What is Shoma?

Shoma is the dried root of a plant called Cimicifuga simplex. It is a single herb in Kampo, the old herb system of Japan. Its Latin name is Cimicifuga simplex, and it is also sold as Cimicifuga Rhizome.

It is used at the very start of a fever or a chill. Kampo says Shoma brings out sweat and "raises yang". In plain words, it is meant to lift low energy and push a new illness out through the skin.

Older texts also use it for sore throat, mouth sores, skin rashes and piles (swollen veins around the back passage). Now the verdict on proof: Shoma has a long record of use, but almost no human trials back it up. Long use is not proof that a herb works, and this page keeps the two apart.

How does Shoma work?

Honest answer first. No one has shown how Shoma works in a sick person.

Lab tests on Cimicifuga roots find plant acids and soap-like compounds. In test tubes and in animals, some of these damp down swelling and slow the growth of germs. That is a long way from proof in people.

Kampo explains it in its own way. It says the root opens the surface of the body, brings out sweat, and lifts qi (the flow of life energy) that has sunk. This is a way of thinking about the body, not a measured drug effect.

The sweating effect is the one thing users report often. Even that has not been checked in a proper human trial of Shoma on its own.

What forms does Shoma come in?

Shoma is sold as a dried, sliced root. Most people meet it inside a ready-made Kampo formula rather than on its own.

The usual forms are dried root slices for simmering into a tea, and granules or powder in single-dose packets. Packets are the standard form in Japan. Tablets and capsules of powdered root are also sold.

Check the label for the Latin name Cimicifuga simplex. Some products use black cohosh (Cimicifuga racemosa), which is a different plant used for a different purpose.

Where it comes from:

Shoma is an old herb. The root is listed in the first Chinese herb classic, written about 2,000 years ago, where it is called sheng ma. Japanese doctors later took it into Kampo.

It is still an official crude drug in Japan. It appears in formulas such as Shomakakkonto, used for the first day of a fever with a rash, and Otsujito, used for piles.

Korean and Chinese herb systems use closely related Cimicifuga roots in much the same way. That shared use across traditions is why its traditional standing is strong, even though its test record is not.

What does Shoma help with?

• Early fever and chills: This is the main use. Kampo gives Shoma in the first day or two, to bring out sweat and ease chills. No human trial has tested Shoma alone for this.
• Sore throat: Traditional texts pair Shoma with cooling herbs for a raw, hot throat. Lab work hints at a calming effect on swelling. There is no human trial to support it.
• Mouth sores and gum soreness: A long-standing use in both Chinese and Japanese practice, often as a mouth rinse or in a mixed formula. Human evidence is missing.
• Skin rash in the first days of a feverish illness: Shomakakkonto was built for this pattern. Old texts say the herb helps a rash come out fully. This idea has not been tested in a modern trial.
• Piles (swollen veins around the back passage): Shoma appears in Otsujito for this. The Kampo idea is that it lifts tissue that has sagged. Trials of the whole formula are few and small, and none isolates Shoma.
• Feelings of heaviness or sinking, in Kampo terms: "Raising yang" is a Kampo pattern, not a medical diagnosis. Judge this as tradition only. There is nothing to measure here.

What are the side effects of Shoma?

• Upset stomach or nausea
• Loose stools
• Headache
• Dizziness
• Heavy sweating and thirst
• Skin rash or itching
• Rare liver injury, reported with the close relative black cohosh

Good to know:

Most complaints are mild and stop when you stop the herb. Upset stomach and headache are the usual ones.

Serious harm looks rare, but Shoma on its own has not been tested well in people, so the true rate is unknown.

A close relative, black cohosh, has rare reports of liver injury. Treat yellow skin or eyes, dark urine, or pain under your right ribs as urgent. Stop the herb and get checked.

How much Shoma should you take?

• Recommended daily: No dose has been proven by trials. What follows is what tradition uses. Old Chinese and Japanese texts use about 1 to 3 grams of the dried root a day. The root is simmered in water and the tea is split into two or three doses. In Japan, Shoma is nearly always one herb inside a mixed formula, so the dose comes set by the maker. Follow the packet, and let a trained herbalist set any other amount.
• Best time of day: Take the first dose as soon as the chill or fever starts. Kampo teas are drunk warm, two or three times a day, spread out from morning to evening. Avoid a dose late at night if sweating keeps you awake.
• With or without food: Kampo teas are usually taken between meals, on an empty stomach. If it upsets your stomach, take it with a little food. Drink water through the day, since sweating loses fluid.
• Time to effect: Not known from trials. Tradition expects sweating and easier chills within a few hours of the first dose. If nothing changes in three days, stop.
• How long to take it: Short term only. Shoma is a herb for the first days of an illness, not a daily supplement. Most Kampo use runs three to five days. If you feel no better after three days, stop and see a doctor. Do not run it for weeks on end. Long use has not been studied, and the liver worry with related plants makes long use unwise.