Health Issues Predators & Pests

Ivermectin For Parasite Control

I will preface this article by saying although I am not a veterinarian, I have done some research and consulted trained veterinarians before writing this piece. Feel free to do your own research and if you choose to use Ivermectin you’ll find recommended dosage guidelines below.

I know there is a lot of confusion about using Ivermectin for chickens and that’s because it would be used off-label, meaning that, although it is effective when treating chickens it was not developed for them. There is no scientific data about how it might affect them differently than mammals, the best route of administration and withdrawal periods for eating eggs or meat.

I asked an Avian Veterinarian about correct dosages for chickens and when I mentioned 3 drops for a standard sized bird, was told that was too much. They could not give me the correct dosage because it would be used off label, but pointed me in the right direction to make the calculation myself. They also gave me some info about how it works.

What is Ivermectin?

Ivermectin (Noromectin) is a broad spectrum anti-parasitic used to eradicate internal and external parasites in livestock, typically cattle and pigs. It can be administered via injection, orally or topically, is available in different strengths (i.e. 1mg, 5mg or 10mg) and dosages.

Parasitic Worms IN Chickens

Piperazine, which is only used on roundworms, paralyses the worms so they are expelled live from the chicken. Ivermectin, which can be used for internal worms, lice and mites (including scaly leg mites) kills them inside the body. In the process of dying they go through a period of hyperactivity and mass together in a ball. The downside of this is that if you use a lot of Ivermectin there may be complications when they are expelled.

Gape worms can be coughed up and potentially aspirated and intestinal worms will have to be excreted en masse. Ivermectin works, but you must be careful about not overdosing your birds, which can create a mass die-off of worms. You’d think that would be our aim, but chickens often live with internal parasites with no issues. It’s when there is a heavy infestation that it becomes problematic.

gape worm
Gapeworms in Necropsy Photo

Dosage Calculations & Treatment

Ivermectin Pour On, which is applied topically on the skin, has a universal recommended dosage of 200 micrograms/kilo. There are 1000 micrograms in 1 milligram and 5000 micrograms in 1 millilitre of liquid. 5000 mcgm divided by 200 mcgm = .04ml. Therefore the dosage would be .04 ml/kilo. One drop from a standard eyedropper = .05. So if your bird weighs 2 kilos the dosage would be just less than 2 drops! Believe me, it’s not always easy to be accurate and not use too much.

From my calculations, many people are giving too much and at too high a strength.

The dosages are based on 5mg of Ivermectin/1 ml solution. If you are using 10mg/1 ml you would have to reduce the amount used from 1-2 drops to 1 drop maximum. It is important to use a medication the way it was intended to be given – so don’t apply Ivermectin injectable or oral, topically (on skin).

The easiest way to treat them is to go out to your coop at night wearing a head lamp. You can either treat birds while they are sleeping on the roost bars or gently lift them off. Spread the feathers on their neck or between their shoulder blades and apply the drops directly on their skin.

One person can treat a number of birds in a few minutes. I work systematically (sometimes writing down the names of the birds I’ve done or working from one side of the coop to the other) to make sure everyone is treated at the same time and no one got missed. Treat new birds entering your flock and outgoing birds before they go off to a new home.

It’s important to repeat with a second treatment in 7-10 days to make sure you have killed any larvae that have hatched subsequent to the first one.

I see lots of folks offering advice about the use of Ivermectin in chickens on Facebook groups. Since Ivermectin is off-label, and untested, on chickens there are no consistent guidelines on a withdrawal period for eating eggs or meat.

You might not know that Ivermectin is used orally in people to treat roundworms, scabies and lice and has been called the ‘wonder drug‘ for its ability to treat River Blindness and other debilitating diseases in developing countries. The amount that a chicken absorbs in 1-2 drops is very small and probably poses a minimal risk. I was advised that if used, you could choose to eat your own eggs or poultry, but should withdraw those for sale to the public. Again, there is no ‘safe’ period that has been studied, but most chicken wormers recommend a 7-14 day withdrawal.

I would suggest that you not use Ivermectin until birds are fully developed and not more than twice a year. It’s good practice to rotate medications so that parasites don’t develop a tolerance to them. If you just want to treat for roundworms (which are carried by wild birds and earthworms), then you can use Piperazine/Wazine.

Roundworms Expelled In Chicken Poop

There are no drugs made for tapeworms in chickens. If you are treating that species you will need to find an off-label medication that is targeted toward them. Typically people opt for a product developed for cats. Speak to your vet about the most appropriate product to be used in chickens.

Tapeworms In Chicken Poop

I hope this is helpful.

Here are posts on different internal and external parasites: scaly leg mites, northern fowl & red mites, liceroundworms, gapeworm and tapeworms.



9 comments on “Ivermectin For Parasite Control

  1. Great research and a VERY good help to me THANX

    Liked by 1 person

  2. kittyxo101

    This was very helpful thank you so much. I have just purchased some for my flock. Seems a heap easier than the wormer I was using. Xx

    Liked by 1 person

  3. Hi just wondering if this ivermectin works to kill stick fast fleas as the attach themselves to the chicken

    Liked by 1 person

    • We don’t have stick tight fleas in this area, but Ivermectin is designed as a broad-spectrum insecticide aimed at killing both internal and external parasites, including those that suck blood. I can’t see why it wouldn’t work.


  4. Leonie Young

    What a fantastic article I have been reading lots of information on this but was not comfortable with any of them, The information was so inconsistent. Now I feel comfortable using ivermectin
    Thank you so much.

    Liked by 1 person

  5. Thank you so much for this article, I have purchased the Noromectin pour on as the above photo. I have Pekin Bantams so would 1 drop be enough given their smaller size?

    Liked by 1 person

  6. Thanks for such a clear summary! I’m a bit math challenged here so want to confirm before wildly over medicating everyone. I have a range of sizes but most of my chickens are on he hefty side, with my biggest hens being ~4.5kg and some roosters nearing 5.4kg. Is 3-4 drops correct for these chunky chooks?

    Liked by 1 person

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