Bai Mao Gen (白茅根): Cogongrass Rhizome in TCM — Cooling Blood and Stopping Bleeding

What Is Bai Mao Gen?

Bai Mao Gen (白茅根), meaning “White Hair Root,” is the dried rhizome and root of Imperata cylindrica (Cogongrass). The name describes the white, silky, hair-like fibers that cover the creeping underground stems. This common grass is considered a weed by farmers worldwide, but in Chinese medicine, its roots are a valuable remedy for cooling blood and stopping bleeding.

Bai Mao Gen is one of the safest and most gentle heat-clearing herbs in the TCM materia medica. Its sweet, cold nature makes it suitable for children, the elderly, and long-term use — qualities that earned it a place in household medicine across China for centuries. Fresh juice from the root is a traditional summertime cooling drink for children with heat symptoms.

Basic Information

Property	Details
Chinese name	白茅根 (Bái Máo Gēn)
English name	Cogongrass Rhizome / Lalang Grass Root
Pharmaceutical name	Imperatae Rhizoma
Source	Rhizome of Imperata cylindrica
Nature	Cold
Flavor	Sweet
Meridian affinity	Lung, Stomach, Bladder
Dosage	15–30g dried; 30–60g fresh

TCM Properties and Actions

Primary Actions

1. Cools blood and stops bleeding (凉血止血) — the foremost action
2. Clears heat and promotes urination (清热利尿) — for edema and urinary heat
3. Clears Lung and Stomach heat (清肺胃热) — for cough with heat, vomiting
4. Generates fluids (生津) — for thirst from heat

Why Bai Mao Gen Is Special

Among blood-cooling, bleeding-stopping herbs, Bai Mao Gen is unique because:

• Sweet and cold — it cools without being bitter or harsh
• Stops bleeding without causing stasis — it doesn’t congeal blood
• Safe for children — one of the few heat-clearing herbs routinely given to children
• Dual action — cools blood AND promotes urination to drain heat out
• Fresh and dried forms have different strengths (fresh generates more fluids)

Clinical Applications

1. Nosebleeds (鼻衄)

Bai Mao Gen is one of the best herbs for nosebleeds in TCM:

• Spontaneous nosebleeds, especially in children
• Nosebleeds from heat, dry weather, or after fever
• Often the first herb chosen for this condition
• Simple tea: 30g fresh Bai Mao Gen in boiling water

2. Blood in the Urine (血淋/尿血)

• Hematuria (blood in urine) from bladder heat
• Urinary tract infections with bleeding
• Painful, urgent urination with red-tinged urine
• Often combined with Xiao Ji, Ou Jie, Che Qian Zi

3. Coughing Blood (咳血)

• Blood-tinged sputum from Lung heat
• Tuberculosis-type patterns with dry cough and blood
• Often combined with Bai Ji, Ce Bai Ye, Ou Jie

4. Vomiting Blood (吐血)

• Blood in vomit from Stomach heat
• Gastric bleeding with heat patterns
• Often combined with Ou Jie, Ce Bai Ye

5. Edema and Urinary Difficulty (水肿小便不利)

• Edema, especially in the lower body
• Difficult or scanty urination
• Nephritic edema (edema from kidney inflammation)
• The herb promotes urination while also cooling inflammation
• Often combined with Fu Ling, Ze Xie, Che Qian Zi

6. Thirst and Dry Mouth from Heat (热病口渴)

• Fever-related dehydration
• Summer heat with excessive thirst
• The sweet, cold nature generates fluids
• Fresh juice is particularly effective

Bai Mao Gen vs. Other Blood-Cooling Herbs

Feature	Bai Mao Gen	Di Yu	Ce Bai Ye	Bai Ji
Temperature	Cold	Slightly cold	Cool	Neutral
Flavor	Sweet	Bitter, sour	Bitter, astringent	Bitter, sweet
Strength	Gentle, safe	Stronger astringent	Moderate	Strong tissue healer
Best for	Nosebleeds, UTI bleeding	Heavy bleeding	Coughing blood	Lung/Stomach ulcers
Special property	Also promotes urination	Also heals burns	Also cools Lung	Also promotes tissue repair
Safety	Very safe, even for children	Good	Good	Good

Classic Combinations

For Nosebleeds

Herb	Amount	Purpose
Bai Mao Gen	30g	Cools blood, stops bleeding
Ou Jie (Lotus node)	15g	Stops bleeding, especially from upper body
Sheng Di Huang	12g	Cools blood, nourishes Yin

For Blood in Urine

Herb	Amount	Purpose
Bai Mao Gen	30g	Cools blood, promotes urination
Xiao Ji (Small Thistle)	15g	Cools blood, stops urinary bleeding
Che Qian Zi	10g	Promotes urination, drains heat

For Edema

Herb	Amount	Purpose
Bai Mao Gen	30g	Clears heat, promotes urination
Fu Ling	15g	Drains dampness, strengthens Spleen
Ze Xie	10g	Promotes urination, drains heat

Preparation and Usage

As Decoction (煎药)

• Standard dose: 15–30g dried; 30–60g fresh
• Dried form: cook 15–20 minutes
• Fresh form: can be juiced directly (most potent)
• For bleeding: do not overcook — add toward the end

Fresh Juice (鲜汁)

The most potent form:

1. Wash fresh Bai Mao Gen thoroughly
2. Crush or blend with a small amount of water
3. Strain the juice
4. Drink 30–60ml, 2–3 times daily
5. Especially effective for nosebleeds and fever thirst

As Tea (代茶饮)

• 15–30g dried Bai Mao Gen
• Steep in boiling water for 15 minutes
• Drink throughout the day
• A traditional summer cooling drink in rural China

Modern Research

Contemporary studies on Bai Mao Gen have revealed:

• Hemostatic — promotes blood clotting in minor bleeding
• Diuretic — increases urine output
• Anti-inflammatory — reduces inflammatory markers
• Antipyretic — helps reduce fever
• Hepatoprotective — some protective effects on the liver
• Antibacterial — activity against certain urinary pathogens

Key compounds include cylindrin, imperanene, arundoin, and various triterpenoids.

Notable Finding

Research confirms that fresh Bai Mao Gen has significantly stronger diuretic and anti-inflammatory effects than the dried form — validating the traditional preference for fresh herb in acute conditions.

Precautions

Situation	Guidance
Spleen-Stomach cold deficiency	Use cautiously — cold nature may cause loose stools
Bleeding from cold patterns	Not suitable — this is for heat-type bleeding
Severe anemia	Does not nourish blood directly; combine with blood tonics

Key Takeaways

• Bai Mao Gen (Cogongrass rhizome) is the gentlest blood-cooling, bleeding-stopping herb in TCM
• Its sweet, cold nature makes it safe for children and the elderly
• Best known for treating nosebleeds, blood in urine, and edema
• Dual action: cools blood AND promotes urination to drain heat
• Fresh form is more potent than dried — fresh juice is traditional for acute bleeding
• A common roadside grass with remarkable medicinal value
• Modern research confirms hemostatic, diuretic, and anti-inflammatory properties

Disclaimer: This article is for educational purposes only. Consult a licensed TCM practitioner before using Bai Mao Gen or any herbal preparation.

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