Shigyakusan
Quick Facts
- What it is: Shigyakusan is a four-herb Kampo formula, on Japan's list of 148 insurance-approved formulas, traditionally used for stress-linked gut pain and tightness under the ribs.
- Main uses: Stress-linked gut symptoms, Tightness under the ribs, Cramping belly pain
- Best for: People matched to the Kampo pattern of rib tightness with tension, Short review-and-reassess courses under a practitioner
- Active ingredients: Saikosaponins from bupleurum root (saiko), Paeoniflorin from peony root (shakuyaku), Synephrine from immature bitter orange peel (kijitsu), Glycyrrhizin from licorice root (kanzo)
- Forms: Extract granules in sachets, Extract tablets or capsules, Traditional powder, Decoction (simmered tea)
- Time to effect: Days to two weeks in people who respond; reassess at four weeks if nothing changes.
- Side effects: Usually mild stomach upset; rarely swelling, high blood pressure, low potassium, liver injury or lung inflammation.
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What is Shigyakusan?
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.
How does Shigyakusan work?
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.
What forms does Shigyakusan come in?
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.
Where it comes from:
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.
Who should avoid Shigyakusan?
- Do not use if you have low potassium (a low level of an important blood salt), because the licorice in this formula can push it lower.
- Do not use if you have aldosteronism, a hormone disorder that makes the body hold on to salt.
- Do not use if you have myopathy (a muscle disease causing weakness) or the inherited muscle disorder called thyrotoxic periodic paralysis.
- Do not use if you are taking interferon injections for hepatitis, because bupleurum with interferon has been linked to serious lung injury.
- Do not use if you are taking digoxin (a heart medicine) unless your heart doctor has approved it.
- Do not use if you have heart failure, poorly controlled high blood pressure, or serious kidney disease, unless a doctor is supervising you.
- Do not use if you are pregnant or breastfeeding, unless a Kampo-trained doctor prescribes and monitors it.
- Do not use if you have ongoing liver disease or unexplained liver blood test results.
- Avoid taking it alongside another Kampo formula that contains licorice (kanzo) without asking a pharmacist to add up the total.
- Do not give it to a child without a practitioner's dose and supervision.
When should you see a doctor?
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.
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