Can Guinea Pigs Eat Onions From the Garden? (Explained)

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Fresh onions straight from the garden are a great addition to a variety of meals. Since guinea pigs are herbivores, most of you might think that you can serve any vegetable to your pet.

If that’s the case, can guinea pigs eat onions from the garden? 

No, guinea pigs cannot eat onions. In fact, onions are considered to be the most poisonous vegetables for guinea pigs.

Feeding even small amounts of onions, as little as 7g, occasionally to guinea pigs can damage their body or cause death.

Now that you know that guinea pigs cannot eat onions, is it because guinea pigs are allergic to onions?

Let’s find out!

Are Guinea Pigs Allergic to Onions?

A picture of onions as an allergic food for guinea pigs

No, guinea pigs are not allergic to onions. Instead, onions are toxic for guinea pigs as they contain compounds called disulfide and thiosulphate.

Feeding onions to guinea pigs can cause their death much before they could develop any allergies. 

If feeding onions doesn’t cause the immediate death of guinea pigs, they are likely to develop major health issues in no time.

Serving onions to guinea pigs can make them sick and develop symptoms like:

  • loss of appetite
  • increased salivation
  • watery eyes
  • pale skin
  • and diseases like anemia

Let’s discuss the risks in feeling onions to guinea pigs in detail in the next section.

Risk in Feeding Guinea Pigs Onions

There are many risks in feeding onions to guinea pigs. Let’s have a look at some major health risks of feeding onions to guinea pigs.


Guinea pigs can die by eating onions. Onions can lower the oxygen supply in guinea pigs, suffocating them to death. 


The disulfides present in onions can damage the red blood cells of guinea pigs. The damage caused to the red blood cells results in the lack of hemoglobin in guinea pigs leading to a disease called anemia.

In some cases, the damage caused to the red blood cells makes oxygen transfer to different organs difficult, resulting in the death of guinea pigs. 

Urinary Infection

The rich calcium content of onions can result in urinary infections in guinea pigs.

Besides urinary infections, onions can also result in the formation of bladder stones in guinea pigs. Bladder stones are painful, and in most cases, they can be removed by surgery. 

Irritation in Eyes

Onions can cause irritation in the eyes of guinea pigs because of the presence of a compound called syn-propanethial-S-oxide.

The irritation caused due to this compound might further lead to watery eyes, a runny nose, and increased salivation in guinea pigs. 


The rich sugar content (7g per 160g) of onions might result in diabetes in guinea pigs. Diabetes can lead to weight gain and kidney failure in guinea pigs.

If not treated timely, you may also lose your pet. 

Breathing Issues 

Guinea pigs can experience breathing problems on eating onions. As discussed earlier, onions contain disulfides which are poisonous to guinea pigs.

The high presence of disulfides stops the proper flow of oxygen in guinea pigs, making it difficult for them to breathe.

Besides the risks discussed above, you may notice signs like loss of appetite, paleness, weakness, and cold in guinea pigs that are served onions. 


The rich fiber content of onion might lead to diarrhea in guinea pigs. Diarrhea results in watery stool and stomach ache in guinea pigs. 

We have discussed many risks of feeding onions to guinea pigs. But are there any benefits of onions to guinea pigs too? Let’s find out!

Benefits of Onion to Guinea Pigs

There are no benefits to feeding onions to guinea pigs.

It might appear that feeding onions might prevent scurvy in guinea pigs because they are rich in Vitamin C. However, it’s not true as onions are poisonous to guinea pigs.

According to research, feeding vegetables of the Allium family like garlic, onion, shallot, and chives is dangerous for animals like cats, dogs, and guinea pigs.

Feeding onions to these animals can lead to onion poisoning. The common symptoms of onion poisoning are vomiting, diarrhea and stomach ache. 

Onion Alternatives

Below are some onion alternatives that you can consider serving to your guinea pigs. 

Green BeansTomatoesDandelionsGreen Turnips
Bell PeppersZucchiniCornTomatoes


Can Guinea Pigs Eat Green Onions?

No, guinea pigs cannot eat green onions. The bulb of green onions is toxic for guinea pigs.

However, you can try feeding the leafy part once a week to your guinea pigs as it contains nutrients good for your cavy’s health. 

Can Guinea Pigs Eat Red Onions?

A picture of red onions not as a food for guinea pigs

No, guinea pigs cannot eat red onions. Just like other types of onions, red onions are also poisonous for guinea pigs as they contain disulfide.

Besides disulfides, red onions are also rich in calcium and phosphorus, the nutrients bad for the health of a guinea pig. 

Can Guinea Pigs Eat Spring Onions?

A picture of spring onions not as a food for guinea pigs

No, guinea pigs cannot eat spring onions. Aka scallions or green onions, spring onions are toxic for guinea pigs.

Apart from being toxic, they are also highly acidic and have high water content. 

As a result, feeding spring onions can lead to stomach infections, digestive problems, and diarrhea in guinea pigs. 

Can Guinea Pigs Eat Spring Onion Tops?

A picture of spring onion tops as a food for guinea pigs
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Yes, you can feed spring onion tops to guinea pigs. Spring onion tops are basically green leaves. You can feed it to your guinea pigs in small quantities preferably once or twice a month.

Serving the right quantity of spring onion tops will keep your pets healthy. 

Can Guinea Pigs Eat Onion Grass?

No, guinea pigs cannot eat onion grass. Just like onions, onion grass also belongs to the allium family. Feeding any vegetables from the allium family is dangerous for guinea pigs.

According to tp RSPCA, both onions and onion grass are mentioned in the list of vegetables that you should avoid giving to guinea pigs. 

Can Guinea Pigs Eat Onion Leaves?

Yes, guinea pigs can eat the leafy part of spring onions in limited quantities but that’s it. No other variety of onion leaves should be given to guinea pigs.

In fact, onion seeds and peels are also unhealthy for your cavies and you should avoid feeding them to your pets. 

Can Guinea Pigs Eat Dried Onions?

No, guinea pigs cannot eat onion in any form be it raw, cooked, or dried. Onion in any form is equally toxic for your guinea pigs as it contains disulfide.

Even a little bit of onion can prove to be deadly for your little pets. 

Final Thoughts

In this article, we have learned that onions are poisonous for guinea pigs, mainly because they contain disulfides that are dangerous for guinea pigs.

Serving even small amounts of guinea pigs can damage their red blood cells and kill them.

Your pets might also suffer from eye irritation, diarrhea, bladder stones, breathing issues, and weakness as a result of eating onions. 

You can consider feeding them onion alternatives like kale, broccoli, corn, cabbage, and spinach. But avoid serving them any vegetable of the allium family. 

Feel free to share this article if you find it helpful! 

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