--- title: "Onion & Garlic Poisoning in Pets UK" description: "Onions, garlic, leeks and chives damage red blood cells in dogs and cats. UK g/kg bands, leftover curry risk, calculator, and Animal PoisonLine steps." url: "https://pethealth.org.uk/health/onion-garlic-poisoning-pets-uk" canonical: "https://pethealth.org.uk/health/onion-garlic-poisoning-pets-uk" date_published: "2026-06-25" date_modified: "2026-08-13" source: "PETHEALTH+" --- # Onion & Garlic Poisoning in Pets UK **Onions, garlic, leeks, chives, and shallots are toxic to dogs and cats.** They destroy red blood cells, causing anaemia that may appear days later. If your pet ate onion-rich food — including gravy, curry, pizza, or garlic bread — use the onion & garlic calculator, then phone your vet or **Animal PoisonLine on 01202 509000** with the amount and your pet's weight. ## Why alliums poison pets Plants in the **Allium** family — onion, garlic, leeks, chives, shallots, and spring onions — contain compounds that damage **red blood cells** in dogs and cats, causing **haemolytic anaemia**. Unlike chocolate, effects are **not always immediate**. Damage accumulates over one to five days as cells break down. That delay is why “they seem fine” is a dangerous stopping rule. All forms are toxic: - Raw, fried, or roasted onion and garlic - **Onion and garlic powder** in stock cubes, gravies, and processed foods - Dehydrated onions in crisps, soup mixes, and ready meals - Leftover takeaway — curries, stir-fries, and Chinese dishes often contain concentrated alliums Cats are generally **more sensitive** than dogs, but both species can become seriously ill. ## Approximate risk by amount | Rough guide | Risk | |---|---| | Around 15–30 g onion per kg body weight | Haemolytic anaemia risk in dogs commonly cited | | Garlic (any form) | Still toxic — often more concentrated than onion by weight | | Onion/garlic powder, gravy, curry | Easy to underestimate — treat as potentially toxic | | Cats | Generally more sensitive — never share allium-containing food | These are approximate bands only. Use the [onion & garlic calculator](/onion-toxicity-calculator) to turn leftover weight into a prompt, then **phone**. Individual sensitivity varies; the tool is not a diagnosis. ## Common UK exposure routes - **Sunday roast gravy** and stuffing - **Garlic bread** and pizza toppings - **Baby food** containing onion powder (never feed to cats) - **Stock cubes** dissolved in pet food by mistake - **Leftover Chinese or Indian takeaway** - **Homemade treats** with garlic (popular online recipes are unsafe) - Shopping bags left in the hallway — whole onions are a chew toy for some dogs Owners often underestimate powdered forms — a teaspoon of onion powder can be more concentrated than a slice of fresh onion. “Just the gravy” is still allium. ## Symptoms of allium toxicosis Signs may develop **1–5 days** after ingestion: - Vomiting and diarrhoea (early) - Weakness and lethargy - **Pale or yellow-tinged gums** - Rapid breathing or panting at rest - Dark or reddish-brown urine (haemoglobinuria) - Collapse in severe cases Chronic small exposures — such as garlic supplements marketed for fleas — can cause gradual anaemia. Avoid any garlic products for pets. Flea control belongs with [licensed preventatives](/health/fleas-and-ticks-in-pets), not kitchen herbs. ## What to do if your pet ate onion or garlic 1. **Estimate the amount** — type of food, approximate weight, time eaten 2. Run the [onion calculator](/onion-toxicity-calculator) if you have numbers 3. **Phone your vet or Animal PoisonLine (01202 509000)** — do not wait for symptoms 4. **Do not induce vomiting** unless your vet instructs you 5. Bring **food packaging or takeaway containers** if available 6. If advised to go in out of hours, use the [out-of-hours directory](/vets/filter/out-of-hours) Veterinary treatment may include: - Induced vomiting and activated charcoal if ingestion was recent - **Blood tests** monitoring red cell count and haemoglobin - **IV fluids** and oxygen support if anaemic - **Blood transfusion** in severe cases Hospitalisation allows monitoring as anaemia may worsen over several days. Chocolate and grapes are different poisons with different clocks — [chocolate](/health/chocolate-poisoning-in-dogs) and [grapes](/health/grape-poisoning-in-dogs) — but the first move is still the phone. ## Delayed bloods and gravy maths Vets often repeat a red-cell count over several days. A normal result tonight does not close the case if a lot of onion went in this afternoon. Pale gums and dark urine later in the week are why you were told not to wait. Gravy is easy to get wrong: a few tablespoons on a small terrier or a cat can sit in the cited g/kg band. Powdered onion in a stock cube is concentrated. Baby food labelled “with onion” is a classic cat exposure when owners think they are being kind. If both a dog and a cat stole from the same plate, run the calculator twice and phone for both. Cats generally need a lower threshold of concern. ## Prevention - Never share **human meals** containing onion, garlic, or leeks - Read labels on **stock cubes, gravies, and baby food** - Warn guests and children not to feed table scraps - Avoid **garlic flea treatments** and herbal supplements containing alliums - Store onions and garlic out of reach ## FAQs ### How much onion is toxic to dogs? As little as 15–30 g per kg of body weight can cause harm — a few tablespoons of onion gravy or leftover curry may be enough for a small dog. All forms count: raw, cooked, powdered, and dehydrated. Use the onion calculator, then phone your vet. ### Is garlic less toxic than onion? Garlic is still toxic — it contains the same compounds (thiosulphates and organosulphoxides) that damage red blood cells. Do not assume garlic supplements or leftover garlic bread are safe. ### What are symptoms of onion poisoning in pets? Vomiting, diarrhoea, weakness, pale gums, rapid breathing, and dark urine appear within one to five days as red blood cells are destroyed (haemolytic anaemia). ### Can cats eat food with onion powder? No. Cats are more sensitive than dogs to allium toxicity. Baby food, stock cubes, and takeaway meals often contain onion or garlic powder — check labels before sharing human food. ### Should I wait to see if they get ill? No. Red-cell damage can take days. Early decontamination is the point of phoning now. A pet that 'seems fine tonight' is not cleared. ## Sources - [RSPCA — Foods poisonous to dogs](https://www.rspca.org.uk/adviceandwelfare/pets) - [Animal PoisonLine](https://www.animalpoisonline.co.uk) - [PDSA — Foods dogs should avoid](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub) - [BVA — Pet poisons](https://www.bva.co.uk) Canonical HTML: https://pethealth.org.uk/health/onion-garlic-poisoning-pets-uk Last modified: 2026-08-13