What is Nijutsuto?

Nijutsuto is a Kampo herbal formula from Japan. Nijutsuto is its Japanese romanised name, written 二朮湯. People take it for shoulder pain and for a stiff shoulder that is hard to lift or turn.

It sits on Japan's list of 148 Kampo formulas approved by the health ministry (MHLW) for national health insurance. A Japanese doctor can prescribe it. Elsewhere it is sold as granules or tablets.

It has been used this way for a long time. Long use is not proof that a medicine works. Human trials of Nijutsuto are few and small, so the honest answer is that we do not know how well it works.

How does Nijutsuto work?

No one has shown how Nijutsuto works in the body. What follows is the idea behind it, not proof.

In Kampo, this kind of shoulder pain is seen as 'dampness' and stuck flow in the joint. The formula is meant to dry that dampness, move fluid and warm the area so the pain lets go.

In modern terms, lab work on single herbs in it points to effects on swelling and muscle tone. Those are test-tube and animal findings. They do not tell you what happens in a person's shoulder.

What forms does Nijutsuto come in?

The usual form is a dried water extract turned into granules, packed in 2.5 g sachets. You stir a sachet into hot water and drink it.

Some makers press the same extract into tablets or fill it into capsules. These suit people who dislike the taste.

A few Kampo practitioners still boil the raw herbs into a tea. This is less common and the strength is harder to judge.

Where it comes from:

Nijutsuto first appears in a Chinese medical text of the Ming era, Wanbing Huichun (1587), known in Japan as Bankyo Kaishun.

Japanese Kampo doctors took it up and kept it for one main job: painful, stiff shoulders. It is still used that way today and is covered by Japanese national health insurance.

What does Nijutsuto help with?

• Frozen shoulder (a shoulder that is stiff and painful to move): This is the main use, and Japanese doctors prescribe it for exactly this. The evidence is mostly doctors' reports and small case series, not good trials. It is often used alongside physiotherapy (guided exercises), not instead of it.
• Shoulder pain in people aged 40 to 60: Kampo texts tie this formula to the shoulder pain that shows up in middle age. Tradition backs it well. Controlled human evidence is thin, so treat any benefit as unproven.
• Stiff, aching neck and upper back: Prescribers sometimes widen its use to neck and upper back stiffness that goes with the shoulder problem. This is an extension of traditional practice. We found no trial testing it for this.
• Shoulder pain that is worse in damp or cold weather: In Kampo this pattern is called 'dampness', and it is the pattern the formula is chosen for. Practitioners say it fits best here. There is no trial evidence comparing it with other formulas.
• Shoulder pain with a heavy or numb feeling in the arm: Traditional use includes a heavy arm and mild numbness along with the pain. New or spreading numbness needs a doctor first, because it can point to a nerve problem. Evidence for the formula here is traditional only.

Which foods are rich in Nijutsuto?

1. Licorice sweets and licorice tea: they add more glycyrrhizin on top of the kanzo already in the formula, so avoid them while you take it
2. Ginger: one of the herbs in the formula; normal food amounts are fine
3. Dried mandarin peel (chinpi): a seasoning in Japanese and Chinese cooking; food amounts are fine

Practical Tips:

Go easy on salty food and skip licorice sweets, as both add to the blood pressure and potassium risks.

What are the side effects of Nijutsuto?

• Upset stomach, nausea or loss of appetite
• Loose stools or belly discomfort
• Skin rash, itching or redness
• Swollen ankles, face or hands, and quick weight gain
• A rise in blood pressure
• Low potassium (a mineral your heart and muscles need), causing muscle weakness, cramps or an odd heartbeat
• Rare liver injury, with yellow skin or eyes, dark urine and deep tiredness
• Rare lung inflammation, with a dry cough, fever and shortness of breath

Good to know:

Most people take Nijutsuto without trouble. Mild stomach upset and skin rash are the common complaints, and they usually settle once you stop.

The serious effects are rare but real. Most come from the licorice (kanzo): a reaction called pseudoaldosteronism, meaning the licorice pushes blood pressure up and potassium down. Scutellaria (ougon) is linked to rare liver and lung harm.

Risk goes up with high doses, long use, older age, and taking other licorice products at the same time.

How much Nijutsuto should you take?

• Recommended daily: The usual adult dose in Japan is 7.5 g of the granule extract a day. You split that into two or three doses. Always follow the dose on your own product, since strengths differ between makers. Older adults and smaller adults often start lower. A doctor sets the dose for anyone under 18.
• Best time of day: Two or three times a day, spaced out. Many people take it morning, midday and evening.
• With or without food: Take it before meals or between meals, on a fairly empty stomach, with warm water. If it upsets your stomach, take it with a little food.
• Time to effect: Some people feel less pain within one to two weeks. Kampo prescribers usually judge the result at about four weeks.
• How long to take it: Give it about four weeks, then judge. If your shoulder is no better by then, stop and rethink the plan with a practitioner. If you take it for more than a few weeks, ask your doctor for a blood test that checks potassium. That is because of the licorice (kanzo) in it.