Complete Guide to Worming Chickens

Worms are one of the most common internal parasites affecting backyard chickens, and knowing how to manage them is a key part of keeping your flock healthy. This complete guide to worming chickens explains everything you need to know — from the types of poultry worms to how they spread, the signs of infestation, prevention strategies and the most effective treatments available in the UK.

Whether you’re new to chicken keeping or just need a refresher, this guide offers practical, accurate and up-to-date advice.

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What are poultry worms?

Poultry worms are parasitic organisms that typically live in a chicken’s digestive tract, although some species can also inhabit the lungs and windpipe. While a few worms in a chicken might not cause noticeable harm, large infestations can lead to malnutrition, illness, or even death if left untreated.

Understanding the main types of poultry worms helps you spot problems earlier and treat them more effectively.

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Types of worms found in chickens

There are several different types of worms that can affect chickens. Each has its own symptoms and risks:

• Caecal worm – Small white worms living in the digestive system. Usually harmless in small numbers and often symptomless.
• Gapeworm – Attaches to the windpipe or lungs, causing chickens to ‘gape’ for air. In severe cases, can suffocate the bird.
• Gizzard worm – Found in the gizzard; may lead to depression and weight loss.
• Hairworm / Threadworm / Capillaria – Extremely thin, lives in the crop, oesophagus and intestine. Can cause anaemia and green diarrhoea.
• Roundworm – Large, white, highly visible in droppings. May cause blockages, anaemia, and general ill health.
• Tapeworm – Lives in the intestines. Though long (up to 25cm), it rarely causes serious harm. Segments may appear in droppings.

For more in-depth information on these worms, you might also refer to academic resources such as Internal Parasites of Poultry by Dr Jacquie Jacob (University of Kentucky).

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How do worms affect chickens?

Worms feed on the nutrients inside a chicken’s digestive system, essentially robbing the bird of its food. This can lead to:

• Weight loss
• Weakness and lethargy
• Anaemia
• Diarrhoea
• Reduced egg production
• Increased vulnerability to other infections

In severe cases, worms can cause blockages in the digestive tract or lungs, internal bleeding, or even death.

Because chickens are almost constantly exposed to worm eggs in their environment, it’s unrealistic to expect them to be completely worm-free. The goal is to manage worm levels through regular treatment and good husbandry, preventing small infestations from becoming dangerous.

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How do chickens get worms?

Chickens can become infected with worms in two main ways:

1. Direct ingestion

Worm eggs are expelled in droppings. Chickens peck at the ground constantly, often swallowing eggs left in soil, bedding, or on contaminated feed.

2. Indirect ingestion

Some worms use intermediate hosts like earthworms, snails or insects. When chickens eat these hosts, the worms transfer to the chicken.

Eggs from certain worms can survive for months or even a year in the environment. That means even after worming your flock, reinfection is likely unless the coop and run are also cleaned thoroughly.

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Signs your chickens may have worms

Mild infestations can be difficult to detect, but as the worm burden increases, symptoms may include:

• Gaping (open-mouthed breathing)
• Head shaking and neck stretching (gapeworm)
• Weight loss despite normal appetite
• Lethargy or depression
• Pale comb or wattles (anaemia)
• Diarrhoea (sometimes greenish)
• Drop in egg production
• Visible worms or segments in droppings

How to check for worms

You can try the jar test:

• Collect a fresh dropping
• Dilute it in water inside a clear jar
• Let it settle, then inspect for worms with a torch

For a more accurate result, you can send a sample to a lab. The Worm Count Kit (available online via Amazon) is a home testing option that allows you to post a sample to Westgate Laboratories for professional analysis.

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How to prevent chickens getting worms

Prevention is better than cure. These good practices will help reduce worm loads:

1. Keep the coop and run clean

• Regularly clean out droppings and soiled bedding
• Use a chicken-safe disinfectant and diatomaceous earth on floors
• Rake dry runs to break up and remove faeces
• Keep feeders and drinkers elevated and out of reach of droppings

2. Sanitise the ground

Use ground sanitising powders (like Net-Tex) on the run to help kill worm eggs. Avoid leaving feed scattered where droppings may fall.

3. Manage mud and moisture

Worm eggs thrive in warm, damp soil. Reduce muddy patches by:

• Covering the run
• Filling in puddles
• Adding bark, sand or woodchip to problem areas
• Laying planks or stepping stones along chicken pathways

4. Rotate the run

If possible, move your run every few months. This gives the old patch time to recover and allows sunlight (which kills worm eggs) to disinfect the ground.

Top tip: Worm your chickens a day before moving the run to avoid immediate reinfection in the new space.

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How to worm chickens

Flubenvet – the gold standard

Most UK keepers use Flubenvet, a licensed poultry wormer that:

• Kills all common types of worm (except tapeworm in some cases)
• Is mixed with feed
• Requires no egg withdrawal (safe to eat eggs during treatment)
• Is typically given for 7 days and repeated after 3 weeks

You can buy Flubenvet 1% Premix powder to add to your feed (3g per 1kg of feed), or buy pre-medicated layers pellets with Flubenvet already added for convenience.

Affiliate tip: These pre-mixed feeds are often available on Amazon or poultry supply sites – ideal for affiliate links.

Safety precautions when handling Flubenvet

• Wear gloves and a dust mask (EN149 standard)
• Avoid breathing in powder
• Wash hands, arms, or face if they come into contact with the product
• Always follow the manufacturer’s instructions
• Safely dispose of packaging and any leftover treated feed

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Organic and natural alternatives

If you want organic eggs, you’ll need to avoid Flubenvet. Some keepers opt for Verm-X, a herbal wormer available in pellet or liquid form. While it doesn’t kill worms as effectively as Flubenvet, it may help maintain digestive health and reduce worm load.

Supporting products

• Apple cider vinegar – 1 tsp per litre of water (not in metal drinkers)
• Diatomaceous earth (food grade) – mix 5% into feed
• Garlic or pumpkin seeds – mild natural dewormers

While these may not replace worming entirely, they can support your chickens’ resistance between chemical treatments.

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How often should you worm chickens?

• New birds should be wormed immediately before joining your flock
• For established flocks:
  • Every 6 months is usually sufficient with good husbandry
  • If your run stays in one place, worm every 3 months
  • Use Verm-X or apple cider vinegar monthly as a natural support

Avoid overusing Flubenvet, as resistance can develop. Only treat when needed and based on worm count tests, symptoms, or seasonal routine.

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Final thoughts

Worms are almost inevitable in backyard chickens, but they don’t have to be a major problem. With smart prevention, occasional testing and effective treatment, you can keep your flock healthy and productive year-round.

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Disclaimer

This article is for informational purposes only and does not constitute veterinary advice. If you suspect your chickens have worms or other health issues, please contact a qualified poultry vet.