Toothache, gum swelling, gum bleeding, and oral malodour that does not respond to improved oral hygiene typically indicate a systemic rather than local cause. In TCM, the Stomach channel runs directly through the gums and the lower dental arch; when Stomach Fire accumulates and ascends through this channel, it produces the characteristic presentation that Li Dongyuan’s Qing Wei San (Clear the Stomach Powder) from Pi Wei Lun was designed to address: gum redness, swelling, and pain; or gum ulceration; oral malodour (heat-type); toothache worsened by hot food and heat exposure; dry mouth; and the complete Stomach-Fire constitutional picture of irritability, constipation, and dark urine. The formula’s five-herb design — Huang Lian as the primary bitter-cold Stomach-Fire extinguisher, Sheng Ma as the ascending-dispersing guide and Fire-venting agent, with Sheng Di Huang, Mu Dan Pi, and Dang Gui providing Blood-cooling, Blood-activating, and thermal-moderating actions — is a classic example of TCM’s “purge-and-cool combined, ascending and descending balanced” (xie qing bing shi, sheng jiang xiang yin) compositional logic.

I. Historical Source and Formula Rationale

Qing Wei San is recorded in Li Dongyuan’s Pi Wei Lun and subsequently in Yi Zong Jin Jian, Jing Yue Quan Shu, and other classics. The Yi Zong Jin Jian version adds Shi Gao to intensify the Stomach-Fire clearing for more severe presentations (gum ulceration, high-grade inflammatory response). Li Dongyuan recognised the specific failure of pure bitter-cold treatment: “If you use purely bitter-cold herbs to suppress Stomach Fire, two problems arise: (1) the bitter-cold congeals the channels, preventing Fire from escaping, causing the Fire to deepen rather than resolve; (2) prolonged bitter-cold treatment damages Spleen-Stomach Yang Qi, a particularly serious concern given the formula’s Stomach-channel target.” His solution: combine bitter-cold direct Fire-suppression (Huang Lian) with ascending-dispersing Fire-venting (Sheng Ma), cooling Blood (Sheng Di, Mu Dan Pi) with warming Blood-nourishment (Dang Gui). The Sheng Ma-Huang Lian pairing is the formula’s defining structural feature.

II. Five-Herb Composition and Formula Analysis

Classic composition: Huang Lian · Sheng Ma · Dang Gui · Sheng Di Huang (or Sheng Di) · Mu Dan Pi. Modern clinical reference doses: Huang Lian 6–9g · Sheng Ma 9g · Sheng Di 15g · Mu Dan Pi 9g · Dang Gui 9g. Yi Zong Jin Jian version adds: Shi Gao 20–30g (pre-decoct). Water decoction; 2 warm daily doses after meals.

Chief herb — Huang Lian 6–9g: extremely bitter, cold; enters Heart, Liver, Stomach, Large Intestine. Clears Heat and dries Damp, purges Fire and detoxifies. The formula’s primary weapon against Stomach-Fire: Huang Lian’s extreme bitter-cold nature directly suppresses accumulated Stomach Fire at its source. The Stomach channel’s tendency to produce “multi-Qi and multi-Blood” (duo qi duo xue) patterns means Stomach Fire, once established, burns intensely and requires a genuinely powerful cold-purging agent. However, unmodified Huang Lian risks “bitter-cold destroying the Stomach” (苦寒败胃) — hence the four companion herbs. Huang Lian’s dose (6–9g) is controlled: sufficient to extinguish the Fire, insufficient to damage the Stomach.

Deputy herb — Sheng Ma 9g: pungent-sweet, slightly cold; enters Lung, Spleen, Stomach, Large Intestine. Clears Heat and detoxifies, raises Yang and disperses, vents rashes. Sheng Ma’s role is architecturally critical and embodies the formula’s core innovation:

• Disperses suppressed Fire outward (火郁发之): the Nei Jing principle that “Fire constrained must be vented” — pure bitter-cold suppression drives Fire inward rather than resolving it; Sheng Ma’s ascending-dispersing quality opens the exit pathway, allowing accumulated Stomach-Fire to vent upward and outward rather than deepening
• Guides herbs to the Yangming Stomach channel and its upper facial region: Sheng Ma is the Yangming channel’s guide herb; it carries Huang Lian, Sheng Di, and Mu Dan Pi directly to the Stomach channel’s gum-tooth-oral distribution territory
• Clears residual Heat-toxin from inflamed gum tissue independently

The Huang Lian-Sheng Ma pairing is the formula’s defining dyad: one descends-suppresses (Huang Lian), one ascends-vents (Sheng Ma) — “one descending, one ascending; one purging, one dispersing” ensures Fire is both suppressed and expelled, not merely driven deeper.

Assistant herbs — Sheng Di Huang, Mu Dan Pi, and Dang Gui:

• Sheng Di Huang 15g: sweet-bitter, cold; enters Heart, Liver, Kidney. Clears Heat and cools Blood, nourishes Yin and generates fluids. The Stomach is a “multi-Blood” organ; prolonged Stomach-Fire scorches the Blood vessels of the gum (Stomach channel’s tissue distribution), producing gum bleeding, ulceration, and Blood-Heat-driven redness and pain. Sheng Di cools this Blood-Heat, stops gum haemorrhage, and simultaneously nourishes the Yin-fluids depleted by the Stomach Fire (addressing the oral dryness and constipation component).
• Mu Dan Pi 9g: bitter-pungent, slightly cold; enters Heart, Liver, Kidney. Clears Heat and cools Blood, activates Blood and disperses Stasis. Amplifies Sheng Di’s Blood-cooling action; additionally resolves the Blood-Stasis component — sustained Stomach-Fire obstruction creates Blood-Stasis in the gum vasculature, producing the hard, non-pitting swelling and fixed pain of stasis-pattern gum disease. Mu Dan Pi’s Blood-activating quality resolves this Stasis “without leaving residue” (cool without clogging). Also moderates Sheng Ma’s pungent-warm tendency.
• Dang Gui 9g: sweet-pungent, warm; enters Liver, Heart, Spleen. Supplements Blood and activates Blood, relieves pain, moderates the formula’s cold-heavy composition. Dang Gui serves a critical thermal-moderating function: its warm nature prevents Huang Lian, Sheng Di, and Mu Dan Pi’s cold nature from clogging Stomach circulation or damaging Spleen-Yang. It nourishes Blood-vessels scorched by Fire, facilitating healing of gum tissue. Its Blood-activating quality supports Mu Dan Pi in resolving vascular Stasis. Without Dang Gui, the formula would be excessively cold-biased; with Dang Gui, it achieves “cool without congealing.”

Optional addition: Shi Gao 20–30g (Yi Zong Jin Jian version; pre-decoct): pungent-sweet, very cold; enters Lung, Stomach. When Stomach Fire is extremely severe (gum ulceration, very high fever, intense pain), Shi Gao’s extraordinary cold force is needed to break the Fire directly. Not included in Li Dongyuan’s original for moderate presentations.

Three-layer formula logic:
① Clear Stomach Fire (Huang Lian + Sheng Ma + optional Shi Gao): direct Fire suppression + Fire venting — the purge-and-vent combined strategy
② Cool Blood and nourish Yin (Sheng Di + Mu Dan Pi): address Blood-Heat and Blood-Stasis in the gum vasculature; nourish depleted Yin-fluids
③ Warm-moderate and guide (Dang Gui + Sheng Ma): prevent cold excess from congealing; guide herbs to Yangming channel; promote Blood-vessel healing

III. Formula Differentials

IV. Clinical Applications and Modifications

Core pattern: Stomach-Fire excess with Blood-Heat
Gum redness, swelling, and pain (heat-type — worse with hot foods and heat application, better with cold); toothache; gum bleeding on brushing; oral malodour (heat-odour, not odour from food retention); mouth sores and ulcers; dry mouth; constipation; dark urine; irritability; red tongue with yellow coating; slippery-rapid or forceful-rapid pulse. Triggered or worsened by: spicy-oily diet, alcohol, emotional stress.

1. Periodontitis and gingivitis (Stomach-Fire type): gum redness, bleeding, and pain with oral malodour and constipation; Stomach-Fire constitutional picture. The formula’s primary modern application. Modifications: pus from gum abscess → add Jin Yin Hua 12g, Pu Gong Ying 15g; swelling severe → add Huang Bai 9g, Zhi Zi 9g.

2. Oral ulcers — Stomach-Fire type: red, painful oral and tongue ulcers; oral malodour; constipation; red tongue with yellow coating; rapid pulse. Huang Lian as the specific Stomach-Fire clearing agent is highly effective for this pattern. Modifications: ulcers severe → add Huang Bai 9g, Huang Lian increase; concurrent Heart-Fire (tip-of-tongue red, restlessness) → add Zhu Ye 9g, Deng Xin Cao 3g.

3. Dental abscess and periapical periodontitis (Stomach-Fire type): acute toothache with gum abscess formation; red swollen cheek; fever in acute stage; Stomach-Fire pattern. Note: dental abscess requires dental treatment; Qing Wei San is an adjunct to — not a replacement for — appropriate dental care. Modifications: add Da Huang 6g (add last) for severe constipation and fever; add Lian Qiao 9g for Heat-toxin.

4. Facial erythema and skin conditions driven by Stomach-Fire: flushed cheeks; facial acne with Stomach-Fire constitutional picture (oral malodour, constipation, greasy diet). Often combined with Pi Pa Qing Fei Yin.

5. Gastric diseases with prominent Stomach-Fire: gastric burning pain; acid reflux with heat sensation; Stomach Fire pattern without significant Yin-deficiency. Modifications: add Hai Piao Xiao 15g (antacid), Bai Ji 9g (mucosal repair).

Common modifications:

• Heat-toxin and abscess: add Jin Yin Hua 12g, Pu Gong Ying 15g, Zi Hua Di Ding 12g
• Gum bleeding prominent: increase Sheng Di to 20g; add Ce Bai Ye 12g, Bai Mao Gen 15g
• Constipation severe: add Da Huang 6–9g (add last), Mang Xiao 6g (dissolve into strained liquid)
• Stomach Fire very severe (Yi Zong Jin Jian version): add Shi Gao 20–30g (pre-decoct)
• Yin deficiency co-pattern (floating toothache, loose teeth, hot palms): switch to Yu Nu Jian or add Zhi Mu 10g, Mai Dong 12g
• Spleen-Stomach weakness risk (weak constitution, history of loose stool): reduce Huang Lian to 4–6g; add Bai Zhu 12g, Fu Ling 15g

V. Usage, Dosage, and Safety

Preparation: water decoction; Shi Gao pre-decoct 30 min (if used); 2 warm doses daily after meals. Patent forms: Hai Tian Qing Wei San and Nong Ben Fang Qing Wei San.

Contraindications: Spleen-Stomach Cold deficiency (cold aversion, loose stool, cold abdomen, pale tongue, white coating) — Huang Lian and Sheng Di will seriously worsen Cold; Yin-deficiency toothache (floating dull tooth pain, worse at night, loose teeth, hot palms, red tongue with scant coating — this is Yu Nu Jian’s pattern, not Qing Wei San’s); Wind-Cold or Wind-Heat toothache without Stomach-Fire constitutional picture; pregnant women (Mu Dan Pi and Dang Gui have Blood-activating properties; use under supervision); allergy to any component.

Course: acute Stomach-Fire conditions (gum abscess, acute gingivitis) typically respond within 3–5 days; do not continue beyond symptom resolution. For recurrent gum disease and oral ulcers, concurrent dental treatment, dietary modification, and emotional regulation are essential to prevent relapse — the formula addresses the acute Fire but the lifestyle driving the Fire generation must also be addressed.

Lifestyle co-treatment: reduce or eliminate spicy, oily, deep-fried, and alcohol-containing foods; reduce sugar; establish regular meal times; manage stress and emotional agitation (Liver-Qi transforming to Fire then attacks Stomach); maintain good oral hygiene (formula reduces systemic Fire but does not replace local dental hygiene); drink adequate water.