Non-guinea pig owners will never understand how demanding these itty-bitty rodents can be about their diet. Not only do they squeal about every hour for more snacks, but they are also very sensitive to a variety of foods and plants. For example, guinea pigs cannot eat onions. In fact, onions are one of the most poisonous foods for guinea pigs, despite how loved they are by humans.
In other words, onions are one of the worst foods you can feed a guinea pig. To find out more about why guinea pigs can’t eat onions and the risks associated with this vegetable, keep reading. In this article, we’ll tell you exactly why guinea pigs can’t eat onions, associated risks, better onion alternatives, and much more.
Let’s get started.
Can Guinea Pigs Eat Onions?
Guinea pigs cannot eat onions. Even a small amount of onion can poison and kill guinea pigs, making onions one of the most poisonous vegetables available. Although guinea pigs are not technically allergic to onions, onion compounds are highly toxic.
No matter how the onion is prepared, you should not feed it to your piggy. This includes raw onions, cooked onions, onion skins, and the fleshy part of the onions. This also includes foods related to or including onions, such as shallots or onion rings.

Why Are Onions Bad For Guinea Pigs?
Onions are bad for guinea pigs because of two main ingredients. They are made up of thiosulphate and disulfide compounds. Both of these compounds are highly toxic for guinea pigs, as well as many other animals people keep as pets.
Thiosulphate is a chemical compound that contains hydrogen, oxygen, and sulfur. Disulfide compounds have a special bond and is often found in foo proteins. Both of these ingredients are incredibly toxic to guinea pigs, dogs, and other animals.
Although these two compounds are the most dangerous in onions, onions have a number of other harmful ingredients to guinea pigs. For example, they have way more sugar and calcium than guinea pigs should eat, resulting in sugar and calcium overload.
Whenever guinea pigs consume onions and other foods with these ingredients, they will have a number of complications, such as urinary issues, digestive troubles, anemia, and even death if the issue is left untreated.
Risks Associated With Onions
Even feeding your guinea pig a little bit of onion can lead to really serious health issues. Whenever your guinea pig first consumes onions, their eyes and nose will typically run. In most cases, the guinea pig will salivate more too. Because of how small guinea pigs are, it can be difficult to notice discharge and increased salivation.
One of the most obvious signs that your guinea pig has consumed onions is that they vomit. Vomiting is not something normal in guinea pigs. They’re not like dogs, cats, or humans who can vomit without any serious repercussions.
- Urinary Difficulties
Guinea pigs do not require a lot of calcium, and onions contain quite a bit of it. If guinea pigs eat enough onion, they will ingest way too much calcium, causing urinary problems, like bladder and urinary tract stones. Although urinary difficulties are not necessary life threatening, they are extremely painful for your guinea pig.
- Digestive Issues
As you probably know already, guinea pigs have very sensitive digestive systems. For one, guinea pigs cannot eat too much sugar. Although onions do not taste sweet, they have way more sugar than guinea pigs should consume. Excessive sugar intake leads to severe digestive issues, as well as other health issues like blood sugar levels.
- Anemia
One of the more serious side effects of onions is the potential to cause anemia. The disulfides within onions cause damage to guinea pig red blood cells, which leads to respiratory issues and anemia. More so, the disulfides can also lead to respiratory troubles along with the anemia.
- Death
If you do not treat your guinea pig or continue to feed them onions, onion consumption can be fatal. To ensure that your guinea pig is safe, we recommend taking them to a veterinarian as soon as you think they consumed onions, even if it was only a little bit.

Benefits of Feeding Onions to Your Guinea Pig
Onions cannot be all bad for your guinea pig, right? Right. There are a few benefits of onions that are theoretically healthy for guinea pigs, though the negative health consequences dramatically overshine the positive ones.
For example, onions have quite a bit of vitamin C. Guinea pigs do not naturally create vitamin C like rabbits, meaning that you must supplement vitamin C into their diet. Illnesses like scurvy are common in guinea pigs because of their lack of vitamin C.
Even though onions have a lot of vitamin C, you should not feed them to your cavies. There are tons of healthier fruits and vegetables that can help your guinea pigs load up on vitamin C without exposing them to disulfides, excess sugar, or excess calcium.
Better Onion Alternatives
If you are looking for a better way to feed your guinea pig vitamin C, you’ll be happy to know that there are a lot of options. Blueberries, green peppers, and strawberries are some of the best natural sources of vitamin C.
We prefer to feed our guinea pigs green peppers simply because strawberries and blueberries are higher in sugar. These fruits are great options as the occasional treat. The piggies absolutely go crazy whenever they get fed any of these snacks.
You can also buy your guinea pigs vitamin C fortified pellets. Most guinea pig pellet mixes include vitamin C. However, you must be sure to select a guinea pig pellet mix, not a rabbit pellet mix. Though the two mixes look really similar, rabbits do not need vitamin C like guinea pigs, causing rabbit pellets to lack this crucial nutrient.
We prefer buying vitamin C spray and spritzing it over our guinea pig’s vegetables every other day. This is a much more economic choice because it lasts longer than pellets. It doesn’t seem to have any effect on the flavor of the lettuce or vegetables. Our guinea pigs devour their food either way. The only downside is that the spray has an unpleasant odor.
If your guinea pig overeats on the pellets, vitamin C spray is a better option. Our piggle wiggle Gumbo would not stop eating pellets, which caused him to gain weight really quickly. When we switched to the spray, Gumbo went back down to his natural weight.
There are other vitamin C supplements you can try, such as vitamin C water drops.
What To Do If Your Guinea Pig Eats An Onion
Because even the smallest amount of onion can cause severe harm to a guinea pig, it’s important to act fast if you suspect your piggy consumed even a little bit of onion. The first thing you should do is pay attention to the most immediate signs, such as discharge, increase elevation, and vomiting.
Even though it is important to watch for these signs, onion consumption is not something you should wait out. If you know your guinea pig consumed onions, call your veterinarian immediately. As soon as the first symptoms show up, your guinea pig’s health can deteriorate quickly.
Unfortunately, onion poisoning is not something you can treat yourself. You need to take your guinea pig to a reputable and trustworthy exotic pet veterinarian. They will do everything in their power to give your pet the best possible chance of survival.

Prevention Tips
Guinea pigs are not like dogs or cat. They can’t jump on your counter and steal onions when you aren’t looking. Because of this fact, it is rather easy to prevent guinea pigs from eating onions. It’s important to integrate prevention tips into your home to ensure your guinea pigs remain healthy and happy.
For indoor onions, make sure to store them someplace where your guinea pig can’t reach them. Somewhere on a shelf would be the ideal option since guineapigs can’t reach that high. Additionally, make sure to sweep up and wipe down the floor if you drop any onions or onion peels while cooking.
If you grow onions outside, make sure that the onions are grown somewhere that your guinea pig cannot get to during their outdoor time. Adding a short barrier can prevent your guinea pig from eating onions.
Final Thoughts
Once again, you cannot feed onions to guinea pigs. Onions are incredibly toxic and often lead to death. If you suspect that your guinea pig has ingested any onions, call your veterinarian right away. To prevent onion poisoning in your guinea pig, incorporate the easy-to-follow prevention tips into your home and garden.

The main author of Vivo Tail, Stefan is .NET desktop application developer since 2016, content writer and above all – passionate animal lover. He decided to start a website to help animals in need after the dog he loved has passed away.