What do guinea pigs eat? A step-by-step feeding guide

A guinea pig’s diet should be based on hay or safe fresh grass that is available at all times. A daily diet is supplemented with a variety of vegetables and greens, a small portion of complete guinea pig pellets, and fresh water. The diet must provide vitamin C, as a guinea pig’s body cannot produce it. Fruit and high-calorie treats should not replace hay or daily vegetables.

What should a guinea pig eat every day?

The easiest way to plan a diet is to follow a hierarchy in which fibrous food is available without restriction, while higher-calorie additions make up increasingly smaller portions of the diet.

As a general starting point for a healthy adult guinea pig, PDSA suggests about one tablespoon of pellets and one cup of fresh vegetables and greens per animal per day. This is not a therapeutic amount or one that is automatically suitable for every guinea pig. The portion should be assessed alongside body weight, condition, age, activity level, health status, and advice from a veterinarian.

Hay and grass – the most important part of the diet

Good hay should smell fresh, be dry, and be free of mold, excessive dust, and contaminants. Its color may vary depending on the plants and drying method, so an intense green color alone does not guarantee quality. If the hay smells musty, is damp, or is moldy, do not feed it.

Place hay so that each guinea pig can eat freely without being pushed away by a companion. A good option is to provide several spacious feeding areas, including near hiding places. Hay can also be used for safe foraging, as described in the guide on, how to enrich a guinea pig’s life.

Fresh grass can be a valuable food if it comes from an area free of pesticides, exhaust fumes, other animals’ droppings, and poisonous plants. Introduce it gradually. Do not feed grass clippings from a lawn mower: the compacted, warming mass ferments quickly and can harm the digestive tract.

Vegetables, greens, and vitamin C

A daily selection of fresh plants should be varied, rather than relying on the same food all the time. For many healthy guinea pigs, suitable options include bell pepper, cucumber, chicory, romaine lettuce, and safe, correctly identified herbs. Wash vegetables, remove spoiled parts, and serve them in pieces that do not pose a risk of getting stuck.

Bell peppers and selected green vegetables help provide vitamin C. Its content decreases during prolonged storage of food and fresh produce. Guinea pig pellets fortified with vitamin C should be fresh and stored in an airtight container, in a dry place, and according to the manufacturer’s instructions – it is best not to buy a very large package that will remain open for a long time.

Not every guinea pig that is fed properly needs an additional supplement. Growing, pregnant, ill or recovering guinea pigs may have different needs. The type of supplement and the dose should be determined with a veterinarian who treats exotic animals. Do not routinely add vitamin C to the water bottle: it is unstable, and the changed taste of the water may discourage your pet from drinking.

Can guinea pigs eat fruit?

Fruit is not needed as a regular part of the diet. It contains a lot of sugar, so a small piece can be given as an occasional treat if your guinea pig’s health and weight allow. Do not replace vegetables rich in vitamin C with fruit.

How to choose guinea pig pellets?

Choose uniform pellets made for guinea pigs, based on grasses and fortified with stabilized vitamin C. Muesli-style mixes with colorful pieces, seeds and grains encourage selective feeding, which means your pet may not eat a balanced portion.

Pellets are a supplement, not a substitute for hay. Do not keep topping up the bowl with fresh food on top of the old. Remove leftovers daily and measure out a fresh portion. If your guinea pig is growing, underweight, pregnant, nursing young, or has a chronic illness, the portion size should be determined individually with a veterinarian.

What should you not feed a guinea pig?

Do not feed animal products, sweets, salty snacks, bread or highly processed food. The following are also unsafe or unsuitable:

• onions, garlic, chives and other plants in the onion family;
• potatoes and their skins;
• avocado;
• rhubarb and its leaves;
• mushrooms;
• tomato leaves and stems – the ripe fruit is a separate, edible part of the plant;
• beans and other dried legume seeds;
• nuts, pits and seed mixes;
• ornamental plants or plants picked outdoors that have not been identified with complete certainty;
• moldy, spoiled or contaminated food, or food from a sprayed area.

Lettuce is not one single dietary category: romaine lettuce can be part of a varied diet, whereas nutritionally poor iceberg lettuce is best avoided. Cabbage-family vegetables are not automatically poisonous either, but some should be fed in small amounts, with your guinea pig’s tolerance monitored. For urinary tract, kidney, dental or digestive conditions, the diet should be determined by a veterinarian.

How to change your guinea pig’s diet safely?

Introduce new pellets, grass and unfamiliar vegetables gradually. When changing food, mix a small amount of the new product with the current one and increase its proportion over about two to four weeks. Introduce fresh plants one at a time and in small amounts. This makes it easier to notice soft stools, bloating, reduced appetite or reluctance to eat a particular food.

Observe whether each guinea pig is actually eating. In a pair, one guinea pig may prevent the other from accessing the bowl or hay, so there should be several resources. You can read more about organizing the space in the guide to housing for guinea pigs, while the importance of compatible companionship is explained in the article about why guinea pigs are social animals.

Loss of appetite – when is veterinary care needed?

A guinea pig should eat hay regularly, including between its main feeding times. A reduced appetite, choosing only soft food, food falling out of the mouth, drooling, weight loss, or fewer droppings may indicate, among other things, pain, a dental problem, or a digestive issue. Don’t try to address this solely by changing the food brand.

Contact an exotic animal veterinarian urgently, if your guinea pig stops eating, has a noticeably reduced appetite, stops passing droppings or produces far fewer, has a bloated abdomen, is very lethargic, or shows signs of pain. Guinea pigs can quickly become weak, so don’t wait until the next day or give them human medication yourself.

Regular weighing helps you notice changes sooner, even when they aren’t visible under the fur. Record the weight, how much food was eaten, what the droppings look like, and when the symptoms started – this information may help the veterinarian.

Sources

• PDSA – Your guinea pigs’ diet (veterinary recommendations; English-language source).
• RSPCA – A healthy diet for guinea pigs (English-language source).
• Merck Veterinary Manual – Routine Care of Guinea Pigs (English-language source).
• RSPCA – Guinea pig health and welfare (symptoms requiring consultation; English-language source).

Last content review: September 23, 2026. This article is for educational purposes and does not replace individualized advice from a veterinarian.