The common causes of stomach pain when eating chili peppers are allergy, irritable bowel syndrome and gastric ulcers. 1. Allergy: If the gastrointestinal tract is allergic to the ingredients in chili peppers, the immune response releases histamine and other immune factors that can stimulate the gastrointestinal mucosa to produce pain. 2. Irritable bowel syndrome: irritable bowel syndrome can lead to increased sensitivity of internal organs, especially the rectum, after eating chili peppers capsaicin stimulation of the rectal mucosa, will cause pain, usually accompanied by diarrhea or constipation and other symptoms. 3. Gastric ulcer: after eating chili peppers, capsaicin contained in chili peppers will stimulate the ulcer surface on the gastric mucosa, which can cause burning pain. In addition, chili peppers cause the gastric mucosa to secrete more gastric acid, gastric acid stimulation of the gastric mucosa on the ulcer surface will also cause pain. If you eat chili stomach ache, you should go to the hospital to find out the cause of the disease, do not delay.