Huo Ma Ren
StarCannabis sativa L.
Traditionally used for
- Bowel health
- Urinary & fluids
- Menstrual & women's health
- Sleep
- Pain & joints
☯ TCM Properties
Moistens the Intestines and Unblocks the Bowels; Nourishes Yin; Promotes Urination; Invigorates Blood and Dispels Stasis
Traditional Chinese Uses
Huo Ma Ren (hemp seed) is a neutral, sweet, oily herb used in Chinese medicine to moisten the Intestines and gently relieve constipation from dryness — particularly in the elderly, postpartum women, and those constitutionally dry or Blood deficient. Its moist, lubricating quality softens dry stools and promotes gentle bowel movement without harsh cathartic side effects. As a food-grade herb and nutritious seed, it is among the safest and gentlest laxative herbs in the Chinese materia medica.
Western Herbalism Properties
Traditional Uses
The Iroquois used Cannabis sativa as a psychological aid, given after a patient had recovered but did not think themselves recovered, and as a stimulant, stating that "this plant will get you going" (Herrick, 1977, Iroquois Medical Botany, State University of New York, Albany, page 306).
Pharmacological Effects
- Purgative: Mild purgative acting by stimulating intestinal mucosa, increasing secretion and peristalsis.
- Hypotensive: Oral hemp seed lowered blood pressure in animals and humans; an emulsion for 4 weeks lowered BP from 140/100 to 120/80 mmHg, maintained at 115/80 mmHg with 5-6 weeks' continued use.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 238.
Used In Formulas (13)
Relationships
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Botanical Description
Cannabis sativa is a fast-growing annual herb in the Cannabaceae, probably native to central Asia and now cultivated worldwide for fibre, oilseed and medicinal preparations. The plant produces an erect, often single, ridged and hairy stem 1 to 4 meters tall, with palmately compound leaves arranged oppositely below and alternately above. Each leaf has 3 to 11 lanceolate, sharply serrate leaflets joined at a single point on a long petiole, with a deep green, slightly rough upper surface and a paler underside studded with resinous glandular trichomes, especially on female inflorescences. The species is typically dioecious. Male plants bear loose, branching panicles of small, five-parted, pendulous greenish-yellow flowers shedding wind-borne pollen; female plants produce dense leafy spikes of single-flowered axillary clusters with a tubular perianth enclosing the ovary. The fruit is a small, smooth, somewhat lens-shaped achene (the hemp seed) 3 to 5 mm long, greyish-brown and often mottled, containing a single oily seed. The dried ripe seed constitutes the Chinese drug Huo Ma Ren.
Active Constituents
Fixed seed oil (triacylglycerols)
Fixed oilConcentration: roughly 25-35% of the seed; mean 31.7% of dry matter across 29 industrial hemp varieties
The bulk of the seed by weight and the basis of its classical action of moistening the Intestines: an unabsorbed oily residue plus the crushed seed coat softens stool and lubricates transit rather than stimulating the colon. This is a bulk-and-lubricant mechanism, not an anthranoid one, which is why Huo Ma Ren is used in frail, elderly and postpartum patients in whom Da Huang or senna would be too harsh.
Linoleic acid
Polyunsaturated fatty acid (omega-6)Concentration: about 55% of total seed fatty acids (mean 55.5% across 29 industrial varieties)
The dominant fatty acid of hemp seed oil. Nutritionally an essential fatty acid; it contributes to the emollient, stool-softening character of the drug rather than to any specific pharmacological laxative effect.
alpha-Linolenic acid
Polyunsaturated fatty acid (omega-3)Concentration: about 16% of total seed fatty acids (mean 16.05% across 29 industrial varieties)
Gives hemp seed an unusually low omega-6 to omega-3 ratio for a seed oil, roughly 3:1. It is also the reason the crushed seed oxidises quickly: rancid Huo Ma Ren is a real quality problem and stale stock should be rejected.
gamma-Linolenic acid
Polyunsaturated fatty acid (omega-6)Concentration: about 2% of total seed fatty acids (mean 1.98% across 29 industrial varieties)
An uncommon fatty acid in food seeds, present in hemp seed at a small but consistent level. It is a precursor of dihomo-gamma-linolenic acid and thence of series-1 prostaglandins.
Edestin
11S seed storage globulin (protein)Concentration: the principal protein fraction; total crude protein averages about 25% of seed dry matter
The main storage protein of hemp seed and the reason the drug is also a food. It is not laxative, but it makes the whole seed a substantial nutritional load, which matters when Huo Ma Ren is prescribed at the usual 10-15 g and is being eaten daily for weeks.
Cannabisins A-F and related lignanamides
Phenolic amide (lignanamide)Concentration: concentrated in the hull rather than the kernel; absolute levels vary widely with cultivar and dehulling
The characteristic phenolics of hemp seed, built from N-trans-caffeoyltyramine units. They carry antioxidant and acetylcholinesterase-inhibitory activity in vitro and are largely removed when the seed is dehulled, so hulled and unhulled Huo Ma Ren are chemically different drugs.
N-trans-Caffeoyltyramine
Hydroxycinnamic acid amideConcentration: a hull phenolic; reported alongside the cannabisins in hempseed hull fractions
The monomeric building block of the seed lignanamides and itself an antioxidant phenolic amide of the hull.
delta-9-Tetrahydrocannabinol
CannabinoidConcentration: not synthesised by the seed; present only as surface contamination. Mean 7.83 µg/g across 29 industrial hemp varieties, detectable in only 5 of the 29; commercial hemp seed oils carried 0.2-6.7 mg/kg in a 2024 survey of 30 oils
The seed testa bears no glandular trichomes, so hemp seed itself makes essentially no THC. What is measured comes from resin transferred from flowers and leaves during harvest and pressing, and it sits on the outside of the seed. At these levels the drug is not psychoactive at any plausible clinical dose, but the contamination is analytically real and is the entire basis of the drug-screen problem recorded under interactions. The EU sets maximum levels of 3.0 mg/kg for hemp seeds and 7.5 mg/kg for hemp seed oil.
Cannabidiol
CannabinoidConcentration: mean 39.54 µg/g across 29 industrial hemp seed varieties, again as surface contamination rather than a seed metabolite
Present for the same reason as THC and at similarly trace levels. It is pharmacologically irrelevant at the amounts a decoction of Huo Ma Ren delivers, but its presence is one of the reasons hemp seed products are caught by cannabis-specific import and food rules in some jurisdictions.
⚠ Drug Interactions
Workplace and clinical urine cannabinoid immunoassays (THC-COOH screens)
Hemp seed carries resin-derived delta-9-THC on the seed coat. In a controlled human ingestion study a volunteer taking cold-pressed hemp seed oil twice daily for 4.5 days (135 mL total) produced urine 11-nor-delta-9-THC-carboxylic acid of 41-68 ng/mL, crossing the standard 50 ng/mL immunoassay cut-off, and did not test negative until 146 hours after starting, some 53 hours after the last dose. A 2024 survey of 30 commercial hemp seed oils found 0.2-6.7 mg/kg delta-9-THC with three samples above the EU limit for oils, so contamination is not hypothetical or historical. The magnitude depends entirely on how the batch was harvested and cleaned; dehulled seed carries less.
Clinical note: Ask before prescribing whether the patient is subject to drug testing of any kind. If they are, either avoid Huo Ma Ren or document the prescription in advance with dates and product batch, and tell the patient to disclose it to the testing body. A positive screen is confirmed by GC-MS for the same metabolite, so confirmatory testing will not exonerate them; only prior documentation will. Bai Zi Ren, Yu Li Ren or Song Zi Ren are reasonable moistening substitutes.
Cannabis and cannabinoid legal controls (national narcotics and food law)
Huo Ma Ren is the ripe seed of Cannabis sativa L. and is a bulk laxative essentially free of THC, but many statutes are written against the species rather than the plant part or the cannabinoid content. Positions differ sharply: hemp seed is an accepted food in the EU and the UK and is subject only to contaminant limits (3.0 mg/kg delta-9-THC in seeds, 7.5 mg/kg in seed oil under Commission Regulation (EU) 2022/1393); hulled hemp seed is GRAS in the United States and hemp was descheduled federally in 2018; Australia permits hemp seed as food but regulates importation under the Customs (Prohibited Imports) Regulations; Japan permits hemp seed under the Cannabis Control Act but applies a zero-tolerance reading of THC presence, so a detectable residue is treated as evidence that controlled plant parts were used. Viable (non-sterilised) seed is separately restricted in several jurisdictions because it can be germinated.
Clinical note: Check the position where you actually practise and where the herb will be shipped from and to, before dispensing rather than after. Buy from a supplier who can produce a THC certificate of analysis for the batch and who supplies sterilised, non-viable seed. Do not assume that because the seed is legal as a food it is legal to import as a medicine, or vice versa.
Stimulant and osmotic laxatives (senna, bisacodyl, macrogol, lactulose)
Huo Ma Ren works by softening and bulking stool, a mechanism independent of the anthranoid or osmotic action of conventional laxatives, so the effects add rather than overlap. Ma Zi Ren Wan, the formula in which Huo Ma Ren is chief, already contains Da Huang, and in the 291-patient trial that compared the formula with senna the two were of broadly similar efficacy, which indicates the herbal regimen is doing comparable work to a stimulant laxative and does not need one stacked on top.
Clinical note: Taper the conventional laxative rather than running both at full dose. Watch for the common clinical picture of a patient who continues over-the-counter senna while starting a herbal formula and then presents with cramping diarrhoea.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 10–15 g | Daily | — | — | 中国药典 2020 【用法与用量】10～15g。 【性味与归经】甘，平。归脾、胃、大肠经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Moistening the intestines combined with gentle purging of heat, which moves dry stool while limiting injury to fluids.
Heat-dryness constipation with frequent urination (spleen-binding pattern), taken as pills for a mild action.
Core pair of a classical formula — Ma Zi Ren Wan, Shang Han Lun (Zhang Zhongjing)
Oily moistening of the intestines combined with descending of Lung qi, which helps move the bowels because the Lung and Large Intestine are paired.
Dry constipation with intestinal dryness (spleen-binding pattern).
Core pair of a classical formula — Ma Zi Ren Wan, Shang Han Lun (Zhang Zhongjing)
Evidence Tier
Strong evidence · 4 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
1
1 verified · 0 unverified
Randomized controlled trial
2
2 verified · 0 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
1
0 verified · 1 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Efficacy of a Chinese Herbal Proprietary Medicine (Hemp Seed Pill) for Functional Constipation
Two-part study in Hong Kong. A dose-finding arm in 96 subjects selected 7.5 g twice daily of Hemp Seed Pill (Ma Zi Ren Wan) over 2.5 g and 5.0 g. In the double-blind placebo-controlled arm, 120 patients with Rome III functional constipation of excess pattern were randomised 1:1 for eight weeks. Responder rates for complete spontaneous bowel movements were 43.3% on the formula versus 8.3% on placebo during treatment, and 30.0% versus 15.0% during the eight-week follow-up. No serious adverse events. Note that the intervention is the six-herb formula, in which Cannabis sativa seed is the chief herb but is given alongside Da Huang, Bai Shao, Ku Xing Ren, Zhi Shi and Hou Po; the trial does not isolate the effect of Huo Ma Ren.
Efficacy of MaZiRenWan, a Chinese Herbal Medicine, in Patients With Functional Constipation in a Randomized Controlled Trial
Double-blind, double-dummy, three-arm trial in 291 Rome III functional constipation patients across eight Hong Kong clinics, comparing Ma Zi Ren Wan 7.5 g twice daily, senna 15 mg daily and placebo over eight weeks with eight weeks of follow-up. Complete response at week 8 was 68% for the formula, 57.7% for senna and 33.0% for placebo; the formula beat placebo (P less than .005) but not senna (P = .14). At week 16, after treatment had stopped, 47.4% of the formula group were still complete responders versus 20.6% on senna and 17.5% on placebo. Colonic transit improved on the formula. Again the unit of treatment is the whole formula, not Huo Ma Ren alone.
Herbal formula MaZiRenWan (Hemp Seed Pill) for constipation: A systematic review with meta-analysis
Seventeen randomised trials with 1681 constipation patients, all conducted in east Asia and all at moderate to high risk of bias. Two high-quality trials showed the formula increased weekly complete spontaneous bowel movements by a mean difference of 0.95 (95% CI 0.56 to 1.35) versus placebo, with a complete response risk ratio of 1.43 (95% CI 1.20 to 1.71) in functional constipation. Adverse events were not increased. The authors are explicit that generalisability outside east Asian populations is unproven.
Cannabis sativa L. alleviates loperamide-induced constipation by modulating the composition of gut microbiota in mice
One of the few studies to test the single herb rather than the formula. A water extract of the Cannabis sativa seed drug improved intestinal motility and water-electrolyte handling, reduced inflammatory markers and preserved the gut barrier in loperamide-constipated mice, and remodelled the microbiota with changes in Butyricicoccus and Parasutterella. When the intestinal flora was depleted with antibiotics the laxative effect was abolished, which argues the action is at least partly microbiota-dependent rather than purely mechanical. Mouse data only; no human confirmation.
⚠ Safety & Contraindications
Contraindications
Its use is cautious in patients with thin, unformed stool, yang wěi (impotence), seminal emission, and abnormal vaginal discharge.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 94.
Side Effects
- No hallucinogenic effect of the seed is mentioned in classical Chinese literature
- Large doses caused cholinergic intoxication (nausea, vomiting, diarrhea, convulsion, coma) attributed to muscarine
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 238.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyShang Han Lun
Han dynastyBen Cao Gang Mu
Ming dynastyReferences
- Arango S, Kojic J, Perovic L, Dermanovic B, Stojanov N, Sikora V, Tomicic Z, Raffrenato E, Bailoni L. Chemical Characterization of 29 Industrial Hempseed (Cannabis sativa L.) Varieties . Foods (2024) [DOI]
- Struempler RE, Nelson G, Urry FM. A Positive Cannabinoids Workplace Drug Test Following the Ingestion of Commercially Available Hemp Seed Oil . Journal of Analytical Toxicology (1997) [DOI]
- Lindekamp N, Triesch N, Rohn S, Weigel S. Quantification of sixteen cannabinoids in hemp seed edible oils and the influence of thermal processing on cannabinoid contents and profiles . Food Additives & Contaminants: Part A (2024) [DOI]
- Yan X, Tang J, dos Santos Passos C, Nurisso A, Simoes-Pires CA, Ji M, Lou H, Fan P. Characterization of Lignanamides from Hemp (Cannabis sativa L.) Seed and Their Antioxidant and Acetylcholinesterase Inhibitory Activities . Journal of Agricultural and Food Chemistry (2015) [DOI]
- Leonard W, Zhang P, Ying D, Xiong Y, Fang Z. Extrusion improves the phenolic profile and biological activities of hempseed (Cannabis sativa L.) hull . Food Chemistry (2021) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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