What is Choyoto?

Choyoto is a Kampo herbal formula taken as a tea-like granule or powder. It is used mainly for long-running headaches, dizziness and stiff shoulders in middle-aged and older people, often in those who also have high blood pressure.

Kampo is Japan's own school of herbal medicine, built on old Chinese texts and reshaped by Japanese doctors. Choyoto is on the Japanese health ministry (MHLW) list of 148 Kampo formulas that national health insurance covers. In Japan a doctor or pharmacist can supply it as a licensed medicine, not just a supplement.

Japanese sources also romanise this formula's name as Chotosan. Both names point to the same blend, built around chotoko (Uncaria hook), and you may see either spelling on a package.

The honest evidence picture: this formula has a long record of use in Kampo practice, but only a small amount of human trial data, and the studies are old and small. Long traditional use is not proof that a remedy works. That point applies to everything on this page and is not repeated below.

How does Choyoto work?

Kampo does not treat a formula as one drug with one target. The classical idea is that Choyoto settles "rising" heat and wind in the head, which in old language covers throbbing morning headache, dizziness and a short temper.

In modern terms, the ingredients have been studied mostly in test tubes and animals. Laboratory work suggests the Uncaria hook alkaloids may relax blood vessel walls and may calm nerve cells. This is background, not proof that the same thing happens in your body.

Small Japanese studies have looked at blood flow in the brain after Choyoto, but they were short and involved few people. No one has shown a clear, confirmed mechanism in humans. Treat any explanation you read, including this one, as a working idea.

What forms does Choyoto come in?

The usual form is a dried water extract turned into fine granules or powder, sold in single-dose sachets. This is the form used in Japanese hospitals and the form most trials used.

You stir the granules into hot water and drink them, or swallow them with warm water. Some people find the taste bitter and slightly sweet from the licorice.

Tablets and capsules of the same extract exist and suit people who dislike the taste. A few practitioners still boil the raw sliced herbs into a decoction (a strong tea), but this is uncommon outside specialist clinics.

Strength can differ between makers, so check the label and do not assume two brands match dose for dose.

Where it comes from:

Choyoto comes from a Chinese Song dynasty text, the Benshi Fang, written in the 1100s. Japanese doctors took it up and it became a standard part of Kampo practice.

In Japan it has long been given to older patients with morning headache, ringing ears, dizziness and a quick temper. It sits today on the national insurance list of 148 approved Kampo formulas.

What does Choyoto help with?

• Long-running headache in middle-aged and older adults: This is the classic use. Kampo doctors pick Choyoto for a dull headache that is worst in the morning, often in someone with high blood pressure. Human proof is thin. We found no good placebo-controlled trial for headache alone, so this rests on practice reports, not hard data.
• Dizziness and light-headedness: Dizziness sits next to headache in the old descriptions of who this formula suits. It is a common reason Japanese doctors choose it. We found no controlled human trial that tested Choyoto for dizziness on its own. New or sudden dizziness needs a doctor, not a herb.
• Stiff, tight shoulders and neck: Stiff shoulders are part of the classic picture that points to this formula. Relief is described in practice notes, not measured in trials. There is no human trial we can point to for this use.
• Ringing in the ears (tinnitus): Old texts list ringing in the ears among the head symptoms this formula was used for. Modern support is weak. We found no trial in people that tested Choyoto for tinnitus.
• Irritability and poor sleep in older adults: Kampo texts describe this formula for an older person who is tense, short-tempered and sleeps badly. The old wording is "rising heat". No trial we can identify has tested mood or sleep as a main outcome.
• Day-to-day symptoms of vascular dementia: This is the one use with any trial data. A small Japanese study in the 1990s compared Choyoto with a dummy powder in older adults with vascular dementia and reported better scores on some daily-living and mood measures. The study was small and old, and no large trial has confirmed it. This is not a treatment for dementia and it does not stop the illness from getting worse.

Which foods are rich in Choyoto?

1. Licorice sweets and licorice tea: they add to the licorice already in the formula
2. Salty foods: extra salt worsens the swelling and blood pressure rise licorice can cause

Practical Tips:

Choyoto is a medicine, not a food; the items above are things to cut back on while you take it.

What are the side effects of Choyoto?

• Nausea, loss of appetite or stomach discomfort
• Loose stools or belly pain
• Skin rash, redness or itching
• Swollen ankles, feet or face, and sudden weight gain (a licorice effect)
• Rising blood pressure
• Muscle weakness, cramps or an odd heartbeat from low potassium (a salt your muscles and heart need)
• Rare but serious: liver injury, shown by yellow skin or eyes, dark urine and deep tiredness
• Rare but serious: interstitial pneumonia (lung inflammation), shown by a dry cough, fever and breathlessness

Good to know:

Most people who take Choyoto have no trouble, and mild stomach upset or rash are the usual complaints. The serious effects are rare but real, and they are why this page is not marked routine.

The main watch-point is kanzo (licorice). Licorice can cause pseudoaldosteronism (a licorice reaction that pushes blood pressure up and drives potassium down), which shows up as swelling, weight gain, muscle weakness and cramps.

Risk rises with higher doses, longer use, older age, and when you take more than one licorice-containing Kampo formula at once. Report swelling, cramps or new breathlessness to a doctor rather than waiting it out.

How much Choyoto should you take?

• Recommended daily: In Japan the standard adult dose of the granule extract is 7.5 g a day, split into two or three doses. Some products use 6 g a day. Follow the label or your prescriber, because strength differs between makers. There is no separate dose set outside Japan, and no dose has been tested in large trials. Older, smaller or frailer people are often started lower. Do not take it alongside another Kampo formula that also contains kanzo (licorice) unless a prescriber has checked the total licorice load.
• Best time of day: Usually split across the day: morning, midday and evening, or morning and evening if you take two doses. Some people take the morning dose early because the target headache is often worst on waking.
• With or without food: Kampo granules are traditionally taken before meals or between meals, with warm water. If this upsets your stomach, taking them with food is acceptable and unlikely to spoil the effect.
• Time to effect: Some people notice less headache or dizziness within one to two weeks. Changes in sleep, mood or daily function in the dementia study took several weeks to appear. If four weeks bring nothing, it is unlikely to start working later.
• How long to take it: Give it two to four weeks for headache, dizziness or stiff shoulders, then judge honestly whether anything has changed. If nothing has, stop. The dementia study ran for about twelve weeks. Long-term daily use raises the licorice risk, so anyone taking it for months should have blood pressure and blood potassium checked.