Levamisole for Birds: How to Safely Treat Parasitic Infections in Poultry and Pet Birds

• By Ian Roddick
• 31 Oct, 2025
• 2 Comments

Parasites are a silent killer in bird flocks. Many bird owners, whether raising backyard chickens or caring for a beloved parrot, don’t realize their birds are infected until it’s too late. Weight loss, ruffled feathers, diarrhea, and sudden death can all be signs of a hidden worm infestation. Levamisole is one of the few safe, effective dewormers approved for use in birds-but only if used correctly. Wrong dosage, wrong timing, or using the wrong formulation can do more harm than good.

What is levamisole and how does it work in birds?

Levamisole is a synthetic anthelmintic, originally developed for livestock, that works by paralyzing parasitic worms. It targets nematodes-roundworms like Ascaridia galli in chickens or Capillaria in canaries and parrots. Once the worms are paralyzed, they lose their grip on the bird’s intestinal lining and are passed out in the droppings.

Unlike some older dewormers that kill worms slowly and cause toxic reactions, levamisole acts quickly and cleanly. It’s absorbed through the bird’s gut and enters the bloodstream, where it reaches the parasites. The drug doesn’t harm the bird’s cells, making it one of the safer options when dosed properly. It’s been used in poultry since the 1980s and is now common in avian veterinary practice for both commercial and pet birds.

Which birds can be treated with levamisole?

Levamisole is approved and effective for a wide range of birds, including:

• Chickens and other poultry (turkeys, ducks, geese)
• Parrots (African greys, cockatiels, budgies)
• Canaries and finches
• Pigeons and doves
• Exotic birds like toucans and hornbills

It’s not recommended for very young chicks under 2 weeks old or for birds under extreme stress, such as those recovering from surgery or severe illness. Always consult a vet before treating breeding hens or birds that are molting-these are high-risk periods where even safe drugs can cause complications.

Common parasitic infections in birds

Not all worms are the same. Different species affect different birds:

• Ascaridia galli - Large roundworms in chickens. Can grow up to 10 cm long. Causes blockages, poor growth, and sudden death.
• Capillaria spp. - Hairworms that live in the crop and intestines. Common in pet birds. Leads to weight loss and bloody droppings.
• Heterakis gallinarum - Small roundworms. Often found with coccidia. Can carry harmful protozoa.
• Strongyloides spp. - Threadworms in the lungs or intestines. Seen in pigeons and wild birds.

Signs of infection include: reduced appetite, dull plumage, diarrhea with mucus or blood, decreased egg production in hens, and birds sitting hunched with eyes closed. If you see worms in droppings, that’s a clear sign-but many infections show no visible worms at all. Fecal float tests from a vet are the only reliable way to confirm.

How to dose levamisole in birds

Levamisole is sold as a liquid concentrate (usually 10% or 15% solution) or as a powder. For birds, it’s almost always given in water, never as a tablet or injection unless directed by a vet.

The standard dose is 10 mg per kg of body weight. That means:

• A 1 kg chicken needs 10 mg of levamisole
• A 100 g budgie needs 1 mg
• A 2 kg turkey needs 20 mg

Most commercial levamisole solutions are 10% (100 mg/mL). So for a 1 kg bird, you’d need 0.1 mL of solution. That’s tiny-use a syringe without a needle to measure accurately.

Here’s how to mix it:

1. Calculate the total amount needed for all birds.
2. Dilute the levamisole in clean, chlorine-free water. Use a ratio of 1 mL of 10% solution per 1 liter of water for general flock treatment.
3. Offer this as the only water source for 24 hours. Remove all other water sources.
4. Do not mix with food or feed. Birds drink more than they eat, so water dosing ensures accurate intake.
5. After 24 hours, replace with fresh, clean water.

Never exceed the recommended dose. Overdosing can cause tremors, loss of coordination, or even death. If you’re unsure, start with half the dose and watch for reactions.

When to treat your birds

Timing matters. Don’t treat birds randomly. Here’s a practical schedule:

• Poultry flocks: Treat every 3 to 4 months. Spring and fall are best-before peak laying and before winter stress.
• Pet birds: Treat once a year, unless signs appear. Annual fecal checks are ideal.
• After introducing new birds: Always quarantine and deworm before mixing with your flock.
• After outbreaks: Treat the whole flock, even birds that look healthy.

Don’t treat during molting. Birds use all their energy to grow new feathers. Adding a drug can trigger feather loss or slow regrowth. Also avoid treating during extreme heat or cold-stress reduces drug effectiveness and increases risk of side effects.

What to expect after treatment

Within 24 to 48 hours, you’ll likely see dead worms in the droppings. They look like thin, white threads or small coils. This is normal. Don’t panic.

Some birds may seem lethargic for a day. That’s the body clearing the dead worms. If a bird stops eating, drinks excessively, or shows tremors, contact a vet immediately. These are signs of overdose or reaction.

Recovery is usually quick. Birds should return to normal activity and appetite within 3 days. Egg-laying hens may take a week to resume full production. That’s fine-it’s better than losing birds to worms.

Side effects and safety concerns

Levamisole is safe when used correctly, but it’s not risk-free.

• Overdose: Can cause neurological symptoms-head tilting, stumbling, seizures. Stop treatment and give activated charcoal if available.
• Allergic reactions: Rare, but some birds develop swelling or skin irritation. Discontinue use.
• Drug interactions: Do not use with other dewormers or antibiotics without vet advice. Some combinations can be toxic.
• Withdrawal period: For laying hens, wait 7 days after treatment before consuming eggs. For meat birds, wait 14 days before slaughter. Always check local regulations.

Never use human-grade levamisole. It may contain additives or fillers that are toxic to birds. Only use veterinary-grade products labeled for avian use.

Alternatives to levamisole

While levamisole is one of the best options, it’s not the only one:

• Flubendazole: Works well for Capillaria and Ascaridia. Given in feed. Safer for young birds.
• Ivermectin: Effective for mites and some worms, but risky in small birds. Can cause paralysis.
• Piperazine: Older drug, less effective now. Only works on roundworms, not hairworms.
• Natural remedies: Garlic, pumpkin seeds, diatomaceous earth-these may help prevent infestations but don’t kill established worms.

Levamisole remains the top choice for broad-spectrum worm control in birds because it’s reliable, fast-acting, and has a wide safety margin when dosed right.

Prevention is better than treatment

Once you’ve treated your birds, don’t let them get reinfected. Parasites come from:

• Contaminated soil or bedding
• Wild birds or rodents
• Dirty waterers and feeders
• Infected droppings

Prevention steps:

• Change bedding weekly. Remove droppings daily.
• Elevate feeders and waterers to prevent contamination.
• Limit access to wild birds-use covered runs.
• Disinfect coops with a poultry-safe cleaner like bleach solution (1:10).
• Rotate outdoor pens if possible. Let the ground rest for 30 days before reusing.

Good hygiene cuts worm transmission by over 80%. Combined with annual deworming, it keeps your birds healthy without constant drug use.

Frequently Asked Questions

Next steps and troubleshooting

If your birds still show signs of worms after treatment:

• Recheck the dose. Did you measure accurately? A 10% solution requires microliter precision.
• Confirm the parasite type. Some worms, like tapeworms, don’t respond to levamisole.
• Test droppings again. Maybe the infection is still active.
• Look for environmental causes. Is bedding damp? Are wild birds getting into the coop?

If a bird has a bad reaction-tremors, weakness, or breathing trouble-remove all water, isolate the bird, and contact a vet immediately. Keep a record of the dose, date, and symptoms. This helps the vet respond faster.

Keep a log: When you treated, what dose, how many birds, what symptoms before and after. Over time, you’ll see patterns. You’ll know when your flock needs treatment-and when it doesn’t.