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Health note: This guide is general information, not veterinary advice, and our writers are not veterinarians. If a bird is sick, injured or not improving, contact a poultry vet, and always follow product labels and your vet's instructions for any medication. How we write health content.
The worms that most often affect backyard chickens are large roundworms, cecal worms, capillary worms, gapeworms and tapeworms. A light worm burden often causes no signs, while heavy infections can cause weight loss, diarrhea, fewer eggs and, with gapeworms, gasping. The best way to know what your flock has is a fecal test from your vet or a state poultry lab.
Key Takeaways
- Main chicken worms: large roundworm, cecal worm, capillary worm, gapeworm and tapeworm.
- Tapeworms need an intermediate host such as insects, earthworms, slugs or snails.
- Worm eggs are shed on and off, so one clean fecal sample doesn’t prove there are no worms.
- Corid and Amprol treat coccidiosis, a protozoan disease; they are not dewormers.
Correction: an earlier version of this article described human worm infections (such as pinworms), included unfinished placeholder products, rated herbal remedies without evidence, and recommended coccidiosis medicines as dewormers. It has been rewritten.
The Main Types of Worms in Chickens
| Worm | Where it lives | What to know |
|---|---|---|
| Large roundworm (Ascaridia galli) | Small intestine | The most common worm in chickens; heavy burdens reduce growth and laying. Adults look like strands of spaghetti in droppings |
| Cecal worm (Heterakis gallinarum) | Ceca (two blind pouches of the gut) | Often causes few signs in chickens, but can carry the parasite that causes blackhead, which is serious in turkeys |
| Capillary worms (Capillaria spp.) | Crop, esophagus or small intestine, depending on species | Very thin, hard to see; heavy infections cause weight loss and diarrhea |
| Gapeworm (Syngamus trachea) | Windpipe and lungs | Blocks the airway, causing gasping, coughing and head-shaking |
| Tapeworms | Intestine | Spread through intermediate hosts such as flies, ants, grasshoppers, beetles, earthworms, slugs and snails |
Signs of Worms in Chickens
- Weight loss or poor growth despite eating
- Diarrhea
- Pale comb and wattles
- Fewer eggs
- Gasping, coughing or stretching the neck (gapeworm)
- Worms or worm segments in droppings
These signs have other causes too, including coccidiosis, mites and poor nutrition, so confirm worms before treating.
How to Check Your Flock for Worms
- Fecal test: collect fresh droppings from several birds and ask your vet or state poultry lab to check them. Because eggs are shed on and off, retest if you still suspect worms.
- Look at droppings: large roundworms and tapeworm segments can sometimes be seen, but many worms can’t be seen without a microscope.
- Necropsy: if a bird dies, a state lab examination can show exactly which worms (and other problems) were present.
Treating Worms
In the US, fenbendazole sold as Safe-Guard AquaSol is approved for chickens, including laying hens: 1 mg/kg a day in the drinking water for 5 days, with no egg withdrawal when used as labeled. It treats large roundworms and, in breeding and laying hens, cecal worms. Other dewormers are extra-label and need a vet’s prescription, and ivermectin in particular can leave residues in eggs for weeks. See our chicken deworming guide for when to treat and how.
Corid and Amprol contain amprolium, which treats coccidiosis, not worms. See Corid for chickens.
Preventing Worms
- Keep litter dry and clean; better sanitation lowers parasite levels in confined flocks.
- Rest or rotate outdoor areas where possible, so worm eggs don’t build up.
- Remember that tapeworms come from eating infected insects, earthworms, slugs and snails.
- Don’t deworm on a schedule. Treat when testing or signs show a need, to slow drug resistance.
FAQs
Can humans get worms from chickens?
The common chicken worms described here are parasites of birds. Wash your hands after handling chickens and their droppings, which protects against other germs such as Salmonella too.
What do worms in chicken poop look like?
Large roundworms look like strands of spaghetti. Tapeworm segments look like small, flat, white pieces. Many other worms are too small to see.
Can I eat eggs while treating for worms?
It depends on the dewormer. With Safe-Guard AquaSol used as labeled, there is no egg withdrawal. With other drugs, follow the label or your vet’s withdrawal time.
Do all chickens have worms?
Many chickens that range outdoors carry some worms. A light burden often causes no signs; treatment is for birds with problems or heavy counts.
Conclusion
Know the five main worm types, watch for the signs, and confirm with a fecal test before treating. Use an approved dewormer when one fits, involve your vet for anything else, and keep litter dry and clean.
Sources
- Merck Veterinary Manual: Overview of Helminthiasis in Poultry
- Alabama Cooperative Extension System: Backyard Poultry Worm Control
- Safe-Guard AquaSol (fenbendazole) label, DailyMed / US National Library of Medicine
- Frontiers in Veterinary Science (2025): ivermectin residues in eggs after topical use in chickens
- Merck Veterinary Manual: Coccidiosis in Poultry
Checked September 2026. Labels change, so always read the label on the product you buy. See our editorial policy for how we research health articles.
