Consider that an upset stomach after eating instant noodles may be caused by gastrointestinal disorders, dietary factors, and other factors. For women of childbearing age, the possibility of pregnancy should also be ruled out. 1. Gastrointestinal diseases: Gastritis, gastric ulcer and other diseases, due to the difficulty of digestion, eating instant noodles may stimulate the secretion of gastric acid, aggravate the condition, and the upset stomach occurs. 2. Food factors: some people are allergic to the seasoning or pastry in the instant noodles, and may also experience stomach discomfort after eating, which may also be accompanied by rashes. If you eat expired instant noodles, food poisoning may also occur, resulting in acute gastroenteritis. 3. Pregnancy: For women of childbearing age, it is important to consider whether the symptoms of stomach discomfort are caused by early pregnancy. If the above symptoms occur, you need to go to the hospital in time, and under the guidance of a professional physician to clarify the cause of the disease, and then carry out targeted treatment.