10 Major Side Effects of Eating Too Many Onions

Onion or bulb onion is a popular vegetable that belongs to the genus Allium. They have been cultivated in many regions of the world for centuries, and are available in different varieties like Red Onion, yellow onion, and green onion.

Nutrients like vitamins, minerals, antioxidants, and dietary fibers, etc in onions provide amazing health and beauty benefits. However, in excessive quantities, onions may cause side effects and health problems.

Side Effects of Eating Too Many Onions

Following are some of the common side effects of eating too many onions.

Side Effects of Eating Too Many Onions


(1) Not Safe For Individuals Who Are Allergic To Onions

Onion can be consumed regularly due to the abundance of nutrients that provides tremendous health and beauty benefits. But, if you are allergic to onions then you should stay away from them as it could give rise to allergic symptoms like redness of skin and eyes, itchy skin, breathing difficulty, oral swelling, and tingling.

Excessive intake of onions may drop our blood pressure to an abnormally low level that requires immediate medical attention.

(2) May Cause Intestinal Gas And Abdominal Bloating

Natural sugar like fructose in the onion is known to produce gas in our stomach. In small quantities, this isn’t a problem. However, when onions are consumed in excess, the build-up of excessive gas may lead to abdominal bloating, stomach discomfort and in increased flatulence, etc.

This is due to the poor efficiency of our digestive system to digest sugars. Excess sugars enter the intestines and are broken down by bacteria. During this process, gas is formed.

If your digestive system is intolerant to onions, then you may also experience nausea, vomiting, and diarrhea.

(3) May Cause Heartburn

Consuming onions regularly strengthens our cardiovascular system and keeps our heart healthy. However, in excessive quantities, this may lead to digestive problems like heartburn (a burning sensation and extreme pain in the chest).

As per a 1990 study published in the “American Journal of Gastroenterology ”,  people who over-consume onions are more likely to experience digestive problems like heartburn, and pregnant women are at even higher risk.

To stay safe, eat onions in moderation, and in case of pregnancy, consume onions only after consulting with your doctor.

(4) May Interfere With Certain Medications

Vitamin K, a natural blood-clotting agent in the onions (especially green onions) interferes with the functionality of blood-thinning medications like warfarin and coumadin, etc.

So, if you are on blood-thinning medications then consume onions after having a word with your doctor.

(5) Too Much Potassium Is Bad For Our Health

Onion contains potassium, a vital mineral, and a natural vasodilator that relaxes our blood vessels improves blood circulation and provides relief from hypertension or high blood pressure. It also improves cardiovascular health.

However, eating too many onions may increase potassium levels in our bodies. High levels of potassium in our body may drop our blood pressure to an abnormally low level thereby increasing the risk of hypotension. Some common symptoms of hypotension are dizziness, lightheadedness, blurred vision, nausea, and fatigue, etc.

Also, potassium in the onion could interfere with medication meant for regulating hypotension. So, if you are taking medication for regulating blood pressure levels, then consume onions in moderation and only after a doctor’s consultation.

(6) May Cause Skin Irritation In Some Individuals

Because of its antiseptic properties, onion juice is being used for treating skin bruises, wounds, and pimples, etc.

However, these benefits can’t be enjoyed by those who are allergic to onions or have sensitive skin towards onions.

These individuals should avoid (consumption as well as the topical application) onion or onion juice completely to avoid the risk of allergic reactions like skin itching, irritation, and redness of the skin, etc.

Do a patch test before using onion or onion juice on the skin.

(7) May Cause Bad Breath And Strong After Smell

Onions contain sulfur that provides several benefits like cell detoxification, aids insulin production, makes arteries and veins flexible. However, it also causes bad breath and a strong after smell. 

To avoid this issue, eat Onion in moderation.

If the smell is too strong, you can chew some pieces of cardamom to mask the smell.

(8) May Worsen Cardiovascular Problems

Vitamins, minerals, antioxidants, phytonutrients, and polyphenols, etc in onions improve cardiovascular health and keep our heart healthy.

Potassium in it provides relief from hypertension, a silent killer and a leading cause of various cardiovascular problems like heart stroke, heart attack, and coronary artery disease.

However, too much potassium may drop the blood pressure to an abnormally low level giving rise to hypotension and other cardiovascular complications like irregular heartbeat and heart stroke, etc.

Eat onions in moderation to eliminate the risk.

(9) May Lowers Blood Sugar To Dangerously Low Level

With a low glycemic index of 10, onions slowly release sugar into the bloodstream and thus helps in managing diabetes.

The chromium in onions slows down the absorption of sugar by the bloodstream, and thus regulates blood sugar levels.

However, overeating onions may drop blood sugar to an extremely low level thereby increasing the risk of hypoglycemia with symptoms such as excess sweating, excessive hunger, fainting, fatigue, nausea, vomiting, blurred vision, anxiety, palpitations, and sensation of pins and needles, etc.

Also, if you are on diabetes medication then you should consume onions as per the doctor’s recommendation to avoid possible food-drug interference.

(10) Too Much Fiber is Bad

The laxative properties of the dietary fibers in onions relieve constipation and other gastrointestinal issues like abdominal pain, bloating, irritable bowel syndrome, gas, and flatulence, etc.

Dietary fibers also help with detoxification, regulates blood sugar, manages cholesterol level, improves cardiovascular health and promotes weight loss, etc.

However, in large quantities, dietary fibers may cause poor absorption of nutrients, and digestive issues cramping, diarrhea, malabsorption, constipation, intestinal gas, abdominal bloating, intestinal blockage, etc.

Consume onions in moderation to avoid such risk.


The information contained in the post is for general purposes only and shouldn’t be considered as medical advice or as an alternative to medical advice. Although I’ve tried my best to keep the information contained in this post as accurate and updated as possible, I make no guarantee of the accurateness of the same.

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