Can Guinea Pigs Eat Onions?

The onions are the well known aromatic veggie that brings a magnificent flavor to any salad or cooked meal. Its scent might make us ‘cry’ while we chop it, but the health benefits of onions are numerous! However, even though this is a vegetable, and our guinea pigs are vegetarians, we must check if they can eat onions.

Can guinea pigs eat onions? No, guinea pigs cannot eat onions. In fact, the onions are toxic for the guinea pig because they contain a compound called disulfide which is unhealthy for the guinea pigs. This compound can cause eye irritation, excess salivation, nasal secretions, and even respiratory problems too. Apart from these, another possible problem is damage to the red blood cells in the blood of the guinea pig. When the blood cells are damaged in any way, they transfer less oxygen throughout the whole body – hence there is risks of anemia, fatigue, bad immunity and again, the breathing problems!

So, we have seen that the onions are not good at all for the guinea pigs. At first, we would think that the odor or aroma would be just too much to handle for the gentle stomach of the guinea pigs. But, it seems there are more complications coming from onions that are very serious for the guinea pigs. However, in the coming sections will discuss the onion nutrients, also we will mention the nutritional facts for onions, as well as the risks for the guinea pigs.

Health Benefits of Guinea Pigs Eating Onions

Sadly, the only benefit from onions for guinea pigs is vitamin C. However, since they cannot consume the onions, they can’t get vitamin C from this vegetable. Consuming onions makes very serious problems for the guinea pigs, not just the typical urinary issues they could get from most foods. There will be complications of internal and external organs, and also the aroma and taste of onions itself is very strong for their fragile stomachs. See more about the risks in the sections below.

Nutrition Facts of Onions

These are the nutrients in 100g (3 oz) of onion:

  • Relatively low in calories – the onion is not very caloric so it has just 40 calories per 100 g. This caloric amount is not bad for maintaining a healthy weight in general.


  • Carbs and proteins – there are 9.3 g of carbs and 1.1 g of protein. These two give energy and warmth for the whole day ahead. These amounts might not be much, but they are enough considering this is a vegetable.


  • Fiber – 1.7 g. Onions have a bit of fiber too, which is an essential compound for good digestion and healthy bowel movements.


  • Sugar – 4.2 g. This amount of sugar is not good for the guinea pig because it will cause bad digestion and stomach pains. But, of course, cavies cannot eat onions in the first place, so this shouldn’t worry you anyway.


  • Low in fat and no cholesterol – 0.1 g fat and also zero cholesterol. The low-fat amount won’t affect weight in any way, and also together with the zero cholesterol, this contributes to healthy and unclogged blood vessels. So, the whole cardiovascular system works well because of these amounts of fat and cholesterol.


  • Vitamin C – 12 %. The vitamin C is essential for everyone’s health. Mostly, it is vital for repairing the body tissues, internal as well as external ones. Also, it forms collagen which is crucial for tissues in the body and healthy skin too. This vitamin also speeds up the healing of wounds and makes immunity stronger. For guinea pigs, it keeps them safe from scurvy, but sadly they can’t receive this vitamin from an onion because they can’t consume it.


  • Vitamin B6 – 6 %. This vitamin is good for proper growth and development of fetuses, especially for good brain development. Also, B6 creates the happy hormone serotonin that reduces stress and anxiety but also helps with better sleep.


  • Calcium – 23 mg. This amount of calcium is too much for guinea pigs if we consider they could eat onions, which isn’t the case. Too much calcium creates many urinary problems in guinea pigs.


  • Potassium – 146 mg. This compound regulates the blood pressure and balances the water and electrolytes (salts) in the body, overall this makes the cardiovascular system much healthier.

Risks to Consider When Feeding Onions to Guinea Pigs

  • Urinary problems – If the guinea pigs could consume onions, they would cause great damage to their urinary system. This is because onion has calcium, and when calcium piles up in their kidneys, there is a risk from urinary stones which make painful urination. Also, there will be a risk of blood in the urine or urinary infections and all this can be fatal for the poor little guinea pig!


  • Digestion problems – The onion contains fibers and sugar. If the guinea pig consumes too much fiber, or excess of sugar together with the fiber, it will have painful digestion, loose stool, and similar gastrointestinal complications.


  • Other serious complications – We mentioned above that onions contain the compound disulfide. This will affect mostly the respiratory system of the guinea pigs. The disulfide damages red blood cells – the main carriers of oxygen in the body. So, when the organism doesn’t get enough oxygen from head to toe, the breathing is the first and most serious problem noticed. The consequences of lack of oxygen will also result in bad health of the blood (because of damaged red blood cells) that can later develop anemia. When anemia is diagnosed the symptoms are loss of appetite, weight loss, paleness, fatigue, and feeling cold all the time. Other complications due to disulfide are secretion from the nose, irritation of the eyes, as well as increased salivation in guinea pigs.

Quick Facts on Onions

  • Onions have been consumed by people for more than 7,000 years, and first traces of onions were found to date back to 5000 B.C.
  • The ancient Egyptians liked onions a lot and even worshipped them. They believed the shape of onion and its many layers inside signify eternity. They used to put them on pharaohs’ tombs for good afterlife.
  • Onions were once considered a currency! Back in the Middle Ages, when someone didn’t have money for rent, he would offer onions instead. They were also given as gifts too!
  • We ‘cry’ when we cut the onions because they contain the sulfuric acid (hence irritation in guinea pig’s eyes too!)
  • The largest grown onion in the world was found in the UK, and it holds the record of an amazing 18 pounds!
  • The onions are a natural remedy for skin issues, such as bug bites or burns.

Related Questions

Onions have many good nutrients, one of them is vitamin C. But, how to substitute onion with another vegetable to give my cavy his vitamin C?

You don’t have to risk your guinea pig’s health to give him vitamin C from an onion! So instead, feed him broccoli, cauliflower, bell peppers, leafy greens, zucchini, and squash too. There are many foods with vitamin C that your guinea pig can eat safely!

So, guinea pigs cannot eat onion. But, can they at least try garlic to receive the similar benefits onion has?

No! Guinea pigs cannot consume garlic either, because this veggie contains oxalic acid. This compound could cause allergy for the guinea pig. Also, garlic is a bulb veggie and guinea pigs can’t eat these veggies. Plus, garlic has an even stronger aroma and taste than onion, so this would certainly accentuate digestion problems and stomach pains too!

Before I let you go, one final thought on food. With food, you can’t ever be too careful which is why I get all guinea pig food from a reliable source such as Amazon. If you are not sure what to order but believe your little piggies deserve some great treats please check our Helpful Guide to the Best Guinea Pig Treats to get some ideas. We have also made a full list of foods that guinea pigs can and can’t eat (150+ Types of Foods). Be sure to also check our recommended products page for everything you will ever need to assure a happy life for your Guinea Pigs. Hope this information was helpful and you have found the answer you were looking for.

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