Ivermectin for Chickens: Dosage, Benefits and Risks

Have you noticed that your chickens are looking somewhat itchy nowadays? Are their feathers ruffled for no particular reason? You might be dealing with annoying lice and mites in your backyard flock. These are often transmitted when your chickens are in contact with parts touched by wild-infected birds or rodents.

If you notice foamy-looking diarrhea among your backyard flock, this might be a sign of worm infestation. Worm infestation generally follows poor feeding habits. Either your bird has eaten the infected droppings of another bird, or the insect it ingests has worm eggs that will hatch in the chicken’s intestines.

Though healthy chickens can tolerate some worms, the birds can get stressed or sick when their worm loads overwhelm their immune systems.

Ivermectin is the drug of choice for managing worm, lice, and mite infestation in chickens. Read on to learn more about this crucial drug for your poultry keeping.

Understanding Parasites in Chickens

Parasites are tiny creatures living in or on a host’s body. They confer no benefit to the host but can be quite detrimental to its health. Chickens can become reluctant hosts to several parasites, so regular health checks are essential to keep your flocks healthy and detect the parasites early. The common parasites that affect chickens are ticks, flies, mites, bedbugs, worms, fleas, and lice.

Parasites in chickens can lead to weight loss, anemia, poor egg quality, abnormal droppings, reduced egg laying, poor appetite, excessive preening, missing/broken feathers, and in a few severe cases, death. As such, prompt treatment and prevention are crucial when dealing with parasites in chickens.

What Is Ivermectin?

Ivermectin is a lipid-soluble antihelminthic and antiparasitic agent that treats external and internal parasites. The drug is an avermectin. This is a group of naturally-occurring medications. Ivermectin is a product of the fermentation of Streptomyces avermitillis, which is an actinomycete that is isolated from soil.

The drug interferes with the muscle’s and nerve’s electrical impulses in a parasite to cause paralysis of the neuromuscular system. This happens by amplifying the effects of glutamate on the cell wall to allow the inflow of more chloride ions. This leads to cell wall hyperpolarization and paralysis, then death.

Several studies show that ivermectin is 90-95% effective against adult and immature parasites. Ivermectin is sold under several brand names, including Ivergot, Acarexx, Noromectin, Ivomec, and Imectin.

Benefits of Ivermectin for Chickens

In humans, ivermectin is used to manage topical and internal parasites. A few people have also used it off-label to manage coronavirus symptoms. The drug is used off-label for managing parasitic and other infections in chickens. Below are the common conditions in which the drug is indicated.

  • Mite infestation. The typical signs of mite infestation in chickens include listlessness, appetite changes, a pale comb, bald spots, scabs on the skin, ragged feathers, and feather pulling. You might also notice nits or crawling bugs on your chicken’s feathers. The most common mites for attacking chickens are red roost and northern fowl mites. They are eight-legged creatures that can be reddish, dark brown, or grey, often seen under roosts or along feather shafts at night.
  • Lice. These are six-legged, flat, round-headed insects that lie on the feather shafts and skin of your chickens. They are straw-colored or beige and feed on debris like feather quill casings and dead skin. You can confirm a lice infestation with nits and debris on the feather shafts.
  • Worms. Chickens can get a worm infestation when they eat excess worms or the droppings of an infected bird. The common worms that can affect chickens include roundworms, gapeworms, caecal worms, and capillary worms. You might notice these worms in eggs, droppings, and vomit. Though tapeworms are common in chickens, ivermectin is not so effective in treating tapeworm infestation.
  • Lesser mealworm: This is also called Aplhitobius diaperinus. It is a larva that acts as a reservoir and vector for several parasites and pathogens that affect poultry. Ivermectin can effectively control and eliminate this larva.

Use and Dosage of Ivermectin in Chickens

Ivermectin is commercially available as an intramuscular, intravenous, oral, subcutaneous, or topical preparation for horses, cattle, swine, goats, cats, dogs, and birds. The drug is often used in topical and oral forms in chickens. You can add it directly to your birds’ feeds and water to ease its uptake. In a few cases, the vet might recommend an intramuscular or subcutaneous injection of ivermectin for your chicken.

The dosage of ivermectin for your chickens will depend on its route of administration:

  • Topical: 0.4mg/kg
  • Oral: 0.04mg/kg
  • Intramuscular or subcutaneous: 0.02mg/kg

Ivermectin is given in two doses that are 10-14 days apart. While the first dose of ivermectin kills the parasite, the second dose kills the larvae which might have hatched after the first dose and gets rid of any residue from dead parasites. You should keep track of when you have administered ivermectin to avoid overdosing your chickens.

Ivermectin will work in 2-3 days, but the time it takes to do its job depends on the administration method. The injection is the fastest. You will detect ivermectin in your chicken’s blood about fifteen minutes after oral administration. The drug reaches its peak concentration after about 30-60 minutes and slowly declines after an hour.

Within 2-3 hours, ivermectin will have reduced by two times. It is rapidly excreted from a bird’s circulation after 12-24 hours. Nonetheless, it can accumulate in some tissues and organs because it is lipophilic. This accumulation causes a prolonged antiparasitic effect.

For topical applications, you can use an eyedropper to administer ivermectin. The number of drops for your bird will depend on the solution’s concentration. For example, if your medicine contains 5mg/ml of ivermectin, use one drop for every 2.5 pounds of chicken. Remember that most of these doses are in micrograms rather than milligrams.

Precautions and Potential Side Effects

When administering ivermectin, wear gloves and wash your hands afterward with soap and water to avoid contaminating your food and other surfaces. Ivermectin is safe for your chicken. However, it might have the following side effects:

  • Blindness
  • Diarrhea
  • Abdominal swelling
  • Ataxia

In general, you should not consume any animal products immediately after administering medications. However, withdrawal times are only recommended for a few drugs for chickens. You should not eat the skin/fat and liver of chickens after administering ivermectin for 8-12 days.

The kidneys and muscles require a withdrawal period of 0-10 days. Studies have also found traces of ivermectin in egg yolks. As such, withdrawing from consuming eggs for 2-7 days is advisable.

Ivermectin Alternatives for Chickens

Ivermectin should not be concurrently used with clotrimazole, fluconazole, doxycycline, erythromycin, St.John wort, itraconazole, and pentobarbital. Thankfully, a vet can recommend ivermectin alternatives if your chickens are taking these drugs or are allergic to ivermectin. These include fenbendazole, piperazine, levamisole and albendazole.

If you want a natural option for managing chicken parasites, you can opt for butter tree, negro-coffee, cashew nut, garlic, neem tree, betel pepper, and aloe vera are effective for roundworms. For external parasites like lice and mites, lined oil, petroleum jelly, permethrins, and pyrethrums are good alternatives to ivermectin.


Despite your best efforts at protecting chickens from parasites, they can sometimes infest your flock. In this case, prompt treatment with ivermectin is essential. This is an antihelminthic and antiparasitic agent that kills parasites by interfering with the conduction of nerve and muscle impulses to cause paralysis.

Ivermectin is effective against lice, mites, roundworms, capillary warms, cecal worms, lesser mealworms, and gapeworms. The drug is often administered topically and orally in chickens, with its dosage depending on your chicken’s weight and route of administration. It kills parasites within 2-3 days and is excreted within 12-24 hours.

Though safe, ivermectin can cause diarrhea, abdominal swelling, and ataxia. You can use febendaole, albendazole and piperazine in place of ivermectin. If you are looking for a natural alternative to ivermectin, pyrethrum, neem tree, aloe vera, and garlic will do.

avatar James
Hey, I'm James, a hardworking homesteader for more than 30 years. I enjoy the feeling of accomplishment that comes from tending my flock. I've raised chickens and ducks for eggs and meat for many years. I also have experience with other poultry too. Learn more

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