口甜，是肝热脾湿，胃有痰滞。
口淡，是胃热。
口干口燥，是胃家热极。
口咸，是肾水上泛，肾热。
口酸，是肝热。
口干，是脾热。
口辛，是肺热。
口臭，是胃热。
口苦，是心热或胆热。更有因谋虑不决，肝移热于胆，而口苦者。（盖肝主谋虑，胆
主决断，倘事或胆不决则恚怒，胆汁上溢而口苦。
口酸，有脾胃气弱，木乘土位而酸者。
口糜，有膀胱移热于小肠，而口糜溃烂者。
《折衷》云∶脾脏应肾，通口气，脾胃为合，足阳明胃之经，其脉挟口环唇，故
脾胃受邪，则唇为之病。风则动，寒则紧，燥则干，热则裂，气郁则生疮，血少则涩
而无血色。然六腑之华，亦在唇。经云∶脾胃、大肠、小肠、三焦、膀胱者，仓廪之
本，营之居也，其华在唇。且肝脉、督脉、冲脉、任脉皆络于唇，一有受邪，则唇为病。
又曰∶喘而唇缩者，死。
又曰∶小儿唇红如丹，即发渴候，红甚焦黑则危。
冯鲁瞻曰∶唇本脾之外候，然足阳明脉亦起鼻而环于唇，故凡停滞伤脾，必气
粗唇坚而发肿，名曰唇肿。至有伤寒，或发惊候，是以眉棱骨痛，厥热眩闷，气秽
颐浮，或舌苔，或齿击，或狂逆，则又色白肿甚，名曰茧唇。若至胃伤极而唇烂，壮
热秽甚见痘者，名曰胃烂唇枭，十救一二。如忧愁劳极，满唇破裂者，亦名曰口糜。如
风寒乍乘，唇青带白者，宜温胃驱风。如吐后而唇白者，治宜养胃调气。如怒气上
冲，唇青者，治宜顺气平肝和胃。更有唇
口蠕动者，脾虚不能收摄也。
Sweet taste in the mouth indicates Liver Heat (Gan Re, liver heat) and Spleen Dampness (Pi Shi, spleen dampness), with Phlegm Stagnation (Tan Zhi, phlegm stagnation) in the Stomach.
Bland taste in the mouth indicates Stomach Heat (Wei Re, stomach heat).
Dryness and thirst in the mouth indicate Extreme Heat (Re Ji, extreme heat) in the Stomach House (Wei Jia, stomach region).
Salty taste in the mouth indicates Rising of Kidney Water (Shen Shui Shang Fan, kidney water flooding upward) and Kidney Heat (Shen Re, kidney heat).
Sour taste in the mouth indicates Liver Heat (Gan Re, liver heat).
Dry mouth indicates Spleen Heat (Pi Re, spleen heat).
Pungent/spicy taste in the mouth indicates Lung Heat (Fei Re, lung heat).
Foul breath indicates Stomach Heat (Wei Re, stomach heat).
Bitter taste in the mouth indicates Heart Heat (Xin Re, heart heat) or Gallbladder Heat (Dan Re, gallbladder heat). Furthermore, there are cases where indecisive deliberation causes the Liver to transfer Heat to the Gallbladder, resulting in a bitter taste. (The Liver governs deliberation, and the Gallbladder governs decision-making; if one is indecisive regarding matters, anger arises, causing Gallbladder Juice to overflow upward and leading to a bitter taste.)
Sour taste in the mouth can also result from Weakness of Spleen and Stomach Qi (Pi Wei Qi Ruo, deficiency of spleen and stomach qi), where Wood overacts on Earth (Mu Cheng Tu Wei, liver wood invading spleen earth).
Mouth ulcers (Kou Mi, oral mucosal erosion/ulceration) can occur when Heat from the Bladder transfers to the Small Intestine, causing erosion and ulceration in the mouth.
*Zhezhong* states: The Spleen corresponds to the Kidney, connecting through the mouth's breath; the Spleen and Stomach form an interior-exterior pair. The Foot-Yangming Stomach Meridian (Zu Yangming Wei Jing, meridian of foot yangming stomach) runs alongside the mouth and encircles the lips. Therefore, when the Spleen and Stomach are invaded by pathogenic factors, diseases manifest in the lips. Wind causes movement, Cold causes tightness, Dryness causes dryness, Heat causes cracking, Qi Stagnation (Qi Yu, qi depression/stagnation) causes sores, and Blood Deficiency (Xue Shao, blood deficiency) causes roughness and lack of color. However, the brilliance of the Six Fu Organs (Liu Fu, six fu organs) also manifests in the lips. The Classics state: The Spleen, Stomach, Large Intestine, Small Intestine, Sanjiao (Triple Burner), and Bladder are the roots of the granary and the residence of Ying Qi (Nutritive Qi); their brilliance manifests in the lips. Moreover, the Liver Meridian, Du Meridian (Governor Vessel), Chong Meridian (Penetrating Vessel), and Ren Meridian (Conception Vessel) all connect to the lips. Once any of these are invaded by pathogens, diseases manifest in the lips. It is further stated that panting accompanied by retraction of the lips indicates death.
It is also stated that if an infant's lips are red like cinnabar, it is a precursor to thirst; if the redness becomes scorched black, the condition is critical.
Feng Luzhan said: The lips are essentially the external manifestation of the Spleen. However, the Foot-Yangming Meridian also originates at the nose and encircles the lips. Therefore, whenever food stagnation injures the Spleen, there will inevitably be coarse breathing, hard and swollen lips, named Lip Swelling (Chun Zhong, lip swelling). In cases of Cold Damage (Shang Han, cold damage disease) or convulsive disorders, accompanied by pain in the supraorbital ridge, alternating cold and fever, dizziness and oppression, foul breath, facial puffiness, abnormal tongue coating, teeth grinding, or maniacal behavior, the lips may become white and severely swollen, named Silkworm Cocoon Lip (Jian Chun, silkworm cocoon lip). If the Stomach is extremely injured and the lips rot, accompanied by high fever, severe foulness, and appearance of pustules, it is named Rotting Stomach Lip Owl (Wei Lan Chun Xiao, rotting stomach lip owl), with only one or two out of ten recoverable. If due to excessive worry and fatigue, the entire mouth and lips crack, it is also named Mouth Ulcers (Kou Mi, oral erosion). If Wind-Cold suddenly invades and the lips are blue with white patches, treatment should warm the Stomach and expel Wind. If the lips are white after vomiting, treatment should nourish the Stomach and regulate Qi. If anger rushes upward and the lips turn blue, treatment should soothe Qi, calm the Liver, and harmonize the Stomach. Furthermore, twitching or quivering of the lips and mouth indicates Spleen Deficiency (Pi Xu, spleen deficiency) failing to maintain control.