Coccidiosis in Chickens

Do you have sick baby chicks at home? If so, you may want to keep reading.  Coccidiosis is the most common problem that causes sick baby chicks.  It can also affect adult chickens.

👉Speaking of chickens, if you want to really spoil your chickens, you'll want to get your hands on our FREE Homemade Chicken Recipes Guide. It's a collection of 25 recipes for homemade feed, treats herbal blends and more for your flock! Grab yours here!

Have you been to the feed store to buy chick feed and noticed that a vast majority of the chick feed offered is 'medicated'?  What is medicated chick feed for?  It's a common misconception that 'medicated' feed means feed that is filled with antibiotics.

Medicated feed is designed to keep coccidiosis at bay; not prevent chicks from getting bacterial infections (which is what antibiotics do).

​What is coccidiosis and why is there so much medicated feed out there to prevent it?  Is it really that big of a problem?

What is coccidiosis in chickens?

Coccidiosis is a very common disease in chickens that can be deadly, especially in younger birds. In fact, it's the most common cause of death on broiler farms.  Broiler farms raise millions of chickens per year in the U.S.

Coccidiosis is a digestive disease.  The parasite that causes the disease is the microorganism coccidia.  Coccidia affects many animals other than poultry.  It can affect other livestock also, including goats, horses, dogs, and cats.

Coccidia is very common and can cause issues, even when you take all of the precautions to avoid it.

​In chickens, coccidiosis is caused by the protozoan parasite Eimeria.  There are nine different types of coccidia that can affect chickens. Most of them will affect the digestive tract, but some can attack other organs.

Life Cycle of Coccidia

The coccidia parasite relies on a host organism, in this case, the chicken, to reproduce and survive.  Understanding the life cycle of coccidia is important; being able to break the life cycle is key to keeping your chickens healthy.

sick baby chicks, what is coccidiosis in chickens

Birds get infected with coccidia when they consume water or contaminated feed that contains the eggs of coccidia.  The eggs of coccidia are called oocysts.

The oocysts are found in feces and can come from infected or wild birds. A healthy bird ingests some of the oocysts and becomes infected. Once the eggs are in the bird, they work their way down the bird's digestive tract.

In the digestive tract, the eggs start to reproduce within 48 hours.  The coccidia release more eggs, which move through the chicken's digestive tract and are released back into the environment with feces.

The oocysts now wait in the environment for another bird to consume them and start the life cycle over.

Coccidia can survive longer in the environment when temperatures are warm and the environment is moist. Because of this, infections are most common in the spring and summer months.  Coccidia cannot survive long in cold or dry conditions, so infections in fall and winter are much lower.

​For more information about how coccidia can spread, watch the video below:  (Note: the video is intended for farmers raising flocks of broiler birds, but the same principles apply to people raising backyard chicken flocks.)

What does coccidia do in the chicken?

Coccidia usually lives in the digestive tract of the chicken.  In small numbers, they aren't harmful.  In fact, most adult chickens have had coccidiosis and have built a natural immunity to it.

However, when chickens are infected and have large numbers of coccidia in the digestive tract, problems will occur.

The coccidia can damage the lining of the digestive tract. Coccidiosis can interfere with how well your chicken can absorb nutrients or water. Coccidia can also damage the lining of the digestive tract enough to cause internal bleeding and anemia.

A chicken that is sick with coccidia is much more likely to fall ill with another illness. The stress of having coccidiosis can lower the chicken's immune system, making them susceptible to other health problems.

Coccidia is most likely to cause problems in younger chickens that have not built a natural immunity yet.  Although it can affect older chickens and make them sick, it's not as likely to do so.

​When chickens are gradually exposed to strains of coccidiosis, their body learns how to defend against the parasite on its own. Chickens that are under stress (i.e. being introduced to a new flock or being relocated), have another disease or illness, or are being exposed to a new strain of coccidia can develop a more advanced case of coccidiosis.

Signs and Symptoms of Coccidiosis

Chickens that have a slight case of coccidiosis may not show many, if any signs, of being ill.  Chickens are prey animals and are very good at hiding when they don't feel well.  Remember, in nature, prey animals that are sick or wounded are often targeted by predators.  Because of this, your chickens will not show signs that they are sick until they are pretty sick.

With that being said, if you know your chickens well, you might pick up on some slight clues that your chicken doesn't feel good.

A more severe case of coccidiosis will have some signs that you can spot easily.

One of the first things that you'll notice is your chicken will stop eating or drinking.  Coccidia affects the digestive tract and can make eating or drinking uncomfortable.  Not eating or drinking are one of the first signs that your chicken doesn't feel well for many different reasons.

​As the infection gets worse, the signs become more clear.  You'll notice your chicken standing with a hunched appearance, with his/her head down by the shoulders and feathers ruffled. The comb and wattles may turn pale due to anemia.

sick baby chicks, what is coccidiosis in chickens

The feces will have mucus in it or blood.  The feces may look runny or not the right color.

Young birds that are still growing will have slowed growth rates.  This is likely due to a combination of going off feed and limited nutrient absorption reducing the number of nutrients that the growing chicks have to use to grow.

Chickens that are older and not actively growing may lose weight.  Prolonged illness can cause laying hens to stop laying.

Coccidiosis is quickly spread within a flock.  You'll likely notice that multiple birds in your flock don't feel well and are coming down with similar symptoms.

Common signs of coccidiosis:

-reduced feed consumption
-reduced drinking
-lethargic or staying away from other chickens
-slow growth (in growing chickens)
-weight loss (older chickens)
-hunched stance
-ruffled feathers
-possible pale wattles and comb (anemia)
-diarrhea that is mucousy, runny, or bloody
-can lead to death


​The only way to be certain that you're dealing with a coccidia problem is to have your veterinarian do a fecal test.  This is a very quick and cheap test for your vet to perform.  There are other diseases that cause similar signs and require different treatments.  Testing is key to making sure that you're treating the correct problem.

How to Treat Coccidiosis in Chickens

Coccidiosis is one of the most common and deadly diseases that affect chickens.  It's a naturally occurring problem that is made worse by the way that we keep chickens today (more on this below). This post contains affiliate links. To view my affiliate disclaimer, click here.

​Chickens that have a coccidiosis infection need to be treated with a medication called a coccidiostat.  A common example of this is Corid.  The active ingredient in Corid is amprolium.  Amprolium is a powerful medication that can knock out a coccidiosis infection quickly.

Corid comes in either a powder or a liquid.  Both forms are added to the drinking water.  One isn't more effective than the other; they will both get rid of a coccidiosis infection in your chickens.

To treat coccidiosis with Corid, remove all drinking water from the run and coop.  Wash out the waterers well, using soap and warm water to clean the entire waterer, inside and out.  Once the waterer is clean, fill it up with fresh water.

Here are the Corid dosages to use:

-Liquid Corid: 9.5 cc per gallon of water
-Powdered Corid 20%: 1/2 tsp per gallon of water


Both forms should be mixed well into the water.  The medicated water should be the only source of drinking water available for 5 days.  Make sure that chickens have access to the medicated water for 5 days to eliminate all coccidia.

You can treat coccidia with another coccidiostat, Toltrazuril.  It is harder to find though and cannot be fed with B vitamins.  B vitamins cause it to become ineffective.  For this reason, I've found it easier to use Corid to treat coccidiosis.

If you do use toltrazuril to treat chickens, most vets recommend using this dosage: 6 mg/kg added to drinking water for 2 days.

Chickens that are infected with coccidiosis will have a weakened immune system.  To prevent additional illnesses from occurring at the same time, most veterinarians will recommend giving the chickens an antibiotic along with a coccidiostat to keep them from getting a secondary infection.

Supporting the good bacteria in the digestive tract with probiotics will also help.  When the digestive tract is filled with beneficial bacteria, the harmful microorganisms, like coccidia, cannot survive. A probiotic supplement can help support a healthy microorganism population.

After you've treated your chickens with either Corid or toltrazuril, be sure to replenish the vitamins in their body.  Both treatments can affect the chicken's ability to absorb B vitamins.  Use a product like Poultry Nutridrench to provide them with vitamins.

How to Treat Coccidiosis in Chickens Naturally

Coccidiosis can quickly become life-threatening for chickens.  It's important to realize that many natural remedies may not be effective enough to treat your chickens.  Some of the 'natural' remedies that I've seen include vinegar, yogurt, and garlic.

Vinegar is thought to work because it creates an acidic environment in the digestive tract.  This won't be enough to get rid of a coccidiosis problem.

Yogurt is thought to work because it introduces beneficial bacteria to the digestive tract.  Again, this won't be enough because the coccidia already exists in large numbers, so they will probably out-compete the good bacteria in the yogurt.

Garlic can help prevent a coccidiosis problem from happening, but it's not effective enough to handle a coccidiosis infection once it's taken hold.

​Instead, use these natural methods to help support your chicken's health and to prevent your chickens from getting sick.  Don't rely on these methods to treat your chickens.  Instead, run to your local farm supply store and pick up a bottle or package of Corid.

Can a chicken survive coccidiosis without treatment?

Yes, as long as the infection isn't too severe.  Chickens that are gradually introduced to coccidiosis naturally will likely not get sick or show signs of an illness because their body learns how to deal with it gradually.

​A severe case of coccidiosis can be life-threatening.  It's also very contagious, meaning it can take out a large number of your chickens rapidly.  It's best to treat the entire flock if you have a few chickens showing signs of illness.

Can chickens recover from coccidiosis on their own?

Again, this depends on the level of infection.  Most adult chickens have built a natural immunity to coccidiosis. A chicken with a severe case of coccidiosis may or may not recover on its own.  It's best to treat all chickens in the flock by replacing the drinking water with medicated water for 5 days.

Preventing Coccidiosis in Chickens

Preventing coccidiosis in chickens can be done by increasing biosecurity, improving sanitary conditions, and providing immunity to your chickens.

Using Biosecurity to Prevent Coccidiosis

Biosecurity is a term that is used to describe everything that you can do to reduce disease transmission.  This involves quarantining new flock members and taking extra precautions to prevent the spreading of disease.

Remember when I said that most adult chickens have a natural immunity to coccidiosis?  That's because they've been gradually introduced to coccidia.  There are several strains of coccidia that can affect chickens.  This doesn't mean that they've been introduced to all strains of coccidia, just the ones that will likely affect them within your flock.

So, let's say that you bring home a new rooster.  He's grown and very healthy.  You immediately put him in with your hens to get him acquainted with his new flock.  A couple of days later, you notice that all of your chickens are acting off, except for your new rooster.  What happened?

It's possible that the new rooster had a natural immunity to a type of coccidia that your flock had never been introduced to before.  Since adult chickens continue to shed oocysts from coccidia that they are immune to, the new strain of coccidia infected the coop and run.  Your other chickens come into contact with it and become sick. That's why they got sick and he didn't.

Quarantining chickens that are new can help to reduce disease. Coccidiosis isn't the only disease that can affect chickens.  It's always a good idea to keep new chickens separated from your existing flock for one month.  If they have a cold or some kind of illness, that will give them time to develop symptoms.  If they show signs of an illness while they are quarantining, treat them and make sure they are well and have completed treatment before introducing them to your flock.

You'll also want to avoid sharing poultry equipment with other chicken keepers. Even your next-door neighbor's chickens can have different immune systems than your chickens.  Avoid spreading coccidiosis by acting like all other chicken flocks have an illness that could make your chickens sick.

This includes taking precautions like:

-Avoid swapping poultry equipment with other owners.  Equipment that is swapped should be thoroughly cleaned and sanitized.
-Avoid handling other chickens and then handling yours without washing your hands.
​-Don't walk in someone else's coop and then coming home to walk in yours.  Coccidia oocysts can be on the ground and can get picked up by your shoes.

Improving Sanitary Conditions to Prevent Coccidiosis

Coccidia oocysts are transmitted through contaminated water, feed, and the environment.  A sanitary coop can reduce the number of oocysts that could make your chickens sick.

Always ensure that waterers are filled with clean, fresh water. Clean and sanitize waterers frequently.  This will not only remove coccidia that may be lurking in the water, but it can remove other harmful bacteria or microorganisms.

Look for a waterer that prevents chickens from roosting on it.  Waterers with a slanted or domed top are designed to keep chickens off of them.  When chickens roost on a waterer, they're likely to poop on it, getting feces (and potential oocysts) into the drinking water.

Make sure that chickens have plenty of room.  For average-sized chickens, this means at least 4 square feet of room in the coop and 10 square feet of room in the run, per chicken.  The more room that you can give them, the better.

Keep bedding clean and dry.  Remove wet, soiled bedding.  Warm and moist conditions are the best conditions for coccidia.  Cold and dry conditions will kill coccidia.  Wet, soiled bedding is the ideal environment for coccidia to spread in.

​Increase ventilation to help keep bedding dry.

sick baby chicks, what is coccidiosis in chickens

Also, remove soiled feed. Feed that has feces in it is contaminated and should be removed. Feeders that hold a large amount of feed but only allow a small amount exposed at a time are ideal.

​You can treat the floor of the run with diluted bleach or lime to reduce the coccidia on the ground.  Tilling the floor of the run can also help to reduce coccidia oocysts on the floor.

Providing Immunity to Chickens to Prevent Coccidiosis

When exposed to coccidia gradually, chickens will develop natural immunity.  If your coop and run are large enough, you can achieve natural immunity.  To do this, start introducing your younger birds to the space that older birds live for a few hours a day.

This will introduce them gradually to coccidia, helping them to develop a natural immunity to it.  It will also help to gradually introduce younger chickens to an existing flock.

For younger chickens that can't be exposed to older chickens, you can choose to have them vaccinated. Most reputable hatcheries will offer the option to get chicks vaccinated.  If your chicks have been vaccinated, you don't need to feed them medicated feed.

Chicks that have not been vaccinated can be fed medicated feed.  Do not use medicated feed with the vaccine.  This will not 'double' the effectiveness, but can actually make chickens more susceptible to infection.  Choose one option and stick with it.

​Offer chick probiotics. This will help to increase the number of good bacteria in the digestive tract, making it harder for bad bacteria and coccidia to live.

Can you eat eggs from a chicken with coccidiosis?

Yes. Corid treatments for coccidia will not harm the egg and there is no withdrawal period for eating eggs from chickens treated with amprolium.

​Chickens with more severe cases of coccidiosis may stop laying while they are sick.  Chickens that continue to lay will produce eggs that are safe to eat. The coccidia will not get into the eggs.

​If you haven't yet, grab your FREE copy of the Homemade Chicken Recipes guide and get instant access to 25 recipes for making homemade feed, treats, herbal blends and more that your flock will love!

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Have you had to treat chickens with coccidiosis? How did you know that your chicken had coccidiosis? Let me know below!

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Hey, I'm Shelby!

Founder of Garden. Farm. Thrive.

I'm a multigenerational homesteader, former high school and college agriculture teacher, and your guide for embracing a simpler, more traditional lifestyle. Come along as I teach you how to grow your best garden, raise chickens and other livestock, learn traditional skills and create the homesteading haven of your dreams.

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