Educational information, not medical advice — ask your doctor or midwife.
Koshaheiisan is a Japanese Kampo herbal formula for a heavy, bloated, sluggish stomach. It is used for fullness after meals, poor appetite, nausea and loose stools. Japan's health ministry approves it as a Kampo medicine, and Tsumura is one of the makers.
It is the classic Heiisan base with two extra herbs. The base is Atractylodes lancea root, magnolia bark, citrus peel, licorice root, ginger and jujube. To that it adds cyperus root and amomum fruit.
Here is the honest verdict. The formula has long standing in Kampo practice, but we could not find human trials of it. Long use in a tradition is not the same as proof of effect.
One safety point shapes the whole page. The licorice in it can raise blood pressure and drop your potassium. That is covered in full below.
No one has shown in people how this formula works. What follows is theory plus laboratory work.
Kampo theory describes it as warming and drying a "damp", heavy stomach. Cyperus and amomum are said to get a stalled stomach moving again. That is a traditional idea, not a measured effect.
Some single herbs have been studied in the lab. In animal and cell work, ginger and citrus peel appear to speed stomach emptying. Magnolia bark compounds relax gut muscle in test-tube studies.
One mechanism is well established in people, and it is a risk, not a benefit. Glycyrrhizin from licorice blocks an enzyme called 11-beta-HSD2, which normally shields the kidney's salt switch. The result can be pseudoaldosteronism (a salt and potassium imbalance): the body holds salt and water, loses potassium, and blood pressure rises.
Most people in Japan take a dried extract granule, sold in single-dose sachets.
Other forms exist. Some makers press the same extract into tablets or fill capsules. Traditional practitioners may also cook the raw herbs into a tea (a decoction).
Granules are the form used in Japanese hospital and pharmacy practice, and the form most dosing advice refers to.
Heiisan is an old Chinese formula, written down in the Song dynasty Taiping Huimin Heji Jufang, around 1100 CE. Adding cyperus and amomum gives Koshaheiisan, known in Chinese as Xiang sha ping wei san.
Japanese Kampo doctors adopted it and have used it for centuries for weak, damp digestion. Japan now lists it among its approved Kampo medicines, which is a regulatory listing, not a finding of proven benefit.
Some reactions to Koshaheiisan need urgent care. Call your local emergency number or go to an emergency department straight away — do not wait to see whether it passes.
Stop the formula and call your doctor if your ankles, hands or face swell, if you gain weight fast, or if your muscles feel weak, sore or crampy. These can be signs that your potassium has dropped.
Also call if your blood pressure climbs, you get bad headaches, your skin or eyes turn yellow, or your urine goes dark.
Get emergency help for an irregular or racing heartbeat, fainting, chest pain, or severe muscle weakness that you cannot walk on.
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 Koshaheiisan 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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