What Do Guinea Pigs Eat? Diet & Feeding Guide

Guinea pigs are herbivores, meaning they only eat plants and plant-based foods. Your pet guinea pig's diet should be based on high-quality hay, commercially available pelleted food made specifically for guinea pigs, and limited amounts of fresh vegetables and fresh fruit. An imbalance in nutrition can lead to chronic diarrhea, obesity, and even dental disease. When introducing new foods into your guinea pig's diet, do so gradually--abrupt or significant dietary changes may cause your guinea pig to stop eating and potentially develop life-threatening gastrointestinal problems.

What guinea pigs eat: the foundation of a wholesome diet

Guinea pigs thrive on a straightforward, plant-based menu built around a few core staples. The short answer: unlimited timothy hay, a measured daily portion of fortified pellets, and a small handful of fresh vegetables make up a nutritious, balanced diet for most guinea pigs. Understanding each component — and how much of it to offer — sets your little one up for a long, active life.

Hay: the non-negotiable foundation

Hay should make up roughly 70–80% of your guinea pig's daily diet and should be available around the clock https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals. Timothy hay is the gold standard for adult guinea pigs — its long fiber strands support healthy digestion and keep teeth worn down naturally, since guinea pig teeth never stop growing. Orchard grass and meadow hay are solid alternatives if your guinea pig turns his nose up at timothy.

Alfalfa hay is higher in calcium and protein, making it appropriate for young guinea pigs (under six months) and pregnant or nursing females, but it should be phased out for healthy adults to avoid urinary issues https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals.

Pellets: fortified and measured

A small daily serving of high-quality, guinea-pig-specific pellets rounds out the nutrients hay alone can't provide. Look for plain, timothy-based pellets without added seeds, dried fruit or colored bits — those extras add sugar and calories without nutritional benefit https://sites.tufts.edu/petfoodology/.

Why guinea-pig-specific pellets matter: Guinea pigs cannot synthesize their own Vitamin C — they must get it from food. Quality guinea pig pellets are fortified with Vitamin C to help fill that gap https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals. Check the expiration date on every bag; Vitamin C degrades quickly once a package is opened.

Fresh vegetables: variety with purpose

Fresh vegetables add Vitamin C, hydration and enrichment to your guinea pig's day. Aim for about one packed cup of fresh veggies per guinea pig, per day, offered in two smaller servings if possible. Rotate through a variety so your guinea pig gets a broad range of nutrients and doesn't fixate on one food.

Vegetables guinea pigs can eat regularly:

• Romaine lettuce — hydrating and mild; a reliable daily staple
• Green and red leaf lettuce — similar benefits to romaine; rotate freely
• Bell peppers (any color) — one of the richest plant sources of Vitamin C; red bell pepper in particular is an excellent daily choice https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals
• Cucumber — high water content; great for hydration on warm days
• Zucchini — mild and well-tolerated by most guinea pigs
• Cilantro — a favorite herb that also delivers Vitamin C
• Parsley — nutritious, but feed in moderation due to higher calcium content
• Kale and spinach — nutritious in small amounts; limit frequency because of oxalates and calcium

Vegetables to offer only occasionally (once or twice a week):

• Carrots and carrot tops — higher in natural sugar; tops are actually more nutritious than the root
• Tomato (ripe only, no leaves or stem) — acidic, so small pieces only
• Broccoli and cauliflower — can cause gas in some guinea pigs; introduce slowly

Fresh fruit: a small treat, not a staple

Fruit is naturally higher in sugar, so think of it as an occasional reward rather than a daily offering. A small slice of apple (seeds removed), a few blueberries or a thin wedge of watermelon once or twice a week is plenty. Treats of all kinds — including fruit — should stay at or below 10% of your guinea pig's total daily diet.

Fresh water, always

Clean, fresh water must be available at all times. Most guinea pigs do well with a drip-style water bottle attached to their habitat, though a heavy ceramic bowl works too — just rinse and refill it daily to prevent bacterial buildup https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals.

If you're ever unsure whether a specific food is appropriate for your guinea pig, check with your veterinarian before offering it — especially when introducing anything new to a young or sensitive pet.

Foods guinea pigs cannot eat

There are several foods that guinea pigs should not be offered-for various reasons. Some foods can be toxic or upset the GI tract, while others are too high in fat or sugar, may be a choking hazard, or have no nutritional value. Consult your veterinarian as to which foods are unsafe for guinea pigs.

A short list of the foods to avoid feeding your guinea pig includes:

• Chocolate (or anything else containing caffeine)
• Onions
• Garlic
• Mushrooms
• Iceberg lettuce
• Avocados
• Nuts
• Potatoes
• Seeds
• Corn kernels
• Peanut butter
• Rhubarb
• Dairy products
• Bread
• Meat

Never offer your guinea pig any plants, flowers, or grass from your yard or garden, as they may contain pesticides, molds, or other infectious agents. Many houseplants are also toxic. Consult your veterinarian about what plants are potentially toxic to guinea pigs before bringing a plant home, and always supervise your little pet when they are out of their habitat.

How often do guinea pigs eat?

Feed your guinea pig on a consistent schedule-twice a day, morning and evening.

Because guinea pigs will overeat if given the chance, be sure not to overfeed pelleted food, as it is predominantly carbohydrate and can lead to diarrhea and decreased appetite. Hay contains healthy fiber and should be made available at all times.

A small quantity of fresh vegetables-and occasional high-fiber fruit-such as apples or pears-should be offered daily to help keep guinea pigs hydrated. Discard fresh fruits or vegetables that are left uneaten after 10-12 hours so they don't spoil. Fresh water must be constantly available, especially during warmer weather, as guinea pigs are susceptible to heat stroke. Some guinea pigs like to drink from a bottle, while others prefer a bowl. If using a bottle, rinse your guinea pig's water bottle out daily and clean with hot water and a bottle brush weekly.

Scurvy in guinea pigs and the need for Vitamin C

Since guinea pigs are unable to synthesize vitamin C in their bodies, they are at risk of developing a vitamin C deficiency-also called scurvy. To combat scurvy, your guinea pig needs to ingest 30-50 mg of vitamin C daily. Pellets and treats fortified with vitamin C can provide some of this vital nutrient, but guinea pigs need more vitamin C than that. You can provide additional Vitamin C in liquid or tablet form directly into your guinea pig's mouth-rather than in their food or water-to ensure they are getting what they need. Vitamin C in water breaks down and may alter the water's taste, discouraging pets from drinking it, so this form of vitamin C is not recommended. If you ever notice anything out of the ordinary with your guinea pig, take them to their veterinarian right away. Signs of possible illness include sneezing, crusty eyes, weight loss, decreased appetite, decreased stool production, lethargy, hair loss, and diarrhea. With proper care, guinea pigs can live up to eight or nine years. Like any other pet, your guinea pig should get annual check-ups so your veterinarian can detect problems earlier and begin any necessary treatment sooner. Consult with your veterinarian to ensure that your guinea pig is getting the proper nutrition they need.