No. Onions contain compounds that destroy red blood cells in dogs, causing haemolytic anaemia. All forms are toxic — raw, cooked, powdered, and in gravy or takeaway food.

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. Use our onion toxicity calculator for guidance.

What are symptoms of onion poisoning?

Vomiting, diarrhoea, weakness, pale gums, rapid breathing, and dark urine may appear within one to five days as anaemia develops.

What should I do if my dog ate onion?

Phone your vet or Animal PoisonLine on 01202 509000 with the amount and your dog's weight. Do not wait for symptoms — anaemia may take days to appear.

Dog Health

Can Dogs Eat Onion UK?

Quick answer

**No — dogs must not eat onion.** Onions destroy red blood cells, causing **[anaemia](/glossary/anaemia)** that may appear days later. All forms count — raw, cooked, powder, and in gravy or curry. If your dog ate onion, use our **[onion toxicity calculator](/onion-toxicity-calculator)** and phone your vet or **Animal PoisonLine on 01202 509000**.

Key takeaways

No. Onions contain compounds that destroy red blood cells in dogs, causing haemolytic anaemia. All forms are toxic — raw, cooked, powdered, and in gravy or takeaway food.
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. Use our onion toxicity calculator for guidance.
Vomiting, diarrhoea, weakness, pale gums, rapid breathing, and dark urine may appear within one to five days as anaemia develops.

The full picture

Causes, home monitoring, treatment options and the exact signs that mean call your vet — in the complete guide.

Read the full guide Check symptoms

Frequently Asked Questions

Can dogs eat onion?: No. Onions contain compounds that destroy red blood cells in dogs, causing haemolytic anaemia. All forms are toxic — raw, cooked, powdered, and in gravy or takeaway food.
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. Use our onion toxicity calculator for guidance.
What are symptoms of onion poisoning?: Vomiting, diarrhoea, weakness, pale gums, rapid breathing, and dark urine may appear within one to five days as anaemia develops.
What should I do if my dog ate onion?: Phone your vet or Animal PoisonLine on 01202 509000 with the amount and your dog's weight. Do not wait for symptoms — anaemia may take days to appear.

Reviewed 2026-07-19 against UK veterinary guidance · Information only — not a substitute for seeing your vet.