Dry mouth may be caused by liver fire, stomach fire, or open-mouth breathing. There are several causes of dry mouth, but the common causes are stomach fire or liver fire. According to Chinese medicine, dry mouth is easily caused by liver fire or poor spleen and stomach. Chinese herbal medicine can be used to regulate it. Dry mouth may also be caused by drinking less water, or seasonal changes, indoor dryness, you can strengthen ventilation, or drink more water, eat more vegetables and fruits to improve. Dry mouth may also be a manifestation of inflammatory reaction. Inflammation of the oral mucosa, or acute tonsillitis, or acute pharyngitis can easily cause dry mouth. In this case, treatment of the original disease is needed. Dry mouth may also be related to the reduction of salivary gland secretion. Radiotherapy and chemotherapy after major surgery can easily cause a reduction of salivary gland secretion, or after sleepless nights, salivary secretion will also be reduced, and the oral mucosa lacks the buffer of saliva, resulting in dry symptoms. Dry mouth may also be related to open mouth breathing, the nose suffers from rhinitis or sinusitis and is forced to breathe through the mouth, making it easy to have dry mouth. Therefore, dry mouth is related to liver fire and stomach fire, and may also be related to acute pharyngitis or nasal disease.