Onion is a vegetable containing pungent substances, which can be eaten raw or stir-fried. Its harm is mainly in the case of raw food, because it contains more stimulating pungent ingredients, can stimulate the oral mucosa, for patients with some oral diseases, easy to cause discomfort or make some symptoms worse. Onion contains protein, carbohydrates, a variety of vitamins and some amino acids and other ingredients, which can provide some of the nutrients for the body. But this vegetable also contains more methyl disulfide, allyl disulfide, trisulfide and other components, which is also the source of its pungent odor, if there are oral mucosal ulcers, it is easy to stimulate the ulcer surface and aggravate the pain. It is recommended that the onion can be fried and consumed, which can remove its pungent odor, can avoid some spicy ingredients to stimulate the oral mucosa patients and cause discomfort.