There are many causes of smelly farts, mostly due to dietary factors, for example, eating too much gas-producing food or food that can easily stimulate intestinal bacteria to multiply, resulting in a large number of harmful bacteria to decompose the food and produce too much gas, resulting in a bad odor. It is possible that the diet is too greasy and indigestible, causing the food to stay in the gastrointestinal tract for too long and ferment abnormally, leading to the situation of smelly farts. In addition, it may also be related to constipation, in which the stool stays in the intestines for a long time and the bacteria multiply to produce too much foul-smelling gas. If farting odor occurs for a long time and is accompanied by abdominal pain, abnormal bowel habits or stool characteristics, consider the possibility of organic diseases of the intestinal tract, and need to be further examined by colonoscopy.