Herb Root (根 gēn)

Cong Xu

Green onion root · 葱须

Allii Fistulosi Radix

Also known as: Cōng Gēn (葱根)

Green onion root is the fibrous root of the common green onion, used in Chinese medicine to fight off early-stage colds by inducing sweating and relieving nasal congestion. It is also applied topically to treat frostbite, hemorrhoids, and skin sores due to its warming and stasis-dispersing properties.

Category Warm, acrid herbs that release the Exterior (辛温解表药) Substances for external application (外用药)
Therapeutic focus Cold and flu Nasal congestion and sinus relief Skin health Circulation

TCM Properties

Temperature

Warm

Taste

Acrid / Pungent (辛 xīn)

Channels entered

Lungs

Parts used

Root (根 gēn)

Educational content • Consult qualified TCM practitioners for diagnosis and treatment

What This Herb Does

Every herb has a specific set of actions — here's what Cong Xu does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Cong Xu is primarily used to support these areas of health:

Cold and flu Nasal congestion and sinus relief Skin health Circulation

TCM Actions

In TCM terminology, these are the specific therapeutic actions that Cong Xu performs to restore balance in the body:

Releases the exterior and dispels wind-cold Induces sweating Unblocks yang and disperses cold Detoxifies Disperses blood stasis

How these actions work

'Releases the exterior and dispels wind-cold' means this herb helps the body fight off the early stages of a cold or flu by pushing out the pathogenic factors through sweating. 'Induces sweating' is a key mechanism for eliminating exterior wind-cold. 'Unblocks yang and disperses cold' refers to its ability to warm the channels and improve circulation, which is why it helps with cold extremities and nasal congestion. 'Detoxifies' and 'disperses blood stasis' explain its use in treating skin sores, hemorrhoids, and frostbite, where it clears local toxins and promotes healing by moving stagnant blood.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony. Cong Xu is used to help correct these specific patterns.

Why Cong Xu addresses this pattern

Cōng Xū's acrid-warm nature releases the exterior and dispels Wind-Cold, entering the Lung channel to relieve external symptoms. It promotes sweating to expel pathogens, making it effective for the classic presentation of Wind-Cold with chills, fever, headache, and nasal congestion.

A practitioner would look for one or more of these signs

Chills
Fever
Headaches

Headache

Nasal Congestion

Nasal congestion

Anhidrosis

Absence of sweating

Commonly Used For

These are conditions where Cong Xu is frequently used — but only when they arise from the specific patterns it addresses, not in all cases

Arises from: Wind-Cold

TCM Interpretation

In TCM, the common cold is typically seen as an invasion of external Wind-Cold, which obstructs the Lung's diffusing function and the body's defensive Qi, leading to symptoms like chills, fever, headache, and nasal congestion.

Why Cong Xu Helps

Cōng Xū's acrid-warm nature releases the exterior, induces sweating, and expels Wind-Cold, directly countering the pathogenic factors at the surface and restoring the Lung's normal function.

Also commonly used for

Influenza

Used at onset to dispel wind-cold and reduce fever and body aches.

Pharyngitis

Powder blown onto throat sores to detoxify and promote healing.

Sinusitis

Relieves nasal congestion and sinus pressure by opening the nasal passages.

Herb Properties

Every herb has an inherent temperature, taste, and affinity for specific channels — these properties determine how it interacts with the body

Temperature

Warm

Taste

Acrid / Pungent (辛 xīn)

Channels Entered

Lungs

Parts Used

Root (根 gēn)

Dosage & Preparation

These are general dosage guidelines for Cong Xu — always follow your practitioner's recommendation, as dosages vary based on the formula and your individual condition

Standard dosage

3-10g

Maximum dosage

Generally not exceeding 15g in decoction; larger doses may cause excessive sweating and fatigue.

Dosage notes

For mild wind-cold invasion with chills and nasal congestion, 3-6g decocted; for more pronounced symptoms, up to 10g. For external use as a wash for hemorrhoids or frostbite, fresh Cong Xu may be used in larger amounts (60-120g) and decocted for topical application. Avoid prolonged internal use to prevent Qi depletion.

Preparation

Rinse thoroughly in several changes of water to remove sand and soil lodged in the rootlets. Decoct for 10-15 minutes; prolonged boiling may dissipate the volatile aromatic compounds responsible for its diaphoretic effect.

Processing Methods

In TCM, the same herb can be prepared in different ways to change its effects — here's how processing alters what Cong Xu does

Processing method

Fresh rootlets are washed, drained, and sun-dried or dried at low temperature.

How it changes properties

Drying reduces moisture, concentrates active constituents, and preserves the acrid and warm nature. The dried form has a slightly more focused dispersing action.

When to use this form

Standard form for internal decoctions and medicinal preparations.

Common Herb Pairs

These ingredients are traditionally combined with Cong Xu for enhanced therapeutic effect

Sheng Jiang
Sheng Jiang 1:1, e.g., Cōng Xū 10g, Shēng Jiāng 10g

Both acrid-warm, they synergistically release the exterior and dispel wind-cold, with Sheng Jiang warming the middle and stopping vomiting.

When to use: Early-stage wind-cold with chills, headache, nasal congestion, and possible nausea or vomiting.

Dan Dou Chi
Dan Dou Chi 1:1, as in Cōng Chǐ Tāng

Cōng Xū releases exterior and unblocks yang; Dàn Dòu Chǐ releases exterior and relieves restlessness. Together they treat wind-cold with mild heat or irritability.

When to use: Wind-cold exterior pattern with slight fever, irritability, and chest oppression.

Gui Zhi
Gui Zhi 1:1

Cōng Xū unblocks yang and dispels cold; Guì Zhī warms the channels and promotes sweating. Together they warm the channels and dispel cold, especially for cold extremities.

When to use: Wind-cold with cold limbs, or cold obstruction in the channels.

Comparable Ingredients

These ingredients have overlapping uses — here's how to tell them apart

Cong Bai
Cong Xu vs Cong Bai

Both release exterior and dispel wind-cold, but Cōng Bái is more commonly used and enters Lung and Stomach channels, while Cōng Xū is milder and also has stasis-dispersing properties, making it suitable for topical use on sores and frostbite.

Sheng Jiang
Cong Xu vs Sheng Jiang

Both are acrid-warm exterior-releasers, but Shēng Jiāng is stronger at warming the middle and stopping vomiting, while Cōng Xū is better at unblocking yang and treating nasal congestion.

Therapeutic Substitutes

Legitimate clinical replacements when Cong Xu is unavailable, restricted, or contraindicated

Cong Bai

Cong Bai
Cong Bai 葱白
Scallion Bulb

Covers: Covers Cōng Xū's exterior-releasing and wind-cold dispelling actions, as well as its ability to unblock yang and relieve nasal congestion.

Does not cover: Cōng Bái is slightly less effective for dispersing blood stasis and treating hemorrhoids or frostbite topically; its actions are more focused on the exterior and stomach.

Use when: When Cōng Xū is not available, Cōng Bái can be used in the same dosage range (3-10g).

Identity & Adulterants

Related species and common adulterations to be aware of when sourcing Cong Xu

Cong Xu may be confused with rootlets of other Allium species such as garlic (Allium sativum) or Chinese chive (Allium tuberosum). Authentic Cong Xu has the distinctive green-onion scent and a milder taste; garlic rootlets have a strong garlic odor, and chive rootlets are thinner and lack the typical scallion smell. It may also be adulterated with rootlets of other non-Allium plants, which lack the pungent onion odor.

Educational content — always consult a qualified healthcare provider or TCM practitioner before using any herb.

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Cong Xu

Non-toxic

Cong Xu is non-toxic at normal doses. As a member of the Allium family, excessive raw consumption may cause gastrointestinal irritation in sensitive individuals. No specific toxic components have been identified.

Contraindications

Situations where Cong Xu should not be used or requires extra caution

Avoid

Contraindicated in patients with yin deficiency and internal heat (阴虚火旺). The warm and acrid nature may aggravate dryness and fire.

Caution

Use with caution in patients with spontaneous sweating due to exterior deficiency (表虚自汗). Its dispersing action may further deplete qi and promote sweating.

Caution

May cause allergic reactions in individuals sensitive to Allium species.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Cong Xu is generally considered safe during pregnancy when used in normal culinary amounts. As a warm, acrid herb that promotes sweating and disperses exterior pathogens, large medicinal doses should be used with caution, especially in pregnant women with signs of yin deficiency, heat, or threatened miscarriage. Consultation with a qualified practitioner is recommended before using medicinal doses during pregnancy.

Breastfeeding

No adverse effects have been reported. Cong Xu is considered safe for breastfeeding mothers when consumed in food amounts. Its mild nature is unlikely to transfer significant effects through breast milk. Standard medicinal doses are likely safe, but caution is advised due to limited data.

Children

Cong Xu can be used in children for early-stage wind-cold common cold. For young children (3-6 years), a dose of 1-3g decocted as a weak tea is appropriate. For older children, 3-5g may be used. The decoction should not be overly strong, and treatment should be short-term (1-2 days). Ensure the child does not have signs of heat (fever, red tongue). Avoid in infants under 1 year without professional guidance.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Cong Xu

Due to its mild blood-thinning effect from sulfur compounds, high doses of Cong Xu may theoretically potentiate anticoagulant medications such as warfarin, though clinical evidence is lacking. Caution is advised when combining large amounts with antiplatelet drugs (e.g., aspirin, clopidogrel).

Dietary Advice

Foods and dietary considerations when taking Cong Xu

When taking Cong Xu for wind-cold conditions, avoid cold, raw, and greasy foods that may interfere with the exterior-releasing action. It is traditionally taken with warm broth or congee to enhance sweating without depleting Qi.

Botanical Description

Physical characteristics and morphology of the Cong Xu source plant

Cong Xu is derived from the scallion plant, Allium fistulosum L., a perennial herbaceous crop of the Liliaceae (or Alliaceae) family. It grows 30–100 cm tall, forming a cylindrical, hollow stem and long, tubular, hollow leaves. The base swells into a white, fleshy stalk (the commonly eaten portion). The root system is fibrous, producing numerous fine, white to light brown rootlets that can extend 10–30 cm into the soil. Small, greenish-white flowers appear in spherical umbels in the second year of growth. The plant is cultivated worldwide in temperate regions, particularly in China, Japan, Korea, and Europe, preferring well-drained, loamy soil and full sun.

Sourcing & Harvesting

Where Cong Xu is sourced, when it's harvested or collected, and how to assess quality

Harvesting season

Autumn, when the plant is fully mature; rootlets are collected after the scallion bulbs are harvested.

Primary growing regions

Widely cultivated throughout China. Shandong Province, particularly the Zhangqiu area, is renowned for producing large, flavorful scallions with abundant rootlets of good medicinal quality.

Quality indicators

High-quality Cong Xu consists of numerous, fine, pliable rootlets with a uniform whitish to pale brown color and a strong, characteristic onion aroma. It should be free from mud, sand, mold, and insect damage. Fresh rootlets are slightly moist and flexible; dried ones become brittle. Inferior quality product appears dark, woody, or has lost its pungent smell.

Classical Texts

Key passages from the classical Chinese medical texts that describe Cong Xu and its therapeutic uses

《名医别录》 (Míng Yī Bié Lù) – Records of Famous Physicians (circa 500 CE):
“主伤寒头痛。” (Treats headache due to cold damage.)

孟诜 (Mèng Shēn) – Tang Dynasty (7th century):
“通气。” (Promotes the circulation of Qi.)

《日华子本草》 (Rì Huá Zǐ Běn Cǎo) – Ri Hua Zi's Materia Medica (10th century):
“杀一切鱼肉毒。” (Neutralizes all poisons from fish and meat.)

《本草纲目》 (Běn Cǎo Gāng Mù) – Compendium of Materia Medica (1578), Li Shizhen:
“疗饱食房劳，便血肠澼成痔。” (Treats anal bleeding and intestinal afflictions progressing to hemorrhoids, caused by overeating and sexual exertion.)

《医准》 (Yī Zhǔn) – Medical Standards (Song Dynasty):
For treating throat sores, Cong Xu powder is blown into the affected area together with danfan (chalcanthite).

Historical Context

The history and evolution of Cong Xu's use in Chinese medicine over the centuries

The scallion has been cultivated in China for over 3,000 years. Ancient texts recognized different parts of the scallion for distinct medicinal properties: the white stalk (Cong Bai) for its strong pungency and yang-unblocking ability, the green leaves (Cong Ye) for dispersing wind-heat, and the root fibers (Cong Xu) as a gentle diaphoretic especially suited to the early stages of common cold. Despite being often discarded as kitchen waste, Cong Xu was recorded in many classical formularies for treating wind-cold headache and hemorrhoids. Li Shizhen in the Bencao Gangmu noted its use for bleeding hemorrhoids and intestinal ailments. Folk medicine employed Cong Xu decoction combined with fermented soybeans (Dan Dou Chi) as a warm remedy for febrile chills and fatigue. The name Cong Xu (葱须) literally means “scallion's beard,” describing the numerous slender root fibers. In modern times, research has validated its higher concentration of polyphenols and polysaccharides compared to the aerial parts, giving it notable antioxidant and immune-modulating properties.