The left side of the stomach bloating and pain may be caused by physiological factors such as the intake of irritating foods, or it may be caused by pathological factors such as chronic gastritis and left hemicolonic obstruction. 1. Physiological factors: Consumption of spicy and stimulating, cold and greasy foods such as hot and spicy, garlic, ginger, onion, ice cream, coffee, alcohol, strong tea, etc., can stimulate the gastrointestinal mucosa, aggravate the burden on the gastrointestinal tract, and cause abdominal pain, abdominal distension, nausea, loss of appetite and other symptoms. 2. Pathologic factors: (1) Chronic gastritis: chronic inflammatory disease of the gastric mucosa can be caused by Helicobacter pylori infection, non-steroidal drugs such as aspirin, parasites, fungi, viruses, immunity and other factors, resulting in symptoms such as gastric distension, gastric pain, postprandial fullness and early satiety. (2) Left hemicolonitis: it can be caused by Mycobacterium tuberculosis infection, polyps, tumors, fungal infections and other factors, resulting in narrowing of the intestinal lumen, so that intestinal contents can’t pass through the intestinal lumen normally, and symptoms such as nausea, vomiting, stopping of defecation, abdominal distension, abdominal pain and so on appear. The left side of the stomach swelling and pain may also be ulcerative colitis and other diseases, it is recommended to consult a doctor to clarify the diagnosis, under the guidance of the doctor for targeted treatment.