There is a relationship between the occurrence of mouth ulcers and eating. Summarizing the personal experiences provided by patients with recurrent mouth ulcers, there are some foods listed below that may be associated with the recurrence of mouth ulcers. People refer to these foods that may cause the disease as “hairy foods”. Various kinds of pickled products: such as pickled vegetables, salted meat, salted fish, etc. Especially “old pickled vegetables”, “old salted meat”, etc. that have been pickled repeatedly or for too long. A variety of bamboo shoots and bamboo shoots products: asparagus, bamboo shoots, bamboo shoots, dried bamboo shoots, etc. Various smoked and fried foods: smoked fish, chicken, meat and fried chicken legs, fried ribs, etc. A variety of preserved products: bacon, ham, etc. A variety of fried fruit: fried peanuts, fried melon seeds, etc. As well as with a very strong stimulating chili pepper, pepper, vinegar, soju, ginger, garlic, pepper, coffee, mustard, onion, etc. Of course, “hair” often varies from person to person. What is threatening to one person may not be harmful to another. Therefore, patients should not “avoid eating on a large scale” after reading this article. Instead, they should “abstain from eating” according to their actual situation, otherwise they are prone to nutritional imbalance, which is not good for mouth ulcer recovery.