Bai Zhi (Angelica dahurica, Dahurian Angelica root) is the dried root of a Umbelliferae plant, also known as Xiang Bai Zhi and Fang Xiang. Its functional character can be summarised in four Chinese characters: san (scatter exterior Wind-Cold), tong (open and unblock the nasal orifice and channels), zao (dry Damp and stop leucorrhoea), and xiao (disperse and drain carbuncle-swelling). Pungent, warm, and powerfully aromatic, it enters Stomach, Large Intestine, and Lung channels. The pungent quality disperses and penetrates; the warm quality scatters Cold; the aromatic quality opens and unblocks. Together these produce a herb that is simultaneously a surface-resolver, a pain reliever specialising in Yangming-channel headache, a nasal decongestant, a leucorrhoea-drying agent, and a carbuncle-reducing herb. The Shen Nong Ben Cao Jing records it as an upper-class drug; the Ben Cao Gang Mu specifies its treatment of: nasal deep-source infection (bi yuan), epistaxis, tooth pain, supraorbital ridge pain, and the classical single-herb formula Du Liang Wan — Bai Zhi alone, powdered and formed into honey pills, taken with tea — for head-Wind dizziness and Wind-Cold headache.

I. Classical Records and TCM Properties

Four classical benchmarks:

• Shen Nong Ben Cao Jing (upper-class): “governs female leucorrhoea, blood obstruction and genital swelling, alternating Cold-Heat, Wind-head invasion with tearing eyes; promotes muscle growth and skin lustre; can be made into face cream” — both medicinal and cosmetic value established
• Ming Yi Bie Lu: extends to Wind-evil therapy, chronic thirst with vomiting, rib-flank fullness, Wind-pain, head dizziness and eye itching; use as medicated plaster
• Ben Cao Gang Mu: Li Shizhen specifies nasal deep-source infection, epistaxis, tooth pain, supraorbital ridge pain, and records Du Liang Wan (single-herb Bai Zhi formula for head-Wind dizziness)
• Yao Xing Lun: “eats through pus, stops heart-abdomen Blood piercing pain” — the drain-pus action established

TCM properties: Pungent, warm; enters Stomach, Large Intestine, and Lung channels. Pungent disperses and penetrates; warm scatters Cold; aromatic opens orifices and unblocks channels. No significant toxicity; relatively safe at standard doses; drug nature is balanced for a surface-resolving herb.

Regional varieties: Hang Bai Zhi (Zhejiang), Qi Bai Zhi (Hebei Anguo), Yu Bai Zhi (Henan), Chuan Bai Zhi (Sichuan). Zhejiang and Sichuan production is considered highest quality. Quality criteria: thick roots, heavy weight, good starchiness, strong aromatic fragrance.

Appearance: Long conical shape, 10–25cm × 1.5–2.5cm; surface grey-brown to yellow-brown with longitudinal wrinkles, subsidiary root scars, and lenticel-like transverse protrusions; hard and firm; cross-section white or grey-white, starchy, with scattered brown oil spots in the cortex; aromatic fragrance; pungent and mildly bitter taste.

Processing: Primarily used raw (most potent aromatic dispersal, best for resolving surface and relieving pain); light dry-roasting slightly moderates the pungent-warm intensity for longer-term use with less Spleen-Stomach irritation.

II. Five Core Actions

1. Resolve exterior and scatter Wind-Cold: Pungent-warm dispersal drives Wind-Cold off the surface. Addresses Wind-Cold common cold: aversion to cold, fever, absence of sweat, headache, nasal congestion with clear discharge, and generalised aching. Used in the Wind-Cold exterior stage alongside other surface-resolving herbs. However, Bai Zhi’s unique contribution among surface-resolvers is that it simultaneously addresses the Stomach and Large Intestine channels, making it particularly appropriate when the Wind-Cold presentation includes facial symptoms (nasal congestion, frontal headache, supraorbital pain) rather than the purely posterior-cranial or whole-body presentations of Qiang Huo or Fang Feng.

2. Dispel Wind and relieve pain — speciality: Yangming-channel pain: Bai Zhi’s most clinically important and distinctive action. It enters the Yangming (Stomach and Large Intestine) channel, which traverses the face, forehead, supraorbital region, and teeth. Bai Zhi is therefore the primary herb for:

• Frontal headache and supraorbital ridge pain (mei leng gu tong): the Yangming channel’s facial territory; Bai Zhi reaches this area specifically
• Toothache: both Wind-Cold type (pair with Xi Xin, Chuan Xiong) and Wind-Heat type (pair with Shi Gao, Jing Jie Sui)
• Nasal-origin deep-source headache (bi yuan type): nasal sinus infection producing frontal pressure and headache; addressed through both the nasal-opening action and the channel-pain relief
• Wind-Damp bi-syndrome joint pain: pair with Cang Zhu, Cao Wu

3. Open and unblock the nasal orifice: Bai Zhi’s aromatic pungent quality disperses nasal mucosal congestion and reduces inflammatory swelling. Modern pharmacology confirms this: Bai Zhi dilates nasal mucosal blood vessels and reduces mucosal oedema. Clinical application: rhinitis (bi yuan, bi qiu) — nasal congestion, copious nasal discharge, loss of smell, frontal pain. The classical standard formula is Cang Er Zi San (Bai Zhi + Cang Er Zi + Xin Yi + Bo He).

4. Dry Damp and stop leucorrhoea: Pungent-warm aromatic-drying nature dries the Damp-turbidity descending to the lower Jiao. For Cold-Damp descending pattern: clear thin copious leucorrhoea; pair with Lu Jiao Shuang, Bai Zhu, and Shan Yao. For Damp-Heat pattern (yellow-viscous-malodorous): pair with Huang Bai and Che Qian Zi to add clearing to the drying.

5. Scatter stagnation, reduce swelling, and drain pus: Bai Zhi can disperse early-stage carbuncle swelling (yong ju) and “eat through” formed pus to facilitate drainage. For early-stage (redness, swelling, heat, pain before suppuration): pair with Jin Yin Hua, Dang Gui, Chuan Shan Jia — as in Xian Fang Huo Ming Yin. For pus-formed but not draining: pair with Ren Shen, Huang Qi to supplement Qi and drive pus out. Also: promotes wound healing and skin tissue regeneration (chang ji fu, run ze yan se — promotes muscle growth and complexion lustre, as the Shen Nong Ben Cao Jing records).

III. Five Classical Formulas

1. Du Liang Wan “Single-Herb Bai Zhi Pill” (Bai Yi Xuan Fang)
Composition: Bai Zhi alone, powdered and formed into honey pills. Taken with tea or Jing Jie decoction. Action: dispel Wind and scatter Cold, relieve headache. Indication: head-Wind dizziness, Wind-Cold headache, Wind-Cold common cold headache, pregnant or post-partum women with Wind-Cold headache. The classical single-herb formula demonstrating Bai Zhi’s headache-relieving power alone.

2. Jiu Wei Qiang Huo Tang “Nine-Herb Notopterygium Decoction” (Ci Shi Nan Zhi)
Composition: Bai Zhi · Qiang Huo · Fang Feng · Xi Xin · Chuan Xiong · Cang Zhu · Huang Qin · Sheng Di · Gan Cao. Action: resolve exterior and scatter Cold, dispel Wind and dry Damp, simultaneously clear interior Heat. Indication: Wind-Cold common cold and Wind-Cold-Damp bi-syndrome; aversion to cold, fever, absence of sweat, headache and body aching. Bai Zhi here contributes the facial-channel pain-relieving action complementing Qiang Huo’s posterior-cranial action.

3. Cang Er Zi San “Xanthium Fruit Powder” (Ji Sheng Fang)
Composition: Bai Zhi · Cang Er Zi · Xin Yi · Bo He. Action: open and unblock the nasal orifice, dispel Wind and relieve pain. Indication: rhinitis and sinusitis (bi yuan, bi qiu) — nasal congestion, copious nasal discharge, frontal pain, olfactory impairment. The classical standard formula for nasal conditions; Bai Zhi and Xin Yi are the two core herbs, with Cang Er Zi strengthening Wind-Damp-dispersal at the nasal orifice and Bo He contributing cooling to prevent over-warming.

4. Xian Fang Huo Ming Yin “Immortals’ Life-Activating Drink” (Jiao Zhu Fu Ren Liang Fang)
Composition: Bai Zhi · Jin Yin Hua · Dang Gui · Chuan Shan Jia · Fang Feng · Chen Pi and others. Action: clear Heat and detoxify, reduce swelling and drain pus, activate Blood and relieve pain. Indication: early-stage carbuncle and abscess with redness, swelling, heat, and pain. Bai Zhi’s scatter-stagnation and drain-pus action is critical here alongside Jin Yin Hua’s detoxification.

5. Chuan Xiong Cha Tiao San “Ligusticum-Tea Adjustment Powder” (He Ji Ju Fang)
Composition: Bai Zhi · Chuan Xiong · Fang Feng · Xi Xin · Bo He · Jing Jie and others. Action: disperse Wind and relieve headache. Indication: exterior Wind pathogen headache regardless of Wind-Cold or Wind-Heat. Bai Zhi specifically targets frontal and supraorbital pain; Chuan Xiong targets temporal and vertex pain — together covering the full cranial pain spectrum.

IV. Four-Herb Differential: Bai Zhi, Qiang Huo, Xi Xin, Gao Ben

V. Modern Pharmacology and Applications

Core chemical constituents: Volatile oils (furfural, methyl cyclodecenone), coumarins (imperatorin, isoimperatorin — the primary bioactive fraction), bai zhi toxin, and sterols.

Documented pharmacological actions:

• Antipyretic, analgesic, and anti-inflammatory: inhibits inflammatory mediators; reduces fever; relieves pain; supports the classical resolve-Wind and relieve-pain actions
• Antibacterial and antiviral: inhibits Staphylococcus aureus, pneumococcus, and influenza virus; supports the carbuncle-draining and surface-pathogen actions
• Nasal decongestant: dilates nasal mucosal blood vessels; reduces mucosal oedema; directly supports the classical open-nasal-orifice action
• Additional: antioxidant, anti-fatigue, gastrointestinal regulatory, inhibition of fat cell synthesis, central nervous system excitation (aromatic component), and mild antihypertensive effects

Modern applications: Tong Qiao Bi Yan Pian and Biao Shi Gan Mao Ke Li (rhinitis and common cold patent formulas); Tian Ma Tou Tong Pian and Feng Shi Ding Pian (pain formulas); dermatology (eczema, dermatitis, acne — topical wash or ointment); beauty applications (Bai Zhi + Bai Zhu + Bai Shao face mask for brightening and spot-fading, from the classical cosmetic use recorded in Shen Nong Ben Cao Jing).

VI. Dosage and Safety

Dosage: internal decoction 3–10g; do not exceed: dizziness, nausea, and discomfort may occur with overdose. External use: appropriate amount, ground to powder and applied, or decocted as a wash.

Contraindications:

• Yin deficiency-Blood Heat: tidal flushing, night sweats, dry mouth and throat, red tongue with scant coating, haemorrhagic tendency — Bai Zhi’s pungent-warm aromatic-drying nature further depletes Yin fluids and generates Heat; contraindicated
• Pregnancy: use under specialist supervision; pungent-warm penetrating nature may affect foetal Qi
• Wind-Heat common cold alone: Bai Zhi is warm; for pure Wind-Heat (high fever, sore throat, yellow phlegm) without Cold component, use with clearing herbs (Sang Ye, Ju Hua, Lian Qiao); do not use Bai Zhi alone as it may worsen Heat
• Classical incompatibility: Bai Zhi e (is averse to) Xuan Fu Hua — do not combine; may reduce efficacy
• Long-term use: may damage Spleen-Stomach Yang with prolonged use; those with Spleen-Stomach weakness should use with caution