Why is the tongue coating black?

The colors of tongue coating vary. Some are green, some are white or yellowish. Very rarely, the tongue coating will turn black. If you suddenly find that your tongue has turned black, you should check whether you have eaten anything black recently, because the color of the food will also dye the tongue coating black. It may also be due to problems with the spleen and stomach, which will cause the tongue coating to become like this.

Etiology and pathogenesis/black tongue coating

Modern medical research shows that the formation of tongue coating is related to the overall nutritional status, local blood flow conditions, autonomic nervous function, saliva secretion and acute inflammatory stimulation, and it is believed that black tongue coating is mostly related to fungal infection. In addition, long-term and high-dose use of antibiotics can also easily cause black tongue. Traditional Chinese medicine believes that the tongue coating is derived from the stomach qi, and the twelve meridians also receive qi from the stomach. Therefore, the diseased qi of the internal organs can directly or indirectly connect with the tongue through the meridians to cause the appearance of black coating.

Gastrointestinal disorders

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.

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.

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.

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 during fever.