Educational information, not medical advice — ask your doctor or midwife.
Ryutanshakanto is a Kampo herbal formula from Japan. It is used for burning or painful urination, cloudy urine, vaginal discharge, and itching in the groin. The Japanese romanised name is Ryutanshakanto.
It is one of the 148 Kampo formulas approved by the MHLW (Japan's Ministry of Health, Labour and Welfare) for cover under national health insurance. Doctors and pharmacists there prescribe it often.
The honest verdict on evidence: tradition is strong, proof is weak. We could not find a good human trial of this formula. Long use in Japan is not proof that it works, and this is the only time we will say so.
It also carries real drug risks, mostly from the licorice root in it. Read the safety notes below before you take it.
No one has shown how it works in the body. The honest answer is that we do not know.
In Kampo thinking, it clears "damp heat" from the liver channel and the lower body. That is a traditional idea, not a lab finding.
Lab and animal work gives a few hints. Chemicals from skullcap root and gardenia fruit calm inflammation (swelling and irritation in tissue) in test tubes. Plantain seed and water plantain may make you pass more urine.
None of that has been shown to explain what a person feels. Treat any mechanism talk as a guess.
Most people take dried extract granules from a sachet. Tablets and capsules are also sold.
A few practitioners still boil the raw herbs into a tea, called a decoction. Products differ by maker, so check the label for the herb list and the licorice (kanzo) amount.
Never use a product whose label names Aristolochia, guan mu tong, or mu tong of unknown source. Japanese akebia stem is the safe one.
The formula grew out of Chinese medical books of the 1500s and 1600s, where it is known as Long Dan Xie Gan Tang. Japanese doctors took it up and shaped their own version by the 1700s.
It is now a staple of Kampo practice and sits on Japan's insurance-covered list of 148 formulas. Because it is classical in both Chinese and Japanese practice, its traditional standing is high.
Stop taking it and see a doctor the same day if your ankles or face swell, you gain weight fast, your muscles cramp or feel weak, or your heart pounds or skips.
Get urgent care if you feel faint, cannot catch your breath, or have a new cough with fever.
Also see a doctor if your skin or the whites of your eyes turn yellow, your urine turns dark, or you get a spreading rash. Book a normal appointment if your symptoms have not improved after four weeks, or if you have fever, back pain or blood in your urine at any point.
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 Ryutanshakanto 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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