Black tongue coating in the middle is mostly considered to be caused by Qi stagnation and blood stasis, dampness and heat in the spleen and stomach, and weakness of the spleen and stomach. There are many specific reasons for this, so it is recommended to consult a doctor. 1. Qi stagnation and blood stasis: black tongue coating caused by Qi stagnation and blood stasis is often accompanied by dull pain, distension, stabbing pain or cramping pain in the heart, chest, ribs, stomach and abdomen (gastric and abdominal areas); the pain is erratic, or fixed and persistent. 2. Dampness-heat in the spleen and stomach: tongue coating black in the middle caused by dampness-heat in the spleen and stomach, often accompanied by epigastric and abdominal fullness (stomach distension and discomfort), inappetence, vomiting, aversion to greasy, body fatigue and heaviness, body heat, bitter taste in the mouth, thirst and not much to drink, and scanty and yellowish urine. 3. Weakness of the spleen and stomach: The black tongue coating caused by weakness of the spleen and stomach is often accompanied by diarrhea, yellowish color, fatigue (lack of spirit), tiredness, and thinness. If the symptoms of black tongue coating are not relieved for a long time or accompanied by other discomforts, consult a doctor in time to find out the cause and carry out targeted treatment.