpful in the right case, but it also has a narrow safety margin when given systemically. That is why your vet may pair it with imaging, bloodwork, repeat exams, and sometimes other antifungal drugs. For many birds, amphotericin B is one part of a broader treatment plan that also addresses oxygen support, nutrition, husbandry, and the underlying reason the bird became vulnerable to fungal disease.

In pet birds, amphotericin B is used most often for aspergillosis, especially when the infection involves the air sacs, lungs, syrinx, or trachea. Aspergillosis is caused by Aspergillus species, most commonly A. fumigatus, and tends to affect birds that are stressed, immunocompromised, malnourished, exposed to moldy bedding or feed, or already dealing with another illness.

Your vet may consider amphotericin B when a bird has signs such as increased breathing effort, tail bobbing, voice change, exercise intolerance, weight loss, or severe respiratory distress. It may be used alone in some situations, but many avian vets combine local therapy like nebulization or intratracheal treatment with a systemic antifungal such as itraconazole or voriconazole, depending on the species and the extent of disease.

Amphotericin B may also be used in selected cases of Candida infection, especially for topical or local treatment of oral or cutaneous lesions, though other antifungals are often chosen first for routine yeast problems. The exact choice depends on the bird species, where the fungus is growing, how advanced the disease is, and what your vet finds on testing such as radiographs, endoscopy, cytology, culture, or PCR.

Do not dose this medication without your vet. Amphotericin B dosing in birds varies by route, formulation, and the bird's condition. Merck Veterinary Manual lists avian dosing examples including 1.5 mg/kg IV every 8 hours for 3-5 days, 1 mg/kg nebulized over 15 minutes every 24 hours for 10-14 days, and respiratory therapy references of 1 mg/mL solution nebulized for 15 minutes every 6-12 hours or 1 mg/kg intratracheally every 8-12 hours. These are reference ranges, not home-use instructions.

In real practice, your vet may adjust the plan based on species, body weight, hydration status, kidney values, and whether the infection is localized or invasive. A macaw with severe air sac disease may need a different approach than a cockatiel with early upper airway involvement. Some birds need hospitalization for IV treatment, oxygen support, and careful fluid therapy.

Monitoring is a major part of safe dosing. Birds receiving systemic amphotericin B often need baseline and repeat bloodwork, with close attention to kidney function, hydration, packed cell volume, and electrolytes. If your bird is on nebulized therapy, your vet may also recheck breathing effort, weight trend, appetite, and follow-up imaging or endoscopy to see whether the plaques or granulomas are improving.

If you miss a treatment or your bird seems more tired, stops eating, or breathes harder after a dose, contact your vet promptly. Do not double the next dose unless your vet specifically tells you to.

The most important risk with amphotericin B is kidney injury, especially with systemic IV use. Merck notes that nephrotoxicity is the primary toxicity of amphotericin B, and renal monitoring is a routine part of treatment. In birds, this may show up as worsening weakness, dehydration, reduced appetite, abnormal droppings, or lab changes before obvious symptoms appear.

Other possible side effects include anorexia, nausea-like behavior, vomiting or regurgitation in species that can show it, drug fever, hypersensitivity reactions, anemia, cardiac rhythm changes, liver dysfunction, and neurologic signs. IV administration can also cause infusion reactions, and leakage outside the vein may irritate tissues. Nebulized treatment is often used to reduce whole-body exposure, but some birds may still become stressed by handling or aerosol sessions.

See your vet immediately if your bird has open-mouth breathing, collapse, severe weakness, marked decrease in droppings, sudden swelling, worsening respiratory distress, or stops eating. Birds can hide illness until they are very sick, so even subtle changes during antifungal treatment matter.

Because side effects can overlap with the fungal disease itself, your vet may recommend repeat exams rather than waiting to see if things improve on their own. Early adjustments can make treatment safer and more sustainable.

Amphotericin B has several important drug interactions, mainly because it can stress the kidneys and affect electrolytes. Merck advises caution or avoidance with aminoglycoside antibiotics because the combination can increase nephrotoxicity. That matters in birds, since aminoglycosides may also be used in some respiratory or gram-negative infections.

Other interactions reported in veterinary references include increased risk with cyclosporine and other potentially kidney-damaging drugs, plus added concerns with thiazide diuretics or mineralocorticoids because they can worsen hypokalemia. Merck also lists interactions with digitalis drugs, curarizing agents, and some antineoplastic drugs.

If your bird is taking more than one medication, tell your vet about all prescriptions, compounded drugs, nebulized medications, supplements, and over-the-counter products. That includes anything added to water or food. Your vet may change the schedule, choose a different antifungal, or increase lab monitoring to lower the risk of complications.

Do not start or stop another medication during amphotericin B treatment unless your vet says it is safe. In birds with fungal disease, even small changes in hydration, kidney function, or respiratory status can affect the treatment plan.