Educational information, not medical advice — ask your doctor or midwife.
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Shigyakusan is a four-herb Japanese Kampo formula used for tension that shows up in the gut and the ribs. Practitioners reach for it when stress brings on a tight, full feeling under the ribs, cramping belly pain, or bowel habits that swing between loose and blocked. The Japanese romanised name is Shigyakusan; the same formula is known as Sini San in Chinese practice.
It is one of the 148 Kampo formulas approved by Japan's Ministry of Health, Labour and Welfare (MHLW) for national health insurance cover. That means a doctor in Japan can prescribe a standard extract granule, and the product is made to a set recipe. Approval covers manufacturing and reimbursement; it is not the same as proof from modern trials.
Honest verdict up front: the evidence here is traditional, not clinical. Long use in Kampo and Chinese medicine tells us how practitioners have used it, but it does not prove the formula works. We could not find published randomised human trials of Shigyakusan for any condition.
Nobody has shown how Shigyakusan works in people. The explanations below are either traditional ideas or laboratory findings, and neither one proves an effect in your body.
In Kampo terms, the formula is said to free "stuck" energy in the middle of the body and ease the tight feeling under the ribs. Bupleurum and immature bitter orange are the moving herbs; peony and licorice are the softening, cramp-easing pair.
In the lab, peony and licorice relax smooth muscle (the muscle in your gut wall), and bupleurum compounds act on inflammation signals. These are test-tube and animal results. They are a hint, not a mechanism.
You will most often meet Shigyakusan as a dried extract granule or fine powder in a foil sachet. This is the standard Japanese prescription and over-the-counter form.
Other forms include: - Extract tablets or capsules, for people who dislike the taste - A traditional powder of the raw herbs, mixed into warm water - A decoction (a tea simmered from the cut herbs), less common today
Strength differs between makers. A 7.5 g daily dose of one brand's granules is not the same as 7.5 g of another's, so follow the label on the box you actually hold.
Shigyakusan comes from the Shanghan Lun (Treatise on Cold Damage), a Chinese medical text compiled around 200 CE. It has been copied into and used by almost every East Asian herbal tradition since.
Japanese Kampo doctors adopted it centuries ago and narrowed its use, matching it to a specific body sign: tightness and discomfort under the lower ribs on both sides. Modern Japan lists it among the 148 insurance-covered Kampo formulas.
Stop taking it and see a doctor the same day if you notice swelling in your face, hands or ankles, fast weight gain, headaches, muscle weakness or cramps, or a heartbeat that feels odd. These can be signs that your potassium (a blood salt) has fallen too low.
Get medical help urgently if your skin or the whites of your eyes turn yellow, your urine goes dark, or you feel deeply tired and sick. Those can be signs of liver injury.
Go to hospital if you develop a dry cough, fever and breathlessness that come on over days. That can be a rare lung inflammation linked to bupleurum.
Also see a doctor before starting if your belly pain is severe, one-sided, or comes with fever, vomiting or blood in the stool. Those need a diagnosis first.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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