8 Foods That Guinea Pigs Shouldn’t Eat

Since chewing is pretty much a guinea pig’s favourite past-time, these little guys would be able to eat their way through anything. And while there’s a lot on the menu that they can eat, there are a few dishes that should be completely avoided.

If you’re ever in doubt, it’s a good idea to think about whether the food is in the guinea pig’s natural habitat and is it something they’d be able to just find. For example, guinea pigs are more likely to eat leafy greens and grass rather than buried bulb vegetables, seeds and dairy.

We also have an in-depth guinea pig care guide in case you’re unsure about any other aspects of caring for your domestic cavy.

The foods your guinea pig should avoid

Since we understand that food in their natural environment is not always clear cut, below are the foods to definitely avoid.

1. Dairy

Guinea pigs are herbivores, so basically eat a vegan diet. Their teeth or digestive enzymes cannot break down these foods, and this can lead to severe digestive issues. A definite no, with no exceptions.

2. Cereal, Seeds, Oats

It’s advised not to give guinea pigs cereal because they often contain sugar. Even if they are marketed as low in sugar, seeds and grains are generally not good for guinea pigs simply because it leads to weight gain and dental difficulties. There’s also a risk that piggies can choke on larger seeds.

While oats are healthy for humans, they’re not too great for our little friends since they contain a lot of phosphorus that can damage their urinary systems. Oats are also full of carbohydrates which isn’t ideal for little piggies.

Another thing to avoid is the seeds and stones of fruits such as apples, peaches and cherries. Many contain cyanide, which can cause heart and nervous system failure.

3. Nightshades

We imagine you’ve already heard of the infamous nightshade family. The difference between nightshades and regular vegetables is that nightshades have levels of solanine in them, which is poisonous to guinea pigs and can cause fits, seizures and heart failure – pretty serious stuff, we know.

Not all nightshades are bad for guinea pigs, but those which definitely are include:

  • Potatoes
  • Aubergine
  • Goji berries
  • Blueberries

Tomatoes are a nightshade, but their skins are safe in small doses and a great source of vitamin C. It is the stems and leaves you need to avoid.

The same applies to peppers. They’re safe, but remove the seeds due to bitterness and choking hazards.

4. Avocados

Various other vegetables are harmful to guinea pigs too, including avocados, which are not ideal because of the fat content alone.

Additionally, they also contain persin, which is harmful to a lot of pets and can lead to vomiting, diarrhoea and shortness of breath. Something for pretty much all pets to avoid, so when you’re mashing it for your toast, ensure they can’t access it.

5. Bulb Allium Vegetables

Bulb allium vegetables, including onions, leeks, chives and garlic, are also incredibly toxic to guinea pigs since it’s difficult for them to digest. They also contain thiosulfate, which can cause haemolytic anaemia, damaging red blood cells and negatively affect their breathing.

Most guinea pigs are instinctively wary of these foods, so won’t go near them. But it isn’t worth taking a risk. Again though, all pets should be avoiding these, so also think about whether they are ingredients in any other foods.

6. Iceberg Lettuce

Surprising we know, but iceberg lettuce isn’t all that great for guinea pigs. While it is technically safe for them to eat, since it’s high in water it can cause bloating and diarrhoea, which may lead to dehydration. It is also very high in calcium and too much of this is bad for piggies since it can lead to kidney stones.

Iceberg is also low in vitamin C, which is a vital component in a healthy guinea pig diet, so it is wasted calories on them.

You can still feed your guinea pig small amounts of lettuce, but romaine lettuce is better as a treat because it has less calcium and more vitamin C, making it a much healthier option.

7. Beans

The majority of beans are incredibly gassy and so can cause discomfort for your piggies. If you’re looking to switch up your piggies diet, consider green beans as a treat now and again.

Green beans contain calcium, which isn’t good for piggies in large amounts, but they are rich in vitamin C, so giving green beans as an occasional treat will be fine.

8. Rhubarb

Rhubarb has many toxins in it; it’s too high in calcium, contains phosphorus, and is high in oxalic acid, which reduces mineral absorption and can lead to kidney stones. For this reason, it’s really not a good idea to feed your guinea pig rhubarb.

two guinea pigs eating guinea pig pellet food from a yellow bowl
Commercial pellets are available for pet guinea pigs 

So – what can my guinea pig eat?

There are foods made especially for guinea pigs kept as pets.

A key element of their diet is good quality hay, such as Timothy hay. A vital part of their diet, hay contains fibre for good digestion. For this reason, it should be available at all times.

Did you know? A guinea pig’s teeth also grow continuously, so they need to chew on hay to grind them down

Commercial guinea pig food is specially made to include all of the nutrients and goodness your piggy requires. The food should be in pellet form, and approved by vets, from a trusted manufacturer.

Vegetables should be limited to one cup per day. Introduce new foods one by one. Ideally, look for great quality organic greens such as:

  • Romaine lettuce
  • Carrots and tops
  • Peas
  • Broccoli spears
  • Cucumber
  • Spinach
  • Kale
  • Tomatoes (without green parts or stems)
  • Green and red peppers

Small, bite-sized pieces of fruit can also be given daily. Never give them much, as they are high in sugar. But they make a great treat. Safe fruits include:

  • Oranges
  • Apples
  • Pears
  • Strawberries
  • Blueberries
  • Kiwi