Educational information, not medical advice — ask your doctor or midwife.
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Sha Yuan Zi is the dried seed of a small pea-family plant, Astragalus complanatus. In English it is called flatstem milkvetch seed. It is one single herb used in Traditional Chinese Medicine (TCM), not a blend.
TCM herbalists use it as a mild tonic for what they call the kidney system. The usual traditional aims are to cut down on night-time urination, to ease a sore low back, and to help blurry eyes.
Here is the short verdict. The herb has a long, steady place in one tradition, but we could find no human trials of it on its own. Long use is not proof that a herb works, and that holds for every claim on this page.
No one has shown how Sha Yuan Zi works in the human body. What follows is theory, not proven fact.
In TCM terms, the seed is said to be sweet, warm and astringent. Astringent means it is thought to hold things in, such as urine or semen. TCM texts also link it to the liver system and to clear sight.
In the lab, extracts of the seed contain flavonoids. These are plant pigments that can mop up harmful molecules in a test tube. Some animal studies suggest effects on blood sugar and on eye tissue, but animal results often fail to repeat in people.
The most common form is the whole dried seed, simmered in water to make a decoction (a strong herbal tea). A second form is the salt-fried seed. Frying with brine is a classic step said to steer the herb toward the kidney system.
You may also see powders, granules and capsules. These are often made from a water extract of the seed.
Sha Yuan Zi is rarely taken alone. It usually sits inside a multi-herb formula chosen by a trained practitioner.
Chinese doctors have used this seed for many centuries. It appears in materia medica works of the Tang and Song eras and is well settled by the Ming and Qing periods. It is a named ingredient in old kidney-tonic formulas such as Jin Suo Gu Jing Wan.
It remains on modern Chinese pharmacopoeia lists today. Its standing rests on tradition and long use, not on trial data.
See a doctor if your symptoms do not improve after four to six weeks, or if they get worse at any time.
Get medical help the same day if you have burning when you pass urine, blood in your urine, a fever, or pain in your side or lower belly.
Get urgent help if you have a rash with swelling of the lips, tongue or throat, or trouble breathing. Also seek urgent care for sudden loss or blurring of vision, or for back pain with numb or weak legs or loss of bladder control.
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 Sha Yuan Zi 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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