Amphotericin B for Chickens: 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.

Amphotericin B is a prescription antifungal medication used by your vet for serious fungal infections. In birds, it is most often discussed for aspergillosis, a fungal disease that can affect the lungs, air sacs, and sometimes other organs. It belongs to the polyene macrolide class and works by binding to fungal cell membranes, which damages the fungus and can stop it from growing.

In chickens, amphotericin B is not a routine backyard medication. It is usually reserved for cases where your vet suspects or confirms a significant fungal infection and decides that the potential benefits outweigh the risks. In avian medicine, the drug may be used by intravenous infusion, nebulization, or direct local administration to lesions, depending on the case and the bird's stability.

This medication needs careful handling because it can be hard on the kidneys and fluid balance. That is why treatment decisions usually involve a full exam, discussion of food-safety implications, and a plan for monitoring during therapy.

In chickens, amphotericin B is most commonly considered for aspergillosis, especially when disease involves the respiratory tract. Merck notes that aspergillosis occurs in poultry, including chickens and turkeys, and lesions can include fungal pneumonia and granulomatous disease in the lungs and air sacs. In avian practice more broadly, amphotericin B may be used when fungal disease is severe, localized, or not responding well enough to other options.

Your vet may consider amphotericin B as part of a larger treatment plan rather than as a stand-alone answer. That plan can include environmental correction, supportive care, oxygen or nebulization support, endoscopic evaluation, and sometimes other antifungal drugs. In some birds, local treatment directly into a lesion or air sac may be discussed for focal disease.

Because chickens are food-producing animals, use requires extra caution. If amphotericin B is used extra-label, your vet must establish an appropriate withdrawal interval for meat and eggs. That makes this a medication where diagnosis, recordkeeping, and follow-up matter as much as the drug itself.

Amphotericin B dosing in chickens should only be set by your vet. Published avian references list several routes used in birds, but the right choice depends on the suspected fungus, where the infection is located, whether the chicken is stable enough for handling, and whether the bird is kept for eggs or meat.

Merck's veterinary dosing table lists 1.5 mg/kg IV every 8 hours for 3 to 5 days in birds and 1 mg/kg by nebulization over 15 minutes every 24 hours for 10 to 14 days in birds. Other avian references describe local or lesion-directed use in selected cases. These are not at-home instructions. They are examples of published veterinary dosing ranges that still require case-by-case adjustment.

Your vet may also change the plan based on hydration status, kidney values, response to treatment, and whether another antifungal is being used at the same time. If a dose is missed or your chicken seems weaker after treatment, contact your vet before giving more medication.

The biggest concern with amphotericin B is kidney toxicity. This drug can also affect electrolytes, especially potassium, and may be harder on birds that are dehydrated or already medically fragile. That is one reason your vet may recommend fluids, repeat exams, or lab monitoring during treatment.

Possible side effects can include decreased appetite, lethargy, weakness, increased thirst, changes in droppings or urates, dehydration, and worsening condition after dosing. With nebulized or local respiratory treatment, some birds may show temporary stress with handling or respiratory irritation. Birds with advanced fungal disease may also decline because of the infection itself, not only because of the medication.

See your vet immediately if your chicken becomes markedly weak, stops eating, has labored breathing, collapses, or seems much worse after treatment. In birds, small changes can become serious quickly.

Amphotericin B should be used carefully with other medications that can stress the kidneys or shift electrolytes. In veterinary medicine, that includes concern with aminoglycoside antibiotics and other potentially nephrotoxic drugs. Dehydration can also increase risk, so your vet may adjust fluids and supportive care before or during treatment.

If your chicken is receiving diuretics, anti-inflammatory drugs, injectable antibiotics, or other antifungals, tell your vet before treatment starts. Even if a drug is commonly used in poultry, combining it with amphotericin B may change the safety profile.

There are also practical administration issues. Amphotericin B formulations are route-specific and must be prepared correctly by veterinary staff. Do not substitute human products, compounded products, or leftover medications without your vet's instructions.