Herb Seed (种子 zhǒng zǐ / 子 zǐ / 仁 rén)

Huo Ma Ren

Hemp seed · 火麻仁

Cannabis sativa L. · Fructus Cannabis

Also known as: Má Zǐ Rén (麻子仁), Dà Má Rén (大麻仁), Má Rén (麻仁),

Huo Ma Ren (Hemp seed) plant

Images shown are for educational purposes only

Hemp seed is a gentle, oil-rich seed used in Chinese medicine primarily as a natural laxative for dry, hard stools. It is especially suited for elderly people, new mothers, or anyone weakened by illness whose body fluids have become depleted, leading to constipation. It also has mild nourishing properties that help replenish the body's moisture without being harsh on the digestive system.

Category Moist laxatives (润下药)
Therapeutic focus Digestive Health Constipation Relief Cardiovascular Health Skin Health

TCM Properties

Temperature

Neutral

Taste

Sweet (甘 gān)

Channels entered

Spleen, Stomach, Large Intestine

Parts used

Seed (种子 zhǒng zǐ / 子 zǐ / 仁 rén)

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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 Huo Ma Ren does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Huo Ma Ren is primarily used to support these areas of health:

Digestive Health Constipation Relief Cardiovascular Health Skin Health

TCM Actions

In TCM terminology, these are the specific therapeutic actions that Huo Ma Ren performs to restore balance in the body:

Moistens the Intestines and Unblocks the Bowels Nourishes Yin Promotes Urination Invigorates Blood and Dispels Stasis

How these actions work

'Moistens the intestines and unblocks the bowels' is the primary action of Huǒ Má Rén. The seed is rich in oils that lubricate the intestinal walls, helping dry, hardened stool pass more easily. This is not a forceful purging action like that of Dà Huáng (rhubarb), but rather a gentle, nourishing approach to constipation. It is best suited for people whose constipation comes from a lack of body fluids, such as the elderly, those recovering from illness, or new mothers after childbirth.

'Nourishes Yin' refers to the herb's mild ability to replenish the body's moistening fluids. Because it is sweet and rich in fats, it helps restore moisture in the intestines and throughout the body. This makes it helpful not just for constipation but also for mild Yin Deficiency with dryness symptoms such as a dry mouth or dry skin.

'Promotes urination' and 'Invigorates Blood' are secondary, classical actions recorded in older texts like the Biè Lù (別錄). These describe the seed's traditional use for conditions such as painful urination (hot-type urinary difficulty) and for promoting blood circulation after childbirth. These actions are less commonly applied in modern clinical practice compared to the primary laxative function.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony. Huo Ma Ren is used to help correct these specific patterns.

Why Huo Ma Ren addresses this pattern

Intestinal Dryness occurs when the Large Intestine lacks sufficient fluids to move stool through the bowel. Huǒ Má Rén directly addresses this with its sweet, oil-rich nature. The abundant fatty oils lubricate the intestinal lining, while its sweet flavour gently nourishes and replenishes the fluids that are missing. Because it is neutral in temperature, it moistens without adding Heat or Cold, making it safe for a wide range of patients including the elderly, postpartum women, and those recovering from febrile illness.

A practitioner would look for one or more of these signs

Constipation

Dry, hard stools that are difficult to pass

Dry Mouth

Dryness of the mouth and throat from fluid depletion

Abdominal Distention

Mild abdominal fullness with infrequent bowel movements

Commonly Used For

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

Arises from: Intestinal Dryness Blood Deficiency Heat in the Large Intestine

TCM Interpretation

TCM understands chronic constipation not as a single disease but as a symptom arising from different underlying imbalances. The most relevant patterns for Huǒ Má Rén involve a lack of moistening fluids in the Large Intestine. This can happen because the body's Blood and Yin are depleted (common in elderly people, after childbirth, or after prolonged illness), or because Heat in the Stomach and Intestines has scorched away the fluids. In either case, the intestines become like a dry riverbed with insufficient water to carry things downstream. The Spleen, which normally distributes fluids throughout the body, may be 'restrained' by excessive Stomach Heat, sending fluids to the Bladder instead of the Intestines.

Why Huo Ma Ren Helps

Huǒ Má Rén is ideally suited for constipation from dryness because its oil-rich seeds directly replenish the lubrication the intestines need. Its sweet flavour gently nourishes depleted fluids without being cloying, and its neutral temperature means it won't worsen either Heat or Cold patterns. Unlike harsh purgatives, it works by moistening rather than forcing, making it safe for the very people most prone to this type of constipation: the elderly, new mothers, and those weakened by illness. In the classical formula Má Zǐ Rén Wán, it serves as the chief herb, working alongside mild purgatives to restore normal bowel function without depleting the body further.

Also commonly used for

High Cholesterol

Modern research suggests lipid-lowering effects from its rich essential fatty acid content

Hypertension

Animal studies show mild blood-pressure lowering effect

Dark Skin

Topical use of the oil for skin dryness and cracking

Atherosclerosis

Preliminary evidence of anti-atherosclerotic activity via lipid modulation

Herb Properties

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

Temperature

Neutral

Taste

Sweet (甘 gān)

Channels Entered

Spleen Stomach Large Intestine

Parts Used

Seed (种子 zhǒng zǐ / 子 zǐ / 仁 rén)

Dosage & Preparation

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

Standard dosage

10-15g

Maximum dosage

Up to 30g in severe constipation under practitioner supervision. Do not exceed 60g as toxic reactions (nausea, confusion, dilated pupils) have been reported at doses of 60-120g.

Dosage notes

The standard decoction dose is 10-15g. For mild constipation or as a dietary supplement, 10g is usually sufficient. For more stubborn intestinal dryness constipation in the elderly or postpartum women, doses of 15-30g may be used. Because the active oils are not fully water-soluble, the herb is traditionally considered more effective in pill form (such as Ma Zi Ren Wan) than in decoction. When used in decoction, the seeds should be lightly crushed before boiling to release the oils. Dry-frying (chao) enhances the nourishing properties and reduces the slippery laxative effect, which is preferred when the herb is used more for supplementation than for purgation.

Preparation

The seeds should be lightly crushed or cracked (打碎) before adding to the decoction pot, as the intact seed coat prevents the medicinal oils from being fully extracted into the liquid. This is noted in classical prescription instructions. No other special decoction handling (such as decocting first or adding late) is required.

Processing Methods

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

Processing method

The clean hemp seeds are dry-fried over a gentle flame (文火) until they turn slightly yellow and release an aromatic fragrance, then removed and cooled. They are crushed before use.

How it changes properties

The temperature and taste remain essentially unchanged (still sweet and neutral). Dry-frying does not significantly alter the herb's core actions. Its main purpose is to improve the decoction extraction rate, making the active oils easier to dissolve when boiled. Some classical sources note that dry-frying slightly enhances the nourishing quality while mildly reducing the slippery, laxative strength. The Ben Cao Qiu Zhen states that the raw form is more 'moving' (promotes blood and urination) while the processed form is more 'guarding' (nourishing and stabilizing).

When to use this form

Use the dry-fried form when preparing decoctions (as opposed to pills), since frying cracks the shell and improves extraction. Also preferred when a slightly gentler laxative effect is desired, or when focusing more on the herb's nourishing rather than its laxative properties.

Common Herb Pairs

These ingredients are traditionally combined with Huo Ma Ren for enhanced therapeutic effect

Bai Shao
Bai Shao Huǒ Má Rén 10-15g : Bái Sháo 10g

Huǒ Má Rén moistens and lubricates the intestines with its oils, while Bái Sháo (White Peony root) nourishes Yin and Blood and softens the Liver. Together, they address constipation that arises from both fluid depletion and Blood Deficiency, providing lubrication and nourishment simultaneously.

When to use: Constipation in people who are Blood-deficient or Yin-deficient, particularly elderly or postpartum women with dry stools, pale complexion, and a dry tongue.

Xing Ren
Xing Ren 1:1 (Huǒ Má Rén 10g : Xìng Rén 10g)

Huǒ Má Rén moistens the intestines from below while Xìng Rén (Apricot seed) descends Lung Qi from above to help drive stool downward. The Lung and Large Intestine are paired organs in TCM, so this combination works on both the upper driving force and the lower lubrication needed for bowel movement.

When to use: Dry constipation accompanied by Lung dryness symptoms like a dry cough or shortness of breath, or when the constipation is related to poor downward movement of Qi.

Da Huang
Da Huang Huǒ Má Rén 20g : Dà Huáng 12g (as in Má Zǐ Rén Wán proportions)

Huǒ Má Rén provides gentle lubrication and fluid nourishment, while Dà Huáng (Rhubarb) actively purges Heat and drives stool downward. Together they form a 'moisten-and-drain' combination that clears intestinal Heat-dryness without being overly harsh. This is the core mechanism of Má Zǐ Rén Wán.

When to use: Constipation from Stomach and Intestinal Heat with dry, hard stools and frequent urination. The Huǒ Má Rén softens what Dà Huáng pushes out, and prevents the purgative from depleting fluids further.

Bai Zi Ren
Bai Zi Ren 1:1 (Huǒ Má Rén 10g : Bǎi Zǐ Rén 10g)

Both are oil-rich seeds that moisten the intestines, but they nourish different organ systems. Huǒ Má Rén focuses on the Spleen, Stomach, and Large Intestine, while Bǎi Zǐ Rén (Platycladus seed) also nourishes the Heart and calms the spirit. Together they provide a broader moistening and nourishing effect.

When to use: Constipation in elderly or debilitated patients who also have insomnia, anxiety, or palpitations alongside their dry stools.

Key Formulas

These well-known formulas feature Huo Ma Ren in a prominent role

Ma Zi Ren Wan 麻子仁丸 King

The definitive formula for Huǒ Má Rén. From the Shāng Hán Lùn, this pill treats the 'Spleen-restrained' (pí yuē) pattern of constipation with dry stools and frequent urination. Huǒ Má Rén serves as King herb at the largest dose, providing the core moistening and lubricating action, while Dà Huáng, Zhǐ Shí, and Hòu Pò (essentially Xiǎo Chéng Qì Tāng) gently clear Heat and move Qi downward. This formula perfectly showcases the herb's ability to moisten the intestines without harsh purgation.

Run Chang Wan 潤腸丸 Deputy

A formula for Blood-Deficiency constipation, combining Huǒ Má Rén with Dāng Guī, Shēng Dì Huáng, Táo Rén, and Zhǐ Qiào. Huǒ Má Rén serves as Deputy, contributing intestinal lubrication that complements the Blood-nourishing and Blood-moving herbs. This highlights its clinical role in treating constipation rooted in Blood Deficiency rather than Heat.

Zhi Gancao Tang 炙甘草湯 Assistant

Also from the Shāng Hán Lùn, this formula treats Qi and Blood Deficiency of the Heart with irregular pulse and palpitations. Huǒ Má Rén plays an Assistant role, contributing its moistening and nourishing properties to help replenish Yin and Blood alongside Shēng Dì Huáng, Mài Dōng, and Ē Jiāo. This demonstrates the herb's secondary function as a Yin-nourishing substance beyond its primary laxative use.

Comparable Ingredients

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

Yu Li Ren
Huo Ma Ren vs Yu Li Ren

Both moisten the intestines to relieve constipation, but Huǒ Má Rén is gentler, more nourishing, and better suited for Deficiency-type constipation in the elderly, postpartum women, or debilitated patients. Yù Lǐ Rén (Bush Cherry seed) has a stronger laxative action and also promotes urination to reduce edema, making it more appropriate for Excess-type constipation or when fluid retention is also present.

Gua Lou Ren
Huo Ma Ren vs Gua Lou Ren

Both are oily seeds that moisten the intestines. Guā Lóu Rén (Trichosanthes seed) is cold in nature and also clears Heat and transforms Phlegm in the Lungs, so it is better suited when constipation is accompanied by Lung-Heat with thick, sticky phlegm and cough. Huǒ Má Rén is neutral and has no Phlegm-transforming action, but is gentler and better for purely dry, fluid-deficient constipation without significant Heat or Phlegm.

Rou Cong Rong
Huo Ma Ren vs Rou Cong Rong

Both treat constipation in elderly patients, but through very different mechanisms. Huǒ Má Rén lubricates the intestines with its oils and is neutral in temperature, appropriate for dryness from fluid or Blood Deficiency. Ròu Cōng Róng (Cistanche) is warm and works by warming Kidney Yáng and supplementing Essence, making it the better choice when constipation is due to Kidney Yáng Deficiency with cold signs like cold limbs and sore lower back.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing Huo Ma Ren

Huo Ma Ren (Cannabis sativa seed) can be confused with Hu Ma Ren (胡麻仁, Sesame/Sesamum indicum seed, also called black sesame). This confusion has a long history and even affects interpretation of classical formulas such as Zhi Gan Cao Tang, where scholars debate whether the original 'ma ren' referred to hemp seed or sesame seed. The two herbs have different actions: Huo Ma Ren is primarily a lubricating laxative, while Hu Ma Ren (sesame) mainly nourishes Liver and Kidney, supplements essence, and has milder bowel-moistening effects. Yu Li Ren (郁李仁, Prunus seed) is sometimes mentioned alongside Huo Ma Ren as a similar laxative herb, but Yu Li Ren is stronger, also promotes urination, and is more suited to Excess-type conditions. Quality-wise, seeds that still retain their hard outer shell or that have been heat-treated to prevent germination (common in imports) should be differentiated from raw medicinal-grade stock.

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

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Huo Ma Ren

Non-toxic

The seed kernel (ren) itself is classified as non-toxic in the Chinese Pharmacopoeia and was described as such in the Shen Nong Ben Cao Jing. However, the outer shell contains trace amounts of tetrahydrocannabinol (THC) and related cannabinoids. The Ben Cao Gang Mu states clearly that "the shell is toxic, but the kernel is non-toxic." When consumed in large amounts with the shell (60-120g of roasted seeds), toxic reactions can occur within 1-2 hours, including nausea, vomiting, diarrhea, limb numbness, agitation, mental confusion, dilated pupils, and in severe cases coma. These symptoms resolve within 1-2 days with supportive care (gastric lavage, fluid replacement) and no fatalities have been reported. At standard medicinal doses of 10-15g of the shelled kernel, no adverse reactions occur. Processing by removing the outer shell and light dry-frying (chao) further ensures safety.

Contraindications

Situations where Huo Ma Ren should not be used or requires extra caution

Caution

Spleen deficiency with loose stools (脾虚便溏). Huo Ma Ren's lubricating, bowel-moistening action can worsen diarrhea and loose stools in people with weak digestion.

Caution

Kidney deficiency with spermatorrhea or impotence. The slippery, descending nature of this herb may aggravate loss of seminal essence in men with Kidney Qi insufficiency.

Caution

Excessive leukorrhea (带下病). Classical sources such as the Yin Shi Xu Zhi (饮食须知) warn that excessive consumption in women may provoke or worsen vaginal discharge conditions.

Avoid

Known allergy or hypersensitivity to hemp seeds or Cannabis sativa products.

Avoid

Overdose. Consuming large quantities (over 60g of roasted seeds) can cause toxic reactions including nausea, vomiting, diarrhea, limb numbness, confusion, dilated pupils, and even coma. Must be used within standard dosage range.

Classical Incompatibilities

Traditional Chinese pharmacological incompatibilities — herbs or substances to avoid combining with Huo Ma Ren

Huo Ma Ren does not appear on the Eighteen Incompatibilities (十八反) or Nineteen Mutual Fears (十九畏) lists. However, the Ben Cao Jing Ji Zhu by Tao Hongjing records: "It fears Mu Li (牡蛎, Oyster Shell) and Bai Wei (白薇, Cynanchum root), and is averse to Fu Ling (茯苓, Poria)." These are traditional incompatibilities specific to this herb that should be respected in clinical practice.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Use with caution during pregnancy. Classical texts including the Ben Cao Cong Xin list pregnancy as a contraindication. Huo Ma Ren's lubricating, downward-moving properties could theoretically stimulate the bowel excessively and affect the uterus. Some classical sources (Ri Hua Zi Ben Cao) actually listed it for promoting labour and treating difficult delivery, which underscores that it has a recognized action on the uterus and should be avoided in early and mid-pregnancy. If constipation treatment is needed during late pregnancy, it should only be used under practitioner supervision at conservative doses.

Breastfeeding

Generally considered compatible with breastfeeding at standard doses. Classical texts (such as the Ming Yi Bie Lu and Ri Hua Zi Ben Cao) actually note that Huo Ma Ren can promote lactation (下乳). The seed kernel contains nutritious fatty acids and protein. However, there are theoretical concerns about trace cannabinoid content passing into breast milk, particularly if the outer shell has not been properly removed. Nursing mothers should use only properly processed (dehulled) seeds at standard doses. Excessive consumption should be avoided as it may cause loose stools in both mother and infant.

Children

Huo Ma Ren can be used in paediatric practice for constipation, typically at reduced doses proportional to age and body weight (roughly one-third to one-half of the adult dose for school-age children). Clinical studies in China have used Ma Zi Ren Wan in children with functional constipation and chemotherapy-induced constipation. For young children, it is often prepared as a porridge (ground seeds cooked with rice) to improve palatability and digestibility. Not recommended for infants without specific practitioner guidance. As with adults, it should be avoided in children with loose stools or weak digestion.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Huo Ma Ren

Laxatives and stool softeners: Concurrent use with pharmaceutical laxatives (e.g. senna, bisacodyl, docusate) may produce additive effects and increase the risk of diarrhea, abdominal cramping, and electrolyte imbalance. Dose adjustment may be needed.

Anticoagulant and antiplatelet drugs: Huo Ma Ren is rich in omega-3 and omega-6 fatty acids. There is a theoretical risk that high doses could have mild blood-thinning effects. Caution is advised with concurrent use of warfarin, heparin, or antiplatelet agents, though clinically significant interactions at standard doses have not been documented.

Antihypertensive medications: Preclinical research has demonstrated that hemp seed protein hydrolysates can lower blood pressure and suppress ACE activity. Patients on antihypertensive drugs should be monitored for additive hypotensive effects, particularly at higher doses.

Sedative/CNS-depressant drugs: Although the properly processed seed kernel contains negligible THC, trace cannabinoid content from incompletely dehulled seeds could theoretically interact with sedatives or CNS depressants. This is primarily a concern with poor quality herb material that retains the outer shell.

Dietary Advice

Foods and dietary considerations when taking Huo Ma Ren

Avoid consuming cold, raw, or greasy foods in excess while using Huo Ma Ren for constipation, as these can impair Spleen function and counteract the herb's benefits. Foods rich in dietary fibre (vegetables, whole grains) complement its bowel-moistening action. Classical sources note that Huo Ma Ren should not be taken together with Mu Li (oyster), Bai Wei, or Fu Ling. Avoid consuming large quantities of tannin-rich foods (strong tea, unripe persimmons) alongside this herb, as tannins may reduce its effectiveness.

Botanical Description

Physical characteristics and morphology of the Huo Ma Ren source plant

Cannabis sativa L. is a fast-growing annual herb of the Moraceae (mulberry) family, reaching 1 to 3 metres in height. The stem is erect and branching, with longitudinal grooves and a covering of fine short hairs. The bark is fibrous and the base becomes somewhat woody. The leaves are palmately compound and alternate on the upper stem (opposite on the lower stem), with 3 to 11 lanceolate leaflets that have serrated margins, deep green and rough on top and densely covered with greyish-white felt-like hairs underneath. Leaf stalks are 4 to 14 cm long.

The plant is dioecious (separate male and female plants). Male flowers are yellowish-green, borne in sparse panicle-like clusters; female flowers are clustered in the leaf axils, each enclosed by an ovate bract. The fruit is a flattened ovoid achene, 4 to 5 mm long, hard-shelled, greyish-brown with fine net-like surface markings, enclosed by yellowish-brown persistent bracts. Flowering and fruiting times vary by latitude: in eastern China, flowers appear May to June and fruits ripen June to July; in northern China, flowering is June to July and fruiting August to September.

Sourcing & Harvesting

Where Huo Ma Ren is sourced, when it's harvested or collected, and how to assess quality

Harvesting season

Autumn, when the fruits are fully mature (typically August to September in northern China, June to July in eastern China).

Primary growing regions

Currently cultivated across China, with major production areas in Heilongjiang, Liaoning, Jilin, Sichuan, Gansu, Yunnan, Guangxi, Shandong, and Hebei provinces. Heilongjiang province is considered the primary daodi (道地) region, with counties such as Hailun, Mingshui, Baiquan, and Qinggang producing large-scale, high-quality hemp seed. Guangxi (especially the Bama longevity region) is also noted for premium quality. The Shanxi province Lingchuan area is known for its 'Ling Wu Wei' (陵五味) brand which includes fire hemp seed as one of five signature local medicinals. Historically, production originated in the Yellow River basin, shifting to the Yangtze River region and northward after the Tang dynasty.

Quality indicators

Good quality Huo Ma Ren seeds are plump, full, and intact, with a yellowish to greyish-green outer surface showing fine net-like markings. They should be uniformly sized (4-5mm long), with no empty or shrivelled seeds. When cracked open, the interior cotyledons should be creamy white and visibly oily. The seed coat should be thin and crisp, breaking easily. The best grade has had the outer husk removed, leaving clean, pale kernels. There should be minimal foreign matter, no insect damage, and no rancid smell. A faint pleasant nutty aroma and bland, slightly sweet taste indicate freshness. Seeds that are dark, mouldy, or have a bitter or off taste should be rejected.

Classical Texts

Key passages from the classical Chinese medical texts that describe Huo Ma Ren and its therapeutic uses

Shen Nong Ben Cao Jing (《神农本草经》)

Original: 麻子，味甘平，主补中益气，肥健不老神仙。

Translation: "Hemp seed, sweet and neutral in flavour. It mainly supplements the Centre and boosts Qi. Long-term use makes one plump, robust, and prevents aging."

Ming Yi Bie Lu (《名医别录》)

Original: 主治中风汗出，逐水，利小便，破积血，复血脉，乳妇产后余疾。

Translation: "Indicated for wind-stroke with sweating, expelling water, promoting urination, breaking accumulated Blood, restoring the blood vessels, and treating lingering illness after childbirth in nursing women."

Yao Pin Hua Yi (《药品化义》)

Original: 麻仁，能润肠，体润能去燥，专利大肠气结便闭。凡老年血液枯燥，产后气血不顺，病后元气未复，或禀弱不能运行者皆治。

Translation: "Hemp seed kernel can moisten the intestines. Its rich, oily nature can dispel dryness, and it is particularly effective at opening Qi stagnation and constipation of the Large Intestine. It treats all cases of dried-up blood and fluids in the elderly, disordered Qi and Blood after childbirth, unrecovered vitality after illness, or constitutional weakness with poor circulation."

Ben Cao Jing Ji Zhu (《本草经集注》) by Tao Hongjing

Original: 畏牡蛎、白薇，恶茯苓。

Translation: "It fears Mu Li (Oyster Shell) and Bai Wei (Cynanchum root), and is averse to Fu Ling (Poria)."

Ben Cao Gang Mu (《本草纲目》) by Li Shizhen

Original: 壳有毒而仁无毒也。

Translation: "The shell is toxic, but the kernel is non-toxic."

Historical Context

The history and evolution of Huo Ma Ren's use in Chinese medicine over the centuries

Huo Ma Ren has one of the longest documented histories of any Chinese medicinal substance, with over 3,000 years of recorded use. The parent plant, hemp (Cannabis sativa), was among the earliest crops cultivated in China, grown for fibre, food, and medicine since the Neolithic period. The Shi Jing (Book of Songs) provides the earliest literary reference to the hemp plant itself. As a medicine, hemp seed first appeared in the Shen Nong Ben Cao Jing under the name "Ma Zi" (麻子), classified as a top-grade (上品) herb suitable for long-term consumption. The Shang Han Lun by Zhang Zhongjing (circa 200 CE) used the name "Ma Zi Ren" (麻子仁) and created the famous formula Ma Zi Ren Wan (Hemp Seed Pill) for treating constipation with Stomach Heat and Spleen weakness, which remains one of the most widely prescribed constipation formulas in China today.

The name "Huo Ma Ren" (火麻仁, literally "fire hemp kernel") first appeared in the Yuan dynasty text Ri Yong Ben Cao (《日用本草》) by Wu Rui. Over the centuries, the herb accumulated numerous aliases including Da Ma Zi, Bai Ma Zi, Dong Ma Zi, and Ma Ren. Li Shizhen's Ben Cao Gang Mu (1596) provided a critical distinction between the non-toxic seed kernel and the potentially psychoactive shell, flowers, and leaves. In the Guangxi Bama region, long famed as a "longevity village," hemp seed has been a dietary staple for generations, and the low incidence of cardiovascular disease and constipation there has been popularly attributed to regular hemp seed consumption.

Modern Research

4 published studies investigating the pharmacological effects or clinical outcomes of Huo Ma Ren

1

Efficacy of a Chinese Herbal Proprietary Medicine (Hemp Seed Pill) for Functional Constipation (RCT, 2011)

Cheng CW, Bian ZX, Zhu LX, Wu JC, Sung JJ. American Journal of Gastroenterology, 2011, 106(1):120-129.

A three-arm randomized controlled trial comparing Ma Zi Ren Wan (Hemp Seed Pill) against senna and placebo in patients with functional constipation. The study found that Hemp Seed Pill was equally effective as senna in increasing complete spontaneous bowel movements during the 8-week treatment period, but showed more sustained benefit during the 8-week follow-up period, with reduced constipation severity and less need for rescue medication.

DOI
2

Herbal Formula MaZiRenWan (Hemp Seed Pill) for Constipation: A Systematic Review with Meta-Analysis (2021)

Yang M, Feng Y, Zhang YL, Smith CM, Hou YN, Wang H, Deng G, Mao JJ. Phytomedicine, 2021, 82:153459.

A systematic review and meta-analysis of 17 randomized trials involving 1,681 constipation patients. Two high-quality trials showed that Hemp Seed Pill significantly increased weekly complete spontaneous bowel movements compared to placebo. The review concluded that HSP was effective for functional constipation in Asian populations with a favourable safety profile and did not increase adverse events compared to controls.

DOI
3

Chinese Herbal Medicine (MaZiRenWan) Improves Bowel Movement in Functional Constipation Through Down-Regulating Oleamide (Mechanistic RCT substudy, 2019)

Huang T, Zhao L, Lin CY, Lu L, Ning ZW, Hu DD, Zhong LLD, Yang ZJ, Bian ZX. Frontiers in Pharmacology, 2019, 10:1570.

A pharmacometabolomic analysis using serum samples from 85 functional constipation patients in a prospective three-arm RCT. The study found that Ma Zi Ren Wan improved bowel movements through a mechanism involving downregulation of oleamide, a fatty acid amide that regulates intestinal motility, likely by enhancing fatty acid amide hydrolase-mediated degradation.

DOI
4

Preventive and Treatment Effects of a Hemp Seed Meal Protein Hydrolysate Against High Blood Pressure in Spontaneously Hypertensive Rats (Preclinical, 2014)

Girgih AT, Alashi A, He R, Malomo S, Aluko RE. European Journal of Nutrition, 2014, 53(5):1237-1246.

An animal study investigating hemp seed meal protein hydrolysate (HMH) in spontaneously hypertensive rats. Feeding HMH-containing diets for 4 weeks led to significant reductions in systolic blood pressure (from ~145 to ~119 mmHg vs 150 mmHg in controls), along with suppressed plasma ACE activity and decreased renin levels, suggesting potential as a therapeutic agent for hypertension prevention and treatment.

DOI

Research on individual TCM herbs is growing but still limited by Western clinical trial standards. These studies provide emerging evidence and should be considered alongside practitioner expertise.