What is Ryutanshakanto?

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.

How does Ryutanshakanto work?

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.

What forms does Ryutanshakanto come in?

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.

Where it comes from:

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.

What does Ryutanshakanto help with?

• Burning or painful urination: This is the main reason Kampo doctors pick this formula. Texts back it strongly. Good human trials do not exist. See a doctor first. Pain when you pass urine is often an infection, and that needs the right test and drug.
• Cloudy or frequent urine: Kampo texts list this use. The support is tradition and case notes, not trials. Cloudy urine can point to an infection or a stone. Get it checked before you self-treat.
• Vaginal discharge: Both Chinese and Japanese texts use it here. We found no good human trial for this use. Thrush and other infections need proper tests. Do not delay care to try a herb.
• Itching in the groin or genitals: Tradition treats this as "damp heat" in the lower body, an old idea about heat and wetness. That is the basis for the use. There is no trial evidence. Itching that lasts needs a doctor's look.
• Long-term prostate irritation (chronic prostatitis): Some Japanese doctors add it to normal care for this. The reports are small and open-label, which means no dummy pill was used for comparison. So the effect is unproven. It is not a swap for medical care.
• Red, sore eyes or ear discharge (classical use): Old texts link these to the liver channel and use the formula for them. This is a record of tradition only. We found no human study. Eye and ear problems can get worse fast, so see a doctor.

Which foods are rich in Ryutanshakanto?

1. Licorice sweets and licorice tea: they add to the licorice already in the formula
2. Salty foods: extra salt adds to the swelling and blood pressure risk

What are the side effects of Ryutanshakanto?

• Upset stomach, loss of appetite or loose stools
• Swollen ankles, puffy face or fast weight gain
• Raised blood pressure
• Muscle cramps, weakness or aching
• Low potassium (low levels of a salt your heart and muscles need)
• Odd or fast heartbeat, linked to low potassium
• Rash or itching
• Liver injury, shown by dark urine, yellow skin or yellow eyes
• Lung inflammation (sore, swollen lungs) causing cough, fever and breathlessness

Good to know:

Mild stomach upset is the common one. The serious effects are rare but real, and most come from the licorice root (kanzo).

Licorice can hold salt and water and lower your potassium. That shows up as swelling, weight gain, cramps and high blood pressure. Left alone it can upset your heart rhythm.

Liver injury and lung inflammation have been reported with Kampo formulas that contain skullcap root (ogon). Both are rare. Both need a doctor the same day.

How much Ryutanshakanto should you take?

• Recommended daily: In Japan the usual adult dose of the extract granules is about 5 to 7.5 g a day, split into two or three doses. Makers differ, so follow the label or your prescriber. There is no set dose for self-care outside Japan. Keep track of the licorice (kanzo) amount, and count any other licorice you take.
• Best time of day: Split the day's amount into two or three doses, morning, midday and evening, as the label says.
• With or without food: Kampo granules are usually taken before meals or between meals, with warm water. If your stomach feels sore, take them with a little food.
• Time to effect: Some people notice a change in urinary comfort within a few days to two weeks. If two to four weeks bring nothing, stop.
• How long to take it: Use it short term. Check how you are doing after two to four weeks. If nothing has changed, stop and see a doctor. If you use it for more than a month, ask for a blood test to check your potassium (a salt your heart and muscles need).