When people criticize someone for having a bad conscience, they often call them “black-hearted”. The medical condition of blackening of the internal organs does exist and is known as melanosis. In bed, this kind of black lesion mostly occurs in the digestive tract, especially in the large intestine, ileum, duodenum, esophagus and even the gallbladder. Due to the lack of knowledge about this disease, this kind of melanosis was rarely found in the past, and even less attention was paid to it. In recent years, with the popularization of electronic endoscopy, more and more colorectal melanosis has been detected; more relevant studies have concluded that colorectal melanosis is a precancerous lesion, which is associated with colorectal cancer. Therefore, colorectal melanosis has received a lot of attention from the medical community and patients. What is colorectal melanosis? It is a kind of non-inflammatory benign reversible disease characterized by pigmentation of the colonic mucosa. It is named because the mucosa of the colon appears brown or black under the endoscope. In modern society, people’s fast pace of life, high pressure, insufficient exercise, poor dietary habits such as nutrient imbalance, excessive protein and lipids in the diet, insufficient intake of dietary fiber, and stimulation of alcohol and tobacco have led to constipation has become a particularly common “fashionable disease”. Coupled with the pursuit of fashion, keen detoxification and weight loss; many people encounter constipation in life are accustomed to buy some bowel detoxification and laxative tea or drugs, taken in accordance with the instructions, few go to the hospital to consult a professional doctor to do the necessary checks. At the beginning, the effect of laxative may be good, and over time, often form drug dependence, the dose of drugs for bowel detoxification gradually increased, without the corresponding drugs it is more difficult to defecate. When you go to the hospital for examination, you will often find that the colon has become blackened and darkened. This phenomenon is not an isolated case in our hospital endoscopy and deserves attention. What are the causes? The pathogenesis of blackening of the colon is not well understood, but studies have confirmed that it is closely related to chronic constipation and long-term use of laxatives. These drugs are mainly Panax Leaf, Fruit Guide Tablets, Niuhuang Detoxification Tablets, Rhubarb Soda Tablets, Intestinal Clearance Tea, Detoxification Capsules, Aloe Vera, Cassia Seeds, etc. The main doctrines are: 1. retention theory, that is, due to chronic intestinal obstruction resulting in the retention of feces, proteolytic products under the action of enzymes into pigment particles deposited in the intestinal mucosa. 2. absorption theory, that is, due to the absorption of pigment particles synthesized by intestinal bacteria in the colon or the reduction of the ability of the colon to excrete pigment particles. 3. stimulation theory, that is, due to the stimulation of resinous substances contained in the laxative, the synthesis of pigment particles in the colon and then deposited in the intestinal lamina propria. The laxative causes damage to the intestinal epithelial cells, which are phagocytosed by the phagocytes in the lamina propria, and these large cell plasma pigment clusters make the intestinal mucosa appear black. 5. The laxative activates the activity of these enzymes, thus causing pigmentation, intestinal nerve disorders, etc. Chronic constipation caused by long-term intestinal dysfunction, long-term low-fiber diet, gradual weakening of the defecation reflex, prolonged accumulation of stool in the intestine, and absorption of pigment particles synthesized by bacteria in the intestine. In addition, the active or passive use of anthraquinone laxatives, which contain resinous substances, synthesize pigment granules in the colon, which are deposited in the lamina propria of the mucosa and engulfed by mononuclear cells to form melanosis. It is worth noting that there are many causes of constipation, the most common being constipation-type irritable bowel syndrome, and many other diseases such as colorectal tumors, inflammation, redundancy, prolapse, etc.; metabolic and endocrine diseases such as diabetes, hypothyroidism, etc.; neurological and muscular diseases such as sacral nerve injury, spinal cord tumors, congenital megacolon, etc. can cause constipation. Functional constipation, emphasis on dietary adjustments, more roughage, vegetables and fruits, less spicy and stimulating food, increase exercise, keep a happy mood, develop the habit of regular bowel movements, such as the need for medication should also be used under the guidance of a doctor. For organic constipation, the primary disease causing constipation should be treated, the surgery should be operated, not simply taking detoxifying drugs, so as not to delay the disease and endanger health.