Guinea pigWhat can a guinea pig eat?
20 foods checked against vets’ sources: what’s fine, what only now and then, and what never.
Every day
Grass hay always available: it's the biggest part of the diet. Every day, fresh vegetables and a new portion of guinea pig pellets, as the bag says (don't just top up the bowl: vitamin C breaks down). Vitamin C: at least 10 mg per kg of body weight a day, 30 mg if pregnant.
No food matches: if it isn’t on the list, ask your vet before giving it.
Never
AvocadoNo
It's one of the foods that can harm or poison guinea pigs.
Source: RSPCA: What To Feed a Guinea Pig
Bread, dairy, sweets and chocolateNo
These are people foods that don't suit a herbivore: no bread, crackers, cereal, milk, cheese, yogurt or chocolate.
Source: NYC Animal Care Centers: Guinea pig care packet (2025)
GrapesNo
Best avoided: the RSPCA warns that grapes can be poisonous to rodents, and guinea pigs are rodents. Choose other fruit.
Iceberg lettuceNo
It's a watery lettuce that can cause diarrhea: choose romaine or little gem instead.
Source: RSPCA: What To Feed a Guinea Pig
Onion, garlic and chivesNo
They're not safe for guinea pigs: they can poison them or upset their stomach.
Source: PDSA: Your guinea pig’s diet
Oranges and other citrusNo
The RSPCA lists them among foods to avoid. Vegetables such as bell peppers are better sources of vitamin C.
Source: RSPCA: What To Feed a Guinea Pig
PotatoesNo
They're among the foods that can harm guinea pigs, skin included; the plant is poisonous too.
Source: PDSA: Your guinea pig’s diet
Seeds and nutsNo
Too fatty and sugary for guinea pigs: no seeds, nuts, or treats with seeds and corn.
Source: Royal Veterinary College: Guinea pig feeding guidelines (2022)
Only now and then, a little
AppleA little
Fine as a treat, but it's sugary; remove the pips, which are poisonous.
How much: A quarter of an apple at most, a few times a week (the RVC says once or twice).
Source: RSPCA: What To Feed a Guinea Pig
BananaA little
Only as a treat, very little: it's very sugary and too much can cause constipation.
How much: A small piece, once or twice a week at most.
Source: Royal Veterinary College: Guinea pig feeding guidelines (2022)
Broccoli, spinach and kaleA little
Fine in small amounts a few times a week: they're high in calcium (or sugar) and can cause problems in large amounts.
How much: A little, a few times a week.
Source: RSPCA: What To Feed a Guinea Pig
CarrotA little
Only in small pieces, as a treat: it's sugary.
How much: A small piece, a few times a week.
Source: RSPCA: What To Feed a Guinea Pig
StrawberriesA little
Fine as a treat: they have vitamin C but also plenty of sugar.
How much: A few, once or twice a week.
Source: Royal Veterinary College: Guinea pig feeding guidelines (2022)
Fine
Bell pepperYes
One of the best vegetables: it's rich in vitamin C, which guinea pigs can't make themselves and must get from food.
How much: As part of the daily fresh veg: about one cup per guinea pig, with 5-6 different kinds rotated.
Source: RSPCA: What To Feed a Guinea Pig
CeleryYes
Can be given often, leaves included, rotated with other vegetables.
Source: RSPCA: What To Feed a Guinea Pig
CucumberYes
Fine often: it's a low-sugar vegetable.
Source: RSPCA: What To Feed a Guinea Pig
Hay and grassYes
It's the core of the diet: it keeps the gut moving and wears down teeth that never stop growing. Never give lawnmower clippings, which ferment and make guinea pigs ill.
How much: Always available: every day at least a pile of hay as big as your guinea pig.
Source: PDSA: Your guinea pig’s diet
ParsleyYes
Fine often, rotated with other greens; don't overdo it, as it's high in calcium.
How much: Often, rotated with other greens, but never in large amounts (it's high in calcium).
Source: RSPCA: What To Feed a Guinea Pig
Romaine lettuceYes
Fine often, like little gem lettuce; but not iceberg.
Source: RSPCA: What To Feed a Guinea Pig
Tomato (the fruit)Yes
The fruit is fine; the leaves, stems and plant are poisonous.
Source: PDSA: Your guinea pig’s diet
When to call the vet Emergency: who to call
What other pets can eat
Rabbit Hamster Pet rat Ferret Canary Budgies Cockatiel Lovebirds Tortoise Red-eared slider Leopard gecko Bearded dragon Goldfish Betta fish Dogs and cats: can my pet eat it?
Sources
- PDSA: Your guinea pig’s diet (checked on October 14, 2026)
- RSPCA: What To Feed a Guinea Pig (checked on October 14, 2026)
- Royal Veterinary College: Guinea pig feeding guidelines (2022) (checked on October 14, 2026)
- RSPCA: What To Feed a Pet Hamster (checked on October 14, 2026)
- NYC Animal Care Centers: Guinea pig care packet (2025) (checked on October 14, 2026)