中央黄色。入通于脾。开窍于口。胃脉挟口环唇。大肠脉还出挟口。厥阴脉
下颊里环唇内。又皆统之于脾矣。独其邪之所侵。火热则赤。木乘则青。气
虚则白。火极似水则焦黑。水极似火则裂坼。一寒一热。判若天渊。胃热脉
洪。责于心火。内炽脾虚。脉弱本于阴寒上逼。清胃凉膈。所以彻热。附子理
中。所以温里。今人一见唇焦。便指为热。不知中气虚寒。饮食不进。中焦失
守。无根之火。逼而上浮。若以寒凉投之。则火愈不归。而食愈不进。惟人参
理中。温其中气。火奠厥位。而唇口坼裂。如久旱逢霖。立时润泽矣。至乃舌
为心苗。脾之络。连舌本。散舌下。肾之脉。亦系舌本。伤寒家验舌苔。以焦黑
为胃热。为水枯。则本此。若别口味之辛甘咸苦酸。以察五脏之热。尤其显
白者。则各以其脏治之。斯善耳。要之二阳之病发心脾。火土子母相关。岂浅鲜哉。
一口病实热。脉洪数有力者。用清胃汤。
一口病饮食不进。脉微细软弱者。用人参理中汤。或归脾汤加炮姜。
一谋虑不决。上为口糜。用逍遥散。或升阳散火汤。大肠移热。用秦艽升麻汤。
清胃伤 治胃火血燥唇裂。或为茧唇。或牙龈溃烂作痛。
黄连（炒） 生地黄 升麻（各一钱） 当归（一钱二分） 牡丹皮（八分）
水煎。
The center corresponds to the color yellow, and its qi communicates with the Spleen (Pi, 脾). The orifice of the mouth opens externally, closely related to the Stomach and Spleen. The meridian of Foot-Yangming Stomach (Zu Yangming Wei Jing, 足阳明胃经) runs alongside the lips and encircles them; the meridian of Hand-Yangming Large Intestine (Shou Yangming Da Chang Jing, 手阳明大肠经) returns and also runs alongside the lips; the meridian of Foot-Jueyin Liver (Zu Jueyin Gan Jing, 足厥阴肝经) descends into the cheek interior and encircles the inner lips. The qi and blood flow of these meridians are all governed by the Spleen.
However, manifestations of pathogenic invasion on the lips vary: invasion by Fire-Heat (Re, 热) causes redness; Wood (Liver) overacting causes blueness; Qi deficiency causes pallor; extreme Fire resembling Water (True Cold, False Heat) causes charring/blackening; extreme Water resembling Fire (True Heat, False Cold) causes cracking/fissuring. One is cold, one is heat, differing as vastly as heaven and earth.
If the pulse is surging (Hong, 洪) due to Stomach Heat, the responsibility lies in the internal blazing of Heart Fire (Xin Huo, 心火); if the pulse is weak due to Spleen Deficiency, the root cause is the upward coercion of Yin-Cold (Yin Han, 阴寒). Using methods to clear the Stomach and cool the Diaphragm aims to thoroughly eliminate Heat; using Fuzi Lizhong Tang (Aconite Decoction for Regulating the Middle) aims to warm the Interior.
Modern practitioners, upon seeing charred lips, immediately diagnose it as Heat, unaware that this may be Deficient-Cold of the Middle Qi, leading to loss of appetite, failure of the Middle Jiao to maintain control, and Rootless Fire being coerced upward. If cold-natured drugs are administered at this time, the Fire will fail to return to its proper position, and food intake will further decrease. Only by using Renshen Lizhong Tang (Ginseng Decoction for Regulating the Middle) to warm the Middle Qi can the Fire be settled in its proper place. Consequently, the cracking and fissuring of the lips and mouth will be instantly moistened and healed, like rain falling after a long drought.
Regarding the tongue, it is the sprout of the Heart, the collaterals of the Spleen connect to the root of the tongue and scatter beneath it, and the meridian of the Kidney also ties to the root of the tongue. Practitioners of Shanghan (Cold Damage) examine the tongue coating, considering blackening to indicate Stomach Heat or exhaustion of Body Fluids (Jin Ye, 津液), based on these theories. Furthermore, by distinguishing tastes such as pungent, sweet, salty, bitter, and sour to observe Heat in the Five Zang Organs, and treating each organ accordingly when signs are prominent, one demonstrates superior skill. In summary, "Diseases of the Two Yangs originate from the Heart and Spleen"; the mother-child relationship between Fire and Earth (Heart and Spleen/Stomach) is significant, and its principles are not trivial.
1. For mouth diseases characterized by Excess-Heat, with a surging, rapid, and forceful pulse, use Qingwei Tang (Clear the Stomach Decoction).
2. For mouth diseases presenting with loss of appetite and a faint, thin, soft, and weak pulse, use Renshen Lizhong Tang (Ginseng Decoction for Regulating the Middle). Alternatively, use Guipi Tang (Restore the Spleen Decoction) with roasted Sheng Jiang (Prepared Ginger).
3. For indecisive planning leading to oral ulcers (Kou Mi, 口糜) ascending from above, use Xiaoyao San (Free and Easy Wanderer Powder). Or use Shengyang Sanhuo Tang (Raise Yang and Disperse Fire Decoction). If caused by Heat transferring from the Large Intestine, use Qinjiao Shengma Tang (Gentian and Cimicifuga Decoction).
[Formula] Qingwei Shang (Clear Stomach Injury - *Note: Text likely refers to a variation of Qingwei San*)
Indications: Lip fissures due to Stomach Fire and Blood Dryness. Or formation of callosous lips (Jian Chun, 茧唇), or ulceration and pain of the gums.
Ingredients: Huang Lian (Stir-fried Coptidis Rhizoma), Sheng Di Huang (Rehmanniae Radix Preparata), Sheng Ma (Cimicifugae Rhizoma) (each 1 qian), Dang Gui (Angelicae Sinensis Radix) (1.2 qian), Mu Dan Pi (Moutan Cortex) (0.8 qian).
Administration: Decoct in water and drink.