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No, guinea pigs must never eat onions. Onions, spring onions, leeks, shallots, chives and garlic all belong to the same plant family and are toxic to guinea pigs, raw or cooked. The PDSA, Woodgreen and Burgess all list onion as a food to avoid. If yours has eaten any, ring a vet straight away, even before signs appear.
| Safe? | No, toxic |
| How much | None |
| How often | Never |
| Best served | Not at all, in any form |
| Watch out for | Leftovers, gravy, crisps, garden alliums |
Why are onions bad for guinea pigs?
Onions contain sulphur compounds that damage red blood cells. The ASPCA names the compound as n-propyl disulphide and lists the result as a type of anaemia, along with blood in the urine, weakness, fast breathing and a raised heart rate in animals that eat it. The vet-reviewed guide at The Vet Desk says onions are toxic to guinea pigs and should not be offered in any amount.
The UK charities agree. The PDSA lists onion, garlic and chives among foods to avoid, the RSPCA lists garlic, Woodgreen rules out onions, onion grass, leeks, chives and garlic, and Burgess calls onion and related vegetables, garlic and chives poisonous.
Which parts and forms are dangerous?
- Raw onion, red or white: no.
- Cooked, fried or caramelised onion: no. Cooking does not remove the danger.
- Onion powder, flakes and onion-flavoured crisps: no, these are concentrated.
- Spring onions (scallions), leeks, shallots: no.
- Chives and wild garlic: no, both are in the same family.
- Garlic: no.
- Ornamental alliums in the garden: keep grazing guinea pigs well away.
My guinea pig ate onion: what should I do?
- Remove the rest. Take away any onion or food containing it, and note roughly how much is missing.
- Ring a vet now. Call your vet or an out-of-hours vet straight away, even if your guinea pig seems fine. The Vet Desk says serious signs can take one to three days to show.
- Don't try home remedies. Guinea pigs can't vomit, so never try to make them sick. Keep hay and water available.
- Watch closely. Look for tiredness, not eating, heavy breathing, weakness, trembling, pale or yellow gums and red or dark urine, and tell the vet about any change.
The Vet Desk notes that there is no antidote, so vets give supportive care such as fluids and oxygen, and sometimes more in severe cases. The sooner they see your guinea pig, the better. Our guinea pig health guide covers other warning signs.
Safe foods to offer instead
For crunch and flavour, try celery, bell peppers or herbs such as parsley and coriander (cilantro). Other foods to keep off the menu include potatoes, avocado and mushrooms. See the safe food list, our guinea pig diet guide and the guinea pig care guide.
Onion questions
Can guinea pigs eat spring onions or leeks?
No. Spring onions (scallions), leeks and shallots are in the same Allium family as onions and carry the same compounds. Burgess calls onion and related vegetables poisonous, and Woodgreen names leeks and chives too. Keep the whole family out of the bowl.
Is cooked onion safe for guinea pigs?
No. Cooking does not make onion safe, and powders and dried flakes are concentrated. Any human food made with onion, such as stuffing, gravy, crisps, soup or sauces, should be kept away from guinea pigs.
How much onion is toxic to a guinea pig?
No safe amount is known, and the vet-reviewed guide at The Vet Desk says onions should not be offered in any amount. Guinea pigs weigh about 0.7 to 1.2 kg (1.5 to 2.6 lb), so even a small piece is a big dose for them. Ring a vet whatever the amount.
Can guinea pigs eat garlic?
No. Garlic is in the onion family and is on the RSPCA, PDSA and Woodgreen lists of foods guinea pigs must not eat. That includes garlic supplements, garlic-flavoured treats and garlic in leftovers. If yours has eaten some, treat it like onion and ring a vet.
