Educational information, not medical advice — ask your doctor or midwife.
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Su Mu is the dried red heartwood of the sappan tree (Caesalpinia sappan). In Chinese medicine it is used mainly for bruises, swelling and pain after an injury. It is a single herb, not a mixed product.
It is also used for period pain and for pain after childbirth. Chinese practice describes these as problems of "blood stasis", meaning blood that is not moving freely. Su Mu is almost always one part of a larger formula, not a stand-alone cure.
Here is the evidence verdict up front. Su Mu has a long record in Chinese medicine, but human trial evidence is very thin. Nearly all research is laboratory and animal work.
Long traditional use tells you that people valued a herb. It does not tell you that the herb works. Those are two separate things, and we report both.
Honestly, how Su Mu acts in the body is not settled.
The traditional idea is simple. Su Mu is said to move stagnant blood, break up clots and ease the pain and swelling that follow a blow.
Modern work is mostly in cells and animals. In test-tube studies, brazilin from Su Mu appears to slow platelet clumping, the first step in forming a clot. In animal studies, extracts appear to reduce swelling and markers of inflammation.
Laboratory tests also show it slowing the growth of some bacteria. Whether any of this happens at the doses people take is not known.
Because of the platelet findings, we treat a possible blood-thinning effect as real enough to plan around. That is a safety judgement, not a proven benefit.
Su Mu is sold mainly as chips, shavings or coarse powder of the red heartwood.
Common forms include: - Raw chips or shavings for a decoction (a water-based brew) - Granules made from a concentrated extract - Powder inside multi-herb pills or capsules - Liquid extracts and tinctures
It is also used outside medicine as a red dye for cloth and food. Dye-grade wood is not intended for swallowing.
Su Mu has been used in China for well over a thousand years. It appears in Tang dynasty writings and in later herbals such as the Ben Cao Gang Mu.
The wood came into China through trade with Southeast Asia. It is used in Vietnamese, Indian and Indonesian practice too, often as both medicine and dye.
Its classic place is in trauma medicine. Bone-setters and martial arts healers used it for bruising and swelling.
See a doctor straight away if you bruise for no reason, bleed longer than usual from a small cut, or see blood in your urine, stools or vomit.
Get urgent help for a severe headache, sudden weakness, or black tarry stools. These can be signs of bleeding inside the body.
Stop the herb and seek care if you get a rash, swelling of the lips or face, or trouble breathing.
See your doctor rather than self-treating if pain after an injury is severe, if a limb looks deformed, or if swelling keeps growing. Also get checked if your periods stop and you do not know why.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Su Mu is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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