Black tongue coating is caused by these reasons

Under normal circumstances, the color of the tongue coating is light pink. Once it turns black, it means that the problem is serious. It may be caused by gastrointestinal dysfunction, central nervous system dysfunction, infection and high fever, etc. In addition, this phenomenon may also occur in critically ill patients when their bodies are extremely weak.

1. Gastrointestinal dysfunction

Clinical observations show that more than half of the patients with black tongue coating have gastrointestinal symptoms such as abdominal distension, constipation, nausea, and poor appetite. Gastrointestinal dysfunction is one of the symptoms of poisoning. Gastrointestinal dysfunction is caused by the stimulation of bacterial toxins, which lowers the pH value of oral saliva, increases the adhesion between tongue cells, and lengthens the keratin protrusions of the filiform papillae, making them easily stained black by microorganisms, forming black tongue coating.

2. Central nervous system dysfunction

Mental stress can cause dysfunction of the central nervous system, which can increase the acidity in the mouth, favoring the growth of color-producing mold and resulting in black tongue coating.

3. Critically ill patients

Certain chronic diseases cause visceral failure, such as severe liver damage in the late stage of cirrhosis, chronic renal failure and uremia, and various late-stage cancers that lead to extremely weak physical constitution and black tongue coating.

4. Infection with high fever

Among 50 patients with black tongue coating, 36 had fever of varying degrees, including 20 with high fever and 16 with low fever. Most people develop black tongue coating during the process of fever. For some people, the black tongue coating disappears after the high fever subsides, but reappears when the fever occurs for the second time, proving that there is a certain relationship between fever and the appearance of black tongue coating. In addition, black tongue coating is also related to the length of time of fever. In the above cases, black tongue coating appeared after 4 days in the shortest fever and 80 days in the longest fever. In most cases, black tongue coating appears 2 weeks after fever, with an average of about 20 days. It can be seen that the longer the fever lasts, the more black tongue coating appears.