Doctors Speak Frankly: Four Types of People Should Avoid Onions

Onions are generally considered healthy, but they are not suitable for everyone.

Onions are a familiar food that offers many health benefits when used properly. They are rich in antioxidants, especially quercetin, which helps reduce inflammation, strengthen the immune system, prevent colds and flu, and support the prevention of certain diseases.

Onions are also beneficial for cardiovascular health thanks to their ability to help lower bad cholesterol and improve blood circulation. The sulfur compounds in onions can help regulate blood sugar levels, making them useful for people who need to maintain stable blood glucose.

In addition, onions support gut health, are rich in vitamin C, help improve skin appearance, and boost immunity.

However, despite their benefits, onions are not suitable for everyone. The following groups should limit or avoid eating onions:

People with stomach disorders or acid reflux
Onions are pungent and contain sulfur compounds that can irritate the stomach lining. Therefore, people experiencing acute stomach pain, gastric ulcers, or gastroesophageal reflux disease (GERD) should avoid onions, as they may worsen burning sensations, pain, and reflux symptoms.

People with weak digestion or frequent bloating
Onions contain fructans, a type of hard-to-digest carbohydrate. People who are prone to bloating, gas, digestive disorders, or irritable bowel syndrome (IBS) may experience indigestion, abdominal pain, or discomfort after eating onions—especially raw onions.

People with diarrhea
Because onions stimulate digestion and have a pungent nature, they can aggravate diarrhea. If you are experiencing diarrhea or intestinal irritation, it is best to avoid onions until your condition improves.

People allergic or sensitive to onions
Although rare, some people are allergic to onions. Symptoms may include itching in the mouth, skin redness, hives, nausea, or general discomfort after eating onions. Anyone who has experienced such reactions should avoid or strictly limit onion consumption.

People taking traditional herbal medicine or blood-thinning medications
Onions have a mild blood-thinning effect. For individuals taking anticoagulant drugs or certain traditional herbal medicines, consuming large amounts of onions may interfere with the effectiveness of these medications.

People preparing for surgery
Due to their potential effect on blood clotting, people who are about to undergo surgery are often advised to limit onion intake beforehand to reduce the risk of excessive bleeding.