Dry diseases require lubrication. These diseases can be internal or external, and this class of herbs is used to treat both categories. Internal dryness may cause dry skin, constipation, discharge of dry and solid stools, scanty urine, thirst, dry throat with cracked lips, and sleeplessness, while external dryness may lead to the absence of perspiration in hot weather, blood in sputum, dry cough, dry nose, and dry skin.
This class of herbs is divided into three subclasses. The first subclass consists of herbs for lubricating the lungs, used to treat dryness and yin deficiency of the lungs, which can manifest in ailments such as loss of voice, coughing up blood, dry cough, atrophic rhinitis, common cold, influenza, bronchitis, diabetes insipidus, throat pain, dry nose and throat, and tickle in the throat. The second subclass consists of herbs for producing fluids and strengthening the stomach. These herbs produce fluids in the stomach, mainly for treating yin deficiency of the stomach, resulting in ailments such as diabetes mellitus, morbid hunger, dry lips, or stomachache. The third subclass consists of herbs for watering the yin (increasing yin energy in the body) and lubricating dryness of the intestines. These herbs are mostly used to treat yin exhaustion, dryness of the intestines, and dry constipation.
Herbs in this class can slow down movements inside the body, including energy circulation, blood circulation, and digestion. Therefore, individuals with poor energy circulation, poor blood circulation, or chronic indigestion should avoid this class of herbs.