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Can Guinea Pigs Eat Onions? Vet-Reviewed Nutrition Facts & FAQ

Jeff Weishaupt

By Jeff Weishaupt


Vet approved

Dr. Amanda Charles Photo

Reviewed & Fact-Checked By

Dr. Amanda Charles

Veterinarian, BVSc GPCert (Derm) MRCVS

The information is current and up-to-date in accordance with the latest veterinarian research.

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As an herbivore, your guinea pig might love munching vegetables all day and night. But as a responsible cavy parent, you must know which veggies are safe for them. While these adorable pets like almost every vegetable, you shouldn’t feed them onions—not even in small quantities.

Onions are toxic for guinea pigs. Even if your pet takes a small bite, it will put them at a severe health risk.

So, if your guinea pig accidentally consumes onions, you should seek immediate medical help for them. A professional vet will try to save your pet’s life, but it can be difficult for these little animals to recover from the damage done.

This post discusses everything you should know about your pet eating onions. So, keep reading till the end.

Divider Guinea Pig

Are Onions Poisonous to Guinea Pigs?

Many pet owners believe their guinea pig is allergic to onions. But in reality, this vegetable is toxic for them. It contains disulfide and thiosulphate, which can make your little pet very sick or even cause their death.

Eating onions doesn’t result in instant death. Instead, it will first make your guinea pig unwell with severe medical issues, deteriorating their health and even eventually causing death.

Some common signs your guinea pig has eaten onions include the following:
  • Teary eyes
  • Excessive salivation
  • Diarrhea
  • Sudden appetite changes
  • Pale skin

Are All Types of Onions Toxic for Guinea Pigs?

Even if your garden has different types of onions, you still can’t feed any of them to your guinea pig. Whether green, red, or white, they all are toxic for your little pet. Here is why:

Green Onions

Green onions consist of a white bulb on top with green leaves below. The bulb is toxic for your guinea pig, but you can feed them the green leafy part occasionally.

Red Onions

Guinea pigs cannot eat red onions. They are toxic in the same way as regular onions.

sliced red onion
Image Credit: costanzimarco, Pixabay

Spring Onions

Spring onions or scallions are also toxic for guinea pigs as well as being super acidic.

Onion Tops

Onion tops are similar to green leaves, which these little animals enjoy. So, yes, you can feed them a small amount of onion tops. However, keep their quantity limited to once or twice a month.

Onion Grass

Like onions, onion grass also belongs to the same Allium family, making it equally toxic for your guinea pet. In fact, any veggie from this family is considered poisonous for cavies. So, don’t include the onion grass in your pet’s diet.

Dried Onions

Onions in any form and type are bad for guinea pigs’ health. Whether you dry or cook them, they remain toxic.

As a safety measure, we recommend keeping your cavy away from all types, forms, and parts of onions. There is no point in risking your adorable pet’s life with so many other healthy vegetables readily available.

dried onions in wooden scooper with whole onion
Image Credit: Narsil, Shutterstock

Health Risks of Feeding Onions to Guinea Pigs

As you know, onions don’t cause instant death in guinea pigs. Instead, they first put your pet at a severe health risk, leading to their death. Here are some health issues onions can cause in guinea pigs:

Eye Irritation

This may be one of the first signs you see as onions contain an irritant called syn-propanethial-S-oxide, which triggers tearing and irritation in the eyes. When guinea pigs come in contact with it, they experience watery eyes and runny noses. Some pets also show excessive salivation.

Digestive issues

The high sugar and acidity of onions may also lead to digestive problems such as diarrhea, abdominal pain and lack of appetite.


When your guinea pig eats onion, it’s disulfide that targets the red blood cells and leads to their destruction and anemia. Anemia means the guinea pig’s body does not get enough oxygen-rich blood and can even be fatal.

veterinary doctor holding guinea pig on hands
Image Credit: Tatyana Vyc, Shutterstock

Breathing Difficulties

The toxins in onions can also lead to breathing issues in guinea pigs. Since they cause anemia and reduce oxygen transport in your pet’s body, they can start to show signs of breathing difficulties, as well as an increased heart rate.


That’s sadly the eventual consequence of eating onions for your guinea pig.

Avoiding all these risks is pretty simple; don’t feed onions to your guinea pigs.

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The 4 Steps If Your Guinea Pig Eats Onions

Since guinea pigs are active pets, it’s hard to monitor their every activity throughout the day. So, what if they take a small bite of onion when you’re not around? No less than a nightmare!

It’s understandable to panic at this moment, but that will increase the risks for your pet even more. As an aware guinea pig owner, you must think practically and implement an action plan to counter this mishap.

Here is what you should do if your guinea pig eats onions:

1. Remove the Onion

The first thing you should do is remove the onion from your guinea pig’s range. This will stop your pet from taking another bite of the poison.

Since it won’t cause instant side effects in the animal, they may still be running around the house as if nothing happened. So, put them in their home or enclosure to think about your next steps with a clear mind.

owner petting his guinea pig inside its travel cage
Image Credit: Chewy

2. Contact a Medical Professional

Next, reach out to an expert. If you already have a vet, ring them immediately to seek timely help. Otherwise, you can search on the internet for local vets in your area. It’s recommended to keep the vet’s address and number on hand for easy access.

3. Take Your Guinea Pig to the Vet

The vet will ask you to bring the guinea pig to the clinic as soon as possible. It’s better to carry your pet in a cage,box or enclosure to ensure their safety. But if you don’t have one, wrap the cavy in a soft, clean towel and take them to the clinic.

4. Follow the Vet’s Instructions

If you and your pet are lucky, the vet will be able to save them with appropriate medications and treatments. They will also give you a list of instructions to follow at home. Make sure to implement them properly to restore your guinea pig’s health and prevent them from developing severe medical issues

guinea pig in the hands of a veterinarian in a blue uniform with a phonendoscope around her neck
Image Credit: Garna Zarina, Shutterstock

The Best Alternatives to Onions

Onions are poisonous to guinea pigs. There is no doubt about that. So, it’s better to avoid feeding anything related to onions to your pet for their own safety.

Guinea pigs love vegetables, there are many veggies available that they can safely enjoy including:

guinea pig eating basil
Image Credit: TJ Images, Shutterstock

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Guinea pigs love vegetables, but they should stay miles away from onions. That’s because they are toxic to them and can cause serious issues including anemia and even death.

However, you may be able to save your pet with on-time medical care. So, instead of panicking, seek help from your vet as soon as possible if your guinea pig has accidentally consumed some onion.

Featured Image Credit: rotozld, Pixabay

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