Foods that are toxic to chickens
The foods that never go in the run, what makes each one dangerous, and what to do if a hen eats one.
Most kitchen food is safe for chickens in small amounts. A short list is not, and a few of them are things backyard keepers are often told are fine. Every entry below is checked against a veterinary reference, a government source or poultry extension advice, listed at the end. For everything else, see what chickens can eat.
- Take the food away and check the rest of the flock.
- Make sure there is clean, fresh water.
- Call a vet, ideally one who treats poultry (RSPCA Australia suggests a vet with poultry experience), or an emergency vet after hours. Many bird and exotics vets see chickens.
- Tell them what was eaten, roughly how much, and when. Take the packaging, a sample or a photo.
- Do not try home remedies such as oil, salt water or making the bird vomit unless the vet tells you to.
Signs that a hen needs a vet whatever she ate: sitting fluffed up and quiet, not eating or drinking, weakness or wobbling, a limp neck, breathing with her beak open when it is not hot, a pale or dark comb, or watery droppings that do not settle within a day.
The list at a glance
| Food | Toxin | Main risk |
|---|---|---|
| Avocado | Persin | Heart damage, breathing trouble |
| Chocolate, cocoa | Theobromine, caffeine | Many species poisoned |
| Coffee, tea, caffeine | Caffeine | Same family as chocolate |
| Alcohol, fermenting fruit | Ethanol | Listed as toxic by UC Davis |
| Raw or dried beans | Phytohaemagglutinin (lectin) | Destroyed only by thorough boiling |
| Green or sprouted potato, peel, plant | Solanine, chaconine | Gut, nerve and heart effects |
| Tomato, capsicum, eggplant leaves; green tomato | Glycoalkaloids | Avoid, per UC Davis |
| Rhubarb leaves | Oxalic acid | Binds calcium, kidney damage |
| Onion | Sulfur oxidants | Anaemia |
| Garlic | Sulfur oxidants | Anaemia, at a smaller dose than onion |
| Mouldy or rotting food | Mycotoxins, botulism toxin | Liver damage, paralysis |
| Salty food | Sodium chloride | Salt poisoning, worse without water |
| Apple and pear seeds, fruit stones | Cyanogenic compounds | Seeds carry far more than flesh |
| Wild mushrooms | Various | Some are deadly |
Avocado
What is in it: persin. The MSD Veterinary Manual links the fruit, leaves, stems and seeds to poisoning, and names the leaves as the most toxic part.
The risk: damage to the heart muscle, with breathing trouble. Pet birds such as budgies and canaries are the most sensitive; chickens are less so but are still on the list of animals poisoned. There is no test for it and no antidote, so treatment is supportive care only.
What to do: feed no part of the fruit or tree, and keep fallen leaves and fruit out of the run if you have a tree nearby. If a hen has eaten avocado and is quiet, fluffed up or breathing hard, call a vet.
Chocolate and cocoa
What is in it: theobromine and caffeine, the methylxanthines. Dark and cooking chocolate and cocoa powder carry the most.
The risk: the MSD Veterinary Manual says many species are susceptible, and reports deaths in livestock fed cocoa by-products and in animals that ate cocoa bean hull mulch. The Better Health Channel lists chocolate among the foods not to give chickens.
What to do: never feed it, keep cakes, biscuits and cereals containing chocolate out of the scrap bucket, and do not use cocoa hull mulch where hens scratch. Call a vet if a hen has eaten chocolate.
Coffee grounds, tea and other caffeine
What is in it: caffeine, the same family of toxins as the theobromine in chocolate.
The risk: used grounds and tea leaves still contain caffeine, and the MSD Veterinary Manual counts caffeine as one of the toxic principles in chocolate poisoning. Energy drinks and caffeine tablets are far stronger.
What to do: compost grounds and tea leaves in a bin the hens cannot reach. Call a vet if a hen has eaten a quantity.
Alcohol and fermenting fruit
The risk: UC Davis poultry extension lists alcohol among the things that can be toxic to chickens. Windfall fruit that has started to ferment also carries mould.
What to do: never give drinks or alcohol-soaked food, and rake up fermenting windfalls.
Raw or undercooked dried beans
What is in it: phytohaemagglutinin, a lectin found at high levels in raw kidney beans and other dried beans.
The risk: UC Davis poultry extension says to avoid raw beans. Soaking does not remove the lectin; a 2018 food poisoning investigation in France traced illness to beans that had been soaked and undercooked. Thorough boiling destroys it.
What to do: only feed beans that have been boiled until fully soft, the way you would cook them to eat. Plain cooked beans are a good treat (see cooked beans).
Green or sprouted potatoes, peel and plants
What is in it: solanine and chaconine, glycoalkaloids concentrated in green skin, sprouts and eyes, old and sprouted tubers, and the leaves, stems and berries of the plant (Massey University Poisonous Plants database).
The risk: Massey lists poultry among the animals poisoned. Solanine irritates the gut and affects the nervous system and heart. UC Davis poultry extension says to avoid the green areas of potatoes.
What to do: plain cooked potato that was never green is fine as a treat. Cooking does not make green potato safe, so green or sprouting potatoes and peel go in the bin, not the run. Keep hens out of the potato patch.
Tomato, capsicum and eggplant leaves, stems and green fruit
What is in it: glycoalkaloids, the nightshade family's natural defence, highest in leaves, stems and unripe fruit.
The risk: UC Davis poultry extension says to avoid tomato leaves and the leaves of pepper, potato, eggplant and other nightshade plants.
What to do: ripe tomatoes, capsicums and cooked ripe eggplant are fine. Keep vines, prunings and green fruit out of the run and out of compost the hens scratch through.
Rhubarb leaves
What is in it: oxalic acid and soluble oxalates, in the leaf blade (MedlinePlus). The stalks contain very little (Pet Poison Helpline).
The risk: oxalates bind calcium, which a laying hen needs for every shell, and in quantity cause weakness and kidney damage.
What to do: fence the rhubarb patch off from the hens and keep the leaves out of their compost. There is no reason to feed the stalks either.
Onion
What is in it: sulfur compounds that damage red blood cells, in raw, cooked, dried and powdered onion (MSD Veterinary Manual).
The risk: anaemia. Poisoning depends on dose and signs often appear days later. The MSD Veterinary Manual records poisoning in farm animals fed onions, and the Better Health Channel says not to give chickens onions. Strong-tasting scraps such as onion can also flavour eggs (US Cooperative Extension).
What to do: do not feed onion scraps, and do not make onion-heavy leftovers a habit. Call a vet if a hen that has eaten onion becomes weak, pale in the comb or short of breath.
Garlic
What is in it: the same red-cell-damaging compounds as onion. The MSD Veterinary Manual says garlic is 3 to 5 times more toxic than onion in the animals studied.
The risk: the same as onion, at a smaller dose. Garlic is often sold as a poultry tonic; we found no vet source that supports feeding it, and the Better Health Channel names garlic among the foods to avoid.
What to do: do not feed raw garlic or garlicky leftovers on purpose. If you are thinking of a garlic product for the flock, ask a poultry vet first.
Mouldy or rotting food
What is in it: mycotoxins such as aflatoxins, ochratoxins and fumonisins, made by moulds on grain, nuts, bread and stored feed (MSD Veterinary Manual), and in rotting food, the bacteria that cause botulism.
The risk: mycotoxins damage the liver, gut and immune system and cut laying. Botulism toxin builds in decaying matter and maggots, and poisons birds that eat them. Biosecurity Tasmania warns that wet feed can grow highly toxic bacteria.
What to do: if it is too mouldy for you, it is too mouldy for them. Throw out mouldy bread, fruit, nuts and feed, and any feed that is crusted or lumpy. Pick up uneaten scraps the same day. A hen that is floppy, cannot hold her head up or has a limp neck needs a vet straight away.
Salty food
What is in it: sodium chloride, in chips, crackers, salted nuts, cured meats, soy sauce, stock, gravy and salty cheese.
The risk: the MSD Veterinary Manual lists poultry among the animals most often affected by salt poisoning. The danger rises sharply when water runs short, such as a waterer that runs dry on a hot day.
What to do: keep salty food out of the scrap bucket and make sure water never runs out. If hens have eaten something very salty, give fresh water and call a vet; do not force large amounts of water.
Apple and pear seeds, stone fruit kernels
What is in it: cyanogenic compounds. The MSD Veterinary Manual notes that seeds and leaves carry far more than the fleshy part of a fruit.
What to do: core apples and pears and take the stones out of stone fruit. The flesh is a good treat (see apple and pear).
Wild mushrooms
The risk: some wild fungi are deadly to animals and people, and they cannot be told apart safely by eye. Plain shop-bought mushrooms are fine.
What to do: pull out mushrooms that come up in the run, and call a vet if a hen has eaten one and seems unwell.
Toxic plants in and around the run
The same rules apply to what grows where hens forage. Keep them away from avocado trees, rhubarb, potato plants and tomato vines, and pull out mushrooms as they appear. Hens with plenty of feed and greens rarely eat enough of a bitter plant to harm themselves, but a bored, hungry flock in a bare run will try anything, so keep the feeder full.
Common questions
What should I do if my chicken ate something toxic?
Remove the food, make sure the flock has clean water, and call a vet, ideally one who treats poultry, or an emergency vet after hours. Tell them what was eaten, roughly how much and when, and take the packaging or a sample with you.
Is avocado poisonous to chickens?
Yes. The MSD Veterinary Manual lists chickens among the animals poisoned by avocado. Chickens are less sensitive than pet birds such as budgies and canaries, but there is no safe amount to rely on, and the leaves are the most toxic part.
Can chickens eat onion or garlic?
Do not feed them on purpose. Both contain compounds that damage red blood cells, garlic more strongly than onion, and the Victorian Government's Better Health Channel says to avoid giving chickens either.
Can chickens eat chocolate?
No. Chocolate contains theobromine and caffeine, which are toxic to many animals. Dark and cooking chocolate are the most concentrated.
Are tomato plants poisonous to chickens?
Ripe tomatoes are fine. The leaves, stems and green fruit are nightshade parts, and poultry extension advice says to keep them out of the run.
Sources we checked
- MSD Veterinary Manual, Avocado toxicosis in animals
- Massey University, Poisonous Plants database: avocado
- MSD Veterinary Manual, Chocolate toxicosis in animals
- MSD Veterinary Manual, Garlic and onion (Allium spp) toxicosis in animals
- Better Health Channel (Victorian Government), Keeping backyard chickens
- Cooperative Extension (poultry.extension.org), Feeding chickens for egg production in small and backyard flocks
- MSD Veterinary Manual, Salt toxicosis in animals
- MSD Veterinary Manual, Mycotoxicoses in poultry
- MSD Veterinary Manual, Botulism in poultry
- Biosecurity Tasmania, Backyard Poultry: a guide for hobby farmers (PDF)
- MSD Veterinary Manual, Cyanide poisoning in animals
- UC Davis and UC Agriculture and Natural Resources, Feeding your Flock (Pitesky and Reimers, PDF)
- Massey University, Poisonous Plants database: potato
- MedlinePlus (US National Library of Medicine), Rhubarb leaves poisoning
- Pet Poison Helpline, Rhubarb
- From foodborne disease outbreak to investigation: the plant toxin trap, Brittany, France, 2018 (PMC10467087)
- RSPCA Australia, Essential tips to care for backyard chickens
Sources checked in October 2026. Feeding rules and vet advice change, so we recheck this page every year. If a hen is unwell, call a vet: this page is general information, not a diagnosis.