Educational information, not medical advice — ask your doctor or midwife.
Onkeito is a Japanese Kampo herbal formula for menstrual problems. Its name means "warming the menses decoction". It is a fixed blend of about twelve herbs, taken as a drink or granule.
Kampo doctors give it for irregular periods, period pain and light, dragging bleeding. It is also used for cold hands and feet, dry lips and hot palms. In Japan it is a ministry-approved Kampo formula, sold as Tsumura 106.
The honest evidence picture is simple. The traditional record is long and clear, but good human trial data is thin. Long use in a tradition is not proof that a remedy works.
No one has shown how Onkeito works in the body. That is the plain answer.
Kampo theory says the blend warms the womb and moves "blood stasis", a traditional idea of stuck or cold blood. This is a way of choosing the formula for a patient. It is not a lab finding.
Some single herbs in the blend have been studied in cells and animals. In that work they appear to affect blood flow, hormone signals and smooth muscle. Whether any of this happens in women who take the finished formula is not established.
Most people take Onkeito as a granule powder that dissolves in hot water. In Japan this is the ministry-approved product Tsumura 106.
It also comes as a classic decoction. The dried herbs are boiled in water and the liquid is drunk warm. Tablets and capsules exist but are less common.
Buy only from a licensed maker or a trained practitioner. Hange must be correctly processed, and home-made mixes can get that step wrong.
Onkeito comes from the Jin Gui Yao Lue, a Chinese medical text from around 200 CE. There it is called Wen Jing Tang.
Japanese Kampo doctors took it up and have used it for centuries. Japan's health ministry later approved it as a standard prescription Kampo formula, Tsumura 106.
It is still used in Chinese and Korean herbal practice under its older name. That gives it a classical standing across more than one tradition.
Stop taking it and see a doctor the same day if your face, hands or ankles swell, if you gain weight fast, or if your blood pressure climbs.
Get urgent medical help if your skin or eyes turn yellow, your urine goes dark, or you feel very tired and sick. These can be signs of liver injury.
Also seek urgent help for muscle weakness, strong cramps, or a heart that races or flutters. A new dry cough with fever or breathlessness needs same-day care too.
See your doctor first, before you start, if you bleed between periods, bleed after sex, or your periods suddenly change. Those signs need a proper check.
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 Onkeito 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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