What is Keishito?

Keishito is a herbal formula from Kampo, the traditional medicine of Japan. Its other name is Cinnamon Twig Decoction, a decoction being a tea made by boiling herbs. In Kampo it counts as a single drug: one fixed recipe of five herbs, taken as a whole.

It is used at the very start of a cold or chill in a person who feels weak and sweats without effort. Typical signs are a mild fever, a headache, a stiff neck, and a strong dislike of wind and cold.

Its traditional standing is old and strong. The human trial evidence is thin: we could not find a published randomised trial of Keishito itself. Long use in a tradition is not proof that a remedy works.

How does Keishito work?

The short answer is that nobody has shown how it works in people.

In Kampo thinking, cinnamon twig warms the body and helps a light sweat break the chill. Peony root is said to hold the body's fluids in, so the sweating does not run away with your strength. Ginger, jujube and licorice are there to settle the stomach and tie the formula together.

In the laboratory, single herbs from the formula do things that look useful. Cinnamon and ginger compounds affect fever and inflammation (swelling and heat in body tissue) in animals. None of that has been shown to explain any effect of the whole formula in a person with a cold.

What forms does Keishito come in?

Most people in Japan take Keishito as a dried granule powder made by a licensed maker. It is stirred into hot water and drunk warm.

Other forms are tablets, capsules, and the old-style decoction, where the raw herbs are simmered in water at home. Granules are the usual form because the dose is steady and easy to measure.

Where it comes from:

Keishito comes from the Shanghan Lun, a Chinese medical text written around 200 CE, where it is called Gui Zhi Tang. It is one of the first formulas in the book and one of the best known in East Asian herbal practice.

Japanese doctors took it up centuries ago, and it became a staple of Kampo. Today it is made to a standard recipe in Japan and is covered by national health insurance.

What does Keishito help with?

• Early common cold with sweating and chills: This is the classic use, and Kampo practitioners reach for it in the first day or two of symptoms. The picture they look for is a person who is already sweating a little and feels weak, rather than someone hot, dry and strong. We found no randomised trial testing whether it shortens a cold.
• Mild fever with a dislike of wind and cold: Tradition says it suits a low fever with shivering, not a high fever. Evidence in people is lacking. A fever above 39C (102F), or one lasting more than three days, needs a doctor, not a herbal formula.
• Headache at the start of a cold: A dull head and a pulling feeling at the back of the neck are part of the classic pattern. This is traditional practice only. No trial has tested Keishito against a dummy treatment for headache.
• Stiff neck and shoulders during an early cold: Texts describe stiffness from the back of the head down to the shoulders. Practitioners treat this as a sign the formula fits, not as a separate illness. There is no human trial support.
• Feeling weak and cold while getting over an illness: Kampo uses this formula for people it describes as weak in constitution who feel cold and sweat easily. This is a judgement made by a practitioner, not a diagnosis. Evidence here is limited to tradition and case reports.

Which foods are rich in Keishito?

1. Cinnamon: the same spice family as the twig used in the formula, but a different plant part and a much smaller dose
2. Ginger: a kitchen root and one of the five herbs
3. Jujube (red date): eaten as a dried fruit across East Asia
4. Licorice sweets and licorice tea: a real source of glycyrrhizin that adds to your total

Practical Tips:

Food amounts of these spices are not the same as a medicinal dose, but licorice sweets and tea do count towards your licorice total.

What are the side effects of Keishito?

• Upset stomach or nausea (feeling sick)
• Loss of appetite
• Skin rash, redness or itching
• Heavier sweating than you wanted
• Swelling in the face, hands or ankles
• A rise in blood pressure
• Muscle weakness or cramps from low potassium
• Rare: liver injury, shown by yellow skin or eyes, dark urine and tiredness
• Rare: lung inflammation (swelling in the lungs), shown by a new dry cough, fever and breathlessness

Good to know:

Most people who take Keishito for a few days have no trouble. Mild stomach upset or a rash are the usual complaints.

The main risk comes from the licorice in it, and that risk grows with dose and length of use. Licorice can raise blood pressure, make the body hold water, and drop your potassium. Rare reports link licorice-containing Kampo formulas to liver injury and to lung inflammation.

Stop taking it and call a doctor if you notice swelling, muscle weakness, cramps, yellow skin, or a new cough with breathlessness.

How much Keishito should you take?

• Recommended daily: There is no dose set by trial evidence. In Japan, a common adult dose of standard granules is 7.5 g a day, split into two or three doses. Doses for children are lower and depend on age and weight. Ask a pharmacist or a doctor who knows Kampo. Follow the label on the product you actually hold, since strengths differ between makers.
• Best time of day: Usually before meals or between meals, spread across the day. The first dose is often taken as soon as the chill starts, and tradition says to rest and keep warm afterwards.
• With or without food: Take it on an empty stomach, about 30 minutes before a meal, with warm water. If it upsets your stomach, take it with a little food instead.
• Time to effect: If it helps at all, the effect is meant to be quick: within a few hours to a day. Classic texts say the first dose should bring a light sweat and ease the chill.
• How long to take it: For a cold, this is a short-term formula. Kampo practice is a few days at most, and often just one or two days. If you feel no better after two or three days, stop and see a doctor. Do not take it for weeks on end. Long use raises the risk of the licorice side effects listed below.