What causes pain on the left side of the stomach after eating?

Left-sided upper abdominal pain after eating may be caused by indigestion or conditions such as colitis or intestinal obstruction.

1. Indigestion

Eating too quickly, overeating, or consuming foods that are excessively hard, raw, cold, or greasy may lead to indigestion, resulting in various gastrointestinal symptoms—including left-sided upper abdominal pain after meals, belching, nausea, and vomiting.

2. Colitis

Long-term consumption of overly refined diets with insufficient intake of vegetables and fruits, or infection by bacterial or viral pathogens, may trigger colitis—characterized by inflammatory changes in the colon—and cause symptoms such as left-sided upper abdominal pain after meals, diarrhea, purulent or bloody stools, and constipation.

3. Intestinal Obstruction

Consumption of spicy, high-salt, or fatty foods—or underlying conditions such as intussusception or excessive length of the sigmoid colon—may lead to narrowing or blockage of the intestinal lumen, resulting in intestinal obstruction. This impairs normal intestinal motility or causes abnormal intestinal contractions, preventing the smooth passage of intestinal contents and producing symptoms including left-sided upper abdominal pain after meals, nausea, vomiting, and abdominal distension.