A "run-chang tong-bian" (moisten the intestines and unblock the bowels) formula from Zhang Zhongjing's "Treatise on Cold Damage" (c. 200 CE), the canonical TCM "constipation from dryness" formula.
Cultural reference - how this formula has been discussed in Chinese medical tradition. Not medical advice.
Background & origin
Compiled by Zhang Zhongjing in the "Treatise on Cold Damage" (《伤寒论》) around 200 CE as the canonical "spleen-constraint with intestinal dryness" formula, it has been continuously in use for nearly two thousand years. In Japan, it is sold as 麻子仁丸 (マシニンガン / Mashinin-gan) by Tsumura (ツムラ) and is one of the most commonly prescribed kampo formulas for chronic constipation in older or frailer patients. In Korea, similar "마자인환" preparations are produced in the broader hanbang digestive line, often by smaller specialty makers. The formula is, in short, one of the most enduring TCM laxative prescriptions in East Asia.
From the source text
This page is cultural documentation, not medical advice.
From the source text · 卷五·辨阳明病脉证并治·第 247 条
Classical text
趺阳脉浮而涩，浮则胃气强，涩则小便数，浮涩相搏，大便则硬，其脾为约，麻子仁丸主之。
Modern Chinese rendering
足背趺阳脉浮而涩：浮主胃气偏盛，涩主小便频数；浮涩相搏则大便干结难下，这是脾被胃约束、不能为胃行其津液的"脾约"证，用麻子仁丸主治。这是"脾约便秘"思路的代表性条文。
Editorial translation
The pulse at the fuyang position on the dorsum of the foot is floating and choppy, floating means the stomach qi is in excess, choppy means the urine is frequent, when the floating and the choppy combine then the stool is hard, the spleen is "constrained" by the stomach, and Hemp Seed Pills is the formula of choice. This is the canonical clause for the "spleen-constraint constipation" line of reasoning, in which the spleen can no longer transport fluids on behalf of the stomach and the intestines are left dry.
In tradition
In TCM framing, traditionally used in the context of "spleen-constraint" with intestinal dryness, hard, dry stools, difficulty in passing, occasional abdominal fullness, and a tendency for constipation to recur in older or weaker patients. It is one of the most widely sold "moistening laxative" formulas in Chinese pharmacies and is one of the gentler classical formulas for chronic constipation. In Japan, it is sold as 麻子仁丸 (Mashinin-gan) by Tsumura (ツムラ) and is one of the most commonly prescribed kampo formulas for chronic constipation in older patients.
Formula composition
Monarch1
- Hemp seed (Má Zǐ Rén / 麻子仁 / Huǒ Má Rén / 火麻仁) - principal herb, moistens the intestines
Other ingredients6
- White peony root (Bái Sháo / 白芍) - nourishes blood, softens the liver
- Immature bitter orange (Zhǐ Shí / 枳实) - moves qi, breaks stagnation
- Rhubarb root (Dà Huáng / 大黄) - purges accumulation
- Magnolia bark (Hòu Pò / 厚朴) - moves qi, dries dampness
- Apricot kernel (Xìng Rén / 杏仁) - descends lung qi, helps the bowels
- Honey (Fēng Mì / 蜂蜜) - moistens, carries the formula
International availability
Cautions & context
- Not appropriate for acute abdominal pain with fever or suspected obstruction, the formula is for chronic "dryness-type" constipation, not for acute abdominal emergencies.
- Pregnant women should not use without qualified guidance, the formula contains rhubarb (Dà Huáng) and is considered a "purging" prescription in TCM pregnancy guidance.
- Long-term daily use is generally discouraged, the formula is intended for short-term use during a defined constipation episode.
- Persistent change in bowel habits lasting more than two weeks, especially with weight loss or blood in stool, should be evaluated by a clinician, TCM self-care is not a substitute for evaluation of serious bowel conditions.
Related formulas
Other formulas from this text· "Treatise on Cold Damage"
Other formulas by this contributor· Zhang Zhongjing
Related concerns
Concern · digestion
Digestion
Upper-abdominal heaviness, bloating, sour reflux, loose stools, traveler's stomach, and the aftermath of a meal that was richer, spicier, or larger than usual.
Editorial note
Compiled from "Treatise on Cold Damage" (200).
Last reviewed: July 18, 2026
Three layers of evidence
Classical source
≈ 1800 years · "Treatise on Cold Damage" (200)
Pharmacopoeia indication
"Moisten the intestines and unblock the bowels. Used for constipation due to intestinal heat and fluid depletion: dry stool difficult to pass, and abdominal fullness and discomfort."
Modern research status
As of 2026-07-18, a PubMed search using the formula name and the Latin / Korean / Japanese transliterations together with "systematic review" and "meta-analysis" did not identify a dedicated systematic review for this formula. Any clinical evidence that does exist is fragmented across small individual trials or covered in broad herbal-medicine umbrella reviews, which do not allow a per-formula evidence assessment; the absence of a dedicated SR is itself the relevant editorial fact here.
References
References reviewed on July 18, 2026 · PubMed search on 2026-07-18
- 01ClassicalZhang Zhongjing, 《伤寒论》 (Shānghán Lùn / Treatise on Cold Damage), Eastern Han dynasty, c. 200 CE, with the base formula appearing in clause 247 of the "yangming" section, the canonical text for "spleen-constraint" (脾约) constipation.
- 02TextbookDuan Fuqin (段富津) et al. (eds.), 《方剂学》 (Fāngjìxué / Textbook of Formulas), Shanghai Scientific and Technical Publishers, 1995, the standard modern university-level formula textbook in mainland China, with Ma Zi Ren Wan analysed as the representative "moisten the intestines and unblock the bowels" formula.
- 03PharmacopoeiaChinese Pharmacopoeia Commission, 《中华人民共和国药典》 2020 年版一部 (Zhōnghuá Rénmín Gònghéguó Yàodiǎn, Pharmacopoeia of the People's Republic of China, 2020 Edition, Vol. I), China Medical Science Press, 2020, the official monograph for Ma Ren Wan / Ma Zi Ren Wan dosage forms.