Flatulence on the left side of the stomach is associated with intestinal tuberculosis, constipation, ulcerative colitis, indigestion and other factors. The onset of intestinal tuberculosis is related to Mycobacterium tuberculosis infection, which not only causes lumps to appear in the intestinal area, but also affects the function of the intestinal tract, causing the intestinal wall to be unable to absorb the gas in the intestinal cavity, and therefore will be accompanied by a feeling of bloating, especially on the left side of the stomach. Constipation is accompanied by difficulty in defecation and prolonged bowel movement. Since the sigmoid colon and rectum are located in the lower left side of the abdomen, the main manifestation is flatulence on the left side of the stomach. Some people have ulcerative colitis, a disease that affects the function of the colon. Not only is the colon unable to help shape the stool, but the absorption of gas and water is also affected, so the patient may experience bloating, some of which is predominantly on the left side of the stomach. In case of indigestion, some undigested food will cause irritation to the intestinal wall when it enters the intestinal tract, so many people with indigestion will have a bloated stomach.