The most common cause of colorectal nigrosis is a serpiginous change or pigmentation of the colon during colonoscopy. Colon melanosis is often due to prolonged constipation, and the process of constipation often take some laxatives, such as enteric tea or senna, can lead to pigmentation, resulting in stool color change, mostly dark red, brown or brown, is caused by pigmentation. In general, this situation, or first pay attention to improve the symptoms of constipation, you can give appropriate lactulose oral solution, bifidobacteria capsules and other symptomatic treatment, while discontinuing some related laxatives, because this type of laxative is a decisive factor in causing intestinal pigmentation. Therefore, improving gastrointestinal function and paying attention to physical exercise are the first choice to solve the problem of colorectal melanosis.