The dark red color of the tongue may be caused by yin deficiency, blood stasis, qi stagnation and other reasons. 1. Yin deficiency: mostly associated with sexual indiscretion, loss of yin fluid due to prolonged illness, and unclean eating habits, etc. Chinese medicine believes that yin deficiency is heat, which is manifested in clinical manifestations such as five-heart-heat (heat in the hearts of the hands and feet, and self-consciousness of the heart and chest), emaciation, zygomatic redness (reddish color in the cheeks and cheekbones), and a red tongue with little moss, etc. Therefore, patients with yin deficiency may have a dark red tongue. Therefore, patients with Yin deficiency may have a dark red tongue. 2. Blood stasis: The cause of this is related to trauma, cold invasion of the body, poor circulation of Qi, etc. The blood circulation of the body is out of order, which can lead to the phenomenon of dark red tongue. This kind of condition is often accompanied by stagnation of the veins and channels under the tongue. 3. Qi stagnation: generally associated with emotional depression, food accumulation (indigestion of food and its accumulation in the stomach) and other factors that lead to the poor functioning of the body’s qi, stagnation and blockage of the body’s qi stagnation in the body’s meridians and blood, etc., due to the different parts of the qi stagnation, which manifests the symptoms of tightness in the chest, coughing and a dark red tongue. If you find a dark red tongue, it is recommended that the patient go to a regular hospital to find out the cause of the disease and be treated under the guidance of a professional doctor’s diagnosis.