Bai Hu Tang (白虎汤): White Tiger Decoction — TCM's Classic Formula for High Fever

What Is Bai Hu Tang?

Bai Hu Tang (白虎汤), the “White Tiger Decoction,” is one of the most celebrated formulas in the TCM classics. Created by Zhang Zhongjing and recorded in the Shanghan Lun (Treatise on Cold Damage, circa 200 AD), it is the primary formula for clearing intense heat at the Qi level of the Four-Level (Wei-Qi-Ying-Xue) diagnostic system.

Why “White Tiger”?

In Chinese cosmology, the White Tiger (白虎) represents the West, the Metal element, autumn, and the Lung organ. The metaphor is deliberate — just as the tiger is fierce and powerful, this formula aggressively and decisively clears raging heat from the body. The association with the Lungs also reflects the formula’s action on the Lung and Stomach organs.

The Ingredients

Herb	Chinese	Dose	Role
Gypsum	Shi Gao (石膏)	30-60g (raw, crushed)	Chief — clears intense heat, generates fluids
Anemarrhena	Zhi Mu (知母)	9-15g	Deputy — clears heat, nourishes Yin, generates fluids
Licorice	Gan Cao (甘草)	6g	Assistant — protects Stomach, harmonizes the formula
Rice	Geng Mi (粳米)	15-30g	Assistant — protects Stomach, prevents Shi Gao from being too harsh

The elegance of this formula lies in its simplicity — only four ingredients, each with a clear purpose. Shi Gao is the “fire extinguisher,” Zhi Mu provides sustained heat-clearing while protecting Yin, and Gan Cao and Geng Mi form a protective base that shields the Stomach from the intense cold of the chief herbs.

The “Four Bigs” — Classic Indications

Bai Hu Tang is indicated by four hallmark signs known as the Si Da (四大):

1. Big Fever (大热)

• High fever, often 39°C (102°F) or above
• Fever that persists and feels intensely hot
• The patient feels hot to touch, especially the trunk

2. Big Thirst (大渴)

• Intense thirst with a desire for cold drinks
• Dry mouth and throat
• Consuming large quantities of water without relief

3. Big Pulse (大脉)

• A flooding, large, and forceful pulse (洪大脉)
• Feels like waves crashing — easy to feel, wide, and strong
• Indicates intense heat with strong pathogenic force but the body’s Zheng Qi is still robust

4. Big Sweat (大汗)

• Profuse sweating that does not relieve the fever
• Sweat is hot and profuse
• The body is trying to vent heat but the heat source is too strong

Additional Signs

• Tongue: Red body with a yellow, dry coating
• Face: Red, especially the cheeks
• Mental state: Restless, possibly mildly confused from heat
• Skin: Feels hot, may have a flushed appearance

Understanding Qi-Level Heat

In the Four-Level system (Wei → Qi → Ying → Xue), Bai Hu Tang addresses the Qi level, the second stage:

Level	Depth	Key Signs	Treatment Principle
Wei (Defensive)	Surface	Fever with chills, floating pulse	Release the exterior
Qi (Qi)	Interior — Organs	High fever, thirst, sweating, flooding pulse	Clear Qi-level heat
Ying (Nutritive)	Deeper	Fever worse at night, mental changes, dark red tongue	Clear Ying-level heat
Xue (Blood)	Deepest	Bleeding, loss of consciousness, purplish spots	Cool blood, open orifices

Qi-level heat means the pathogen has moved past the surface and is now generating intense heat inside the body, particularly in the Lungs and Stomach. The body’s Zheng Qi is still strong enough to fight (hence the forceful pulse), but the heat is fierce and needs immediate clearing.

Important Variations

Bai Hu Jia Ren Shen Tang (白虎加人参汤)

Adds Ren Shen (Ginseng, 9g) to the base formula:

• For Qi-level heat complicated by Qi and fluid deficiency
• When there is high fever with thirst but also fatigue, weakness, and dry mouth despite drinking
• The pulse is flooding but also feels slightly empty or deficient underneath
• Modern use: high fever with significant dehydration and exhaustion

Bai Hu Jia Gui Zhi Tang (白虎加桂枝汤)

Adds Gui Zhi (Cinnamon Twig, 9g) to the base formula:

• For Qi-level heat with concurrent joint pain (wind-damp-heat in the joints)
• When high fever is accompanied by joint heaviness and pain
• Historical use: malaria-like conditions with fever and joint pain

Bai Hu Jia Cang Zhu Tang (白虎加苍术汤)

Adds Cang Zhu (Atractylodes, 9g) to the base formula:

• For Qi-level heat with dampness
• High fever with a feeling of heaviness, nausea, and a greasy tongue coating
• Often used in summer when heat combines with dampness

Modern Clinical Applications

In contemporary practice, Bai Hu Tang is used for:

• High fever from influenza, pneumonia, or other infections
• Heatstroke with high body temperature and profuse sweating
• Diabetes with intense thirst (the “wasting-thirst” pattern, 消渴)
• Hyperthyroidism with heat signs, thirst, and restlessness
• Post-surgical fever with strong systemic heat response

Preparation and Dosage

Critical Decoction Instructions

1. Crush Shi Gao (Gypsum) — it must be broken into small pieces to release its properties
2. Cook Shi Gao first — add to water and bring to a boil, cook for 20-30 minutes before adding other herbs
3. Add Geng Mi (rice) and Zhi Mu after the initial Shi Gao cooking
4. Add Gan Cao last — simmer for another 10-15 minutes
5. Strain and take warm

Dosage Considerations

• Shi Gao dosage can range from 30g to 120g depending on severity
• For children, reduce all doses proportionally
• The formula should only be taken while heat signs are present — discontinue once fever breaks

Precautions and Contraindications

When NOT to Use Bai Hu Tang

• True cold patterns — the formula’s intense coldness would be devastating
• Heat at the Ying or Xue level — requires different formulas (Qing Ying Tang, Xi Jiao Di Huang Tang)
• Deficiency heat without excess — the harsh cold herbs will damage Yang Qi
• Weak patients with a deep, fine, forceless pulse — Zheng Qi is too weak for this aggressive formula
• Patients with chronic cold Spleen/Stomach — may cause diarrhea and worsen digestion

Safety Notes

• Bai Hu Tang is a powerful heat-clearing formula — it should be used under professional guidance
• Do not take for extended periods — once the fever breaks, the formula should be stopped
• Geng Mi (rice) and Gan Cao are essential to protect the Stomach from Shi Gao’s harshness

Key Takeaways

• Bai Hu Tang is the primary formula for intense Qi-level heat — the “Four Bigs” of high fever, intense thirst, flooding pulse, and profuse sweating
• Shi Gao (Gypsum) is the fierce chief herb that directly extinguishes raging heat
• Only four ingredients, but each is essential — including rice to protect the Stomach
• Named after the White Tiger to symbolize its aggressive, decisive heat-clearing power
• Stop using immediately once the fever resolves — its intense cold can damage Yang Qi if continued

Disclaimer: This article is for educational purposes only. Consult a licensed TCM practitioner for personalized formula prescriptions, especially for high fever.

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• Shanghan Lun: Treatise on Cold Damage
• Zhi Mu: Anemarrhena in TCM
• Huang Lian: Coptis in TCM
• Eight Principles of TCM Diagnosis