Constipation can cause bad breath, but bad breath is not necessarily the only symptom of constipation. Constipation usually causes bad breath due to poor stool excretion, and some of the gaseous components are vomited out through the upper digestive tract, resulting in the appearance of bad breath. Bad breath can also be caused by oral disorders such as periodontal disease, dental caries, etc. It may also be caused by upper respiratory tract or throat problems, and in recent years, gastritis, gastric ulcer and other diseases such as the detection rate of Helicobacter pylori is relatively high, the bacteria can also induce bad breath. Generally after killing the bacteria can get relief or improve bad breath, so not only constipation can cause bad breath, other diseases can also cause bad breath such as oral cavity, throat or with the digestive tract and other organ system disorders also have a certain relationship, need to be integrated and analyzed.