The tongue can reflect changes in the five zang-organs and six fu-organs.
The tongue can be divided into four parts: the tip, the center, the root, and the sides. The pathological changes of the five zang-organs and six fu-organs can be reflected in these four parts.
Heart and Lungs → Tongue Tip
If a person has obvious red spots on the tongue tip, it may be due to excessive emotional changes, leading to heat in the heart and lungs, excessive heart fire, and poor sleep. In such cases, one should try to calm the mind and soothe the spirit to alleviate emotional fluctuations. A decoction of traditional Chinese medicines such as bamboo leaves and lotus seeds can be consumed, while also avoiding foods that are likely to cause internal heat.
Spleen and Stomach → Tongue Center
If a person's coating is only missing from the center of the tongue, while the rest of the tongue has a coating, they should pay close attention to their spleen and stomach and seek a gastroscopy at the hospital as soon as possible.
Kidneys, Bladder, and Urethra → Tongue Root
A thick, greasy white coating on the tongue root mostly indicates damp-heat in the lower jiao (the area below the navel in the abdominal cavity), manifesting as frequent urination, urgent urination, painful urination, or red urine, weight loss, cold hands and feet, a cold back, and loose stools. One should seek medical attention at the hospital promptly.
Liver and Gallbladder → Tongue Sides
If the color of the tongue sides is dark, it may indicate abnormal liver and gallbladder function.
In addition, ① An enlarged tongue reflects a problem with the spleen, which may be a deficiency of the spleen qi. If accompanied by symptoms such as general fatigue, loss of appetite, sweating easily, and soft stools, it indicates a weakened body resistance. ② A smooth tongue surface without a coating, known in Traditional Chinese Medicine as a "smooth tongue" or "mirror tongue," is caused by internal yin deficiency and heat, and yin fluid depletion, leading to symptoms like aversion to heat, irritability, dry mouth and throat, and dry stools. Eating sour foods such as black plum and hawthorn can help alleviate these symptoms. ③ A thin, white tongue coating indicates an external invasion of wind-cold. One should eat less raw, cold, spicy, and greasy food, pay attention to preventing cold and keeping warm, and ensure adequate sleep.