What is Ryokeijutsukanto?

Ryokeijutsukanto is one of the older prescriptions in East Asian medicine, recorded in the Han-dynasty texts attributed to Zhang Zhongjing and carried into Japan, where it became one of the extract formulas covered by national health insurance (commonly numbered 39). Its name is simply a list of its four ingredients: ryo (poria), kei (cinnamon bark), jutsu (atractylodes rhizome) and kan (licorice).

In traditional terms it is a formula for suidoku — a pattern of 'water imbalance' in which fluid is thought to pool in the upper body and stomach, producing dizziness on standing, a fluttering sensation below the ribs, light-headedness, a heavy head and sometimes a fine tremor. Japanese doctors reach for it most often in young people with orthostatic dysregulation, in adults with chronic non-spinning dizziness, and as an adjunct in Ménière's-type complaints.

What it is not is a well-trialled drug. The formula's reputation rests on a very long clinical record in Japan and China rather than on large randomised studies; published human research is mostly small, Japanese-language, and often open-label. It is also a licorice-containing formula, which means it carries a real, dose- and duration-dependent risk of low potassium and raised blood pressure that should be monitored rather than ignored.

How does Ryokeijutsukanto work?

Traditionally it is described as warming the middle burner and moving retained fluid downward and outward, which is the classical explanation for its use in dizziness and palpitations. In modern terms, the proposed mechanisms are speculative and largely from animal or laboratory work: mild effects on fluid handling and vestibular compensation, improved cerebral and peripheral circulation from cinnamaldehyde, diuretic and anti-inflammatory activity from poria triterpenes, and gastric motility effects from atractylodes. Glycyrrhizin from licorice inhibits the enzyme 11β-hydroxysteroid dehydrogenase type 2 in the kidney, which is both a plausible contributor to fluid and blood pressure effects and the reason the formula can cause pseudoaldosteronism.

What forms does Ryokeijutsukanto come in?

In Japan the standard product is a hot-water extract dried into granules, dispensed in 2.5 g sachets and taken three times daily. Extract tablets and capsules exist for people who dislike the taste. Traditional practitioners may prescribe the raw herbs as a decoction, typically poria 4–6 g, cinnamon bark 3–4 g, atractylodes 3 g and licorice 2 g per day, simmered in water. Granules are the most consistent form and the one used in most Japanese clinical reports; loose-herb decoctions vary more in strength, and the licorice dose is harder to track when combining formulas.

Where it comes from:

The formula appears in the Jingui Yaolue and Shanghan Lun, compiled around the third century CE, where it is indicated for fullness below the heart, dizziness on rising and shortness of breath from retained fluid. It passed into Japanese medicine with the wider Chinese canon and was refined by the Edo-period koho ('classical formula') school, which favoured simple, small prescriptions matched tightly to observable patterns. Since 1976 it has been available in Japan as a standardised extract reimbursed by national health insurance, which is why most modern reports on it come from Japanese ENT, paediatric and internal medicine clinics.

What does Ryokeijutsukanto help with?

• Dizziness and light-headedness: This is the formula's core traditional indication and the one with the most human data behind it — though that data is modest. Japanese ENT and internal medicine clinics have published small open-label studies and case series reporting reduced dizziness scores in people with chronic non-spinning light-headedness, often after 2–4 weeks. There are very few placebo-controlled trials, and the ones that exist are small. The honest position is that it is plausibly helpful for mild chronic dizziness, and it is widely used for it in Japan, but the effect size has not been reliably established.
• Orthostatic dysregulation and dizziness on standing: Ryokeijutsukanto is one of the standard Kampo choices for orthostatic dysregulation in Japanese adolescents — the pattern of morning dizziness, difficulty getting out of bed, headache and palpitations. Paediatric case series and small clinical reports describe improvement in symptom scores, sometimes alongside lifestyle measures like salt and fluid intake. There are no large controlled trials. Because fainting on standing can also reflect anaemia, heart rhythm problems or autonomic disease, a proper medical assessment should come first rather than after.
• Palpitations and chest fluttering: The classical text describes 'throbbing below the heart' as a target symptom, and Kampo practitioners use the formula for benign palpitations associated with anxiety or fluid imbalance. Human evidence here is essentially anecdotal and case-based. Palpitations are also a symptom that needs to be taken seriously: new, frequent, or exertional palpitations, or any that come with fainting or chest pain, need an ECG and a doctor, not a herbal formula. Note too that the licorice in this prescription can lower potassium, which can itself provoke arrhythmia.
• Ménière's-type vertigo (adjunctive): Because Ménière's disease is understood in Kampo terms as a fluid problem in the inner ear, this formula is often given alongside conventional treatment such as betahistine or diuretics. Published support is limited to small Japanese studies and clinical experience reports; there is no good randomised evidence that it changes the course of the disease or preserves hearing. It should be regarded as a possible symptomatic adjunct only, and the diuretic combination in particular needs potassium monitoring because of the licorice.
• Tension-type headache with a heavy head: Traditional use covers headaches described as a heavy, foggy or waterlogged head, often worse in damp weather or on standing. This overlaps with tension-type headache and with the headache of orthostatic dysregulation. Clinical evidence specifically for headache is thin — mostly practitioner reports rather than trials. Other Kampo formulas such as goreisan are more commonly cited for headache with fluid imbalance, and a Kampo practitioner would choose between them on the basis of the whole symptom picture.
• Motion sickness: Some Japanese practitioners use Ryokeijutsukanto preventively for people prone to travel sickness, on the same 'excess fluid and unstable balance' reasoning as its use in dizziness. There is little formal human research on this indication, and conventional antihistamines have far better evidence. It is a reasonable thing to try under practitioner guidance if standard options are unsuitable, but it should not be presented as a proven anti-emetic.

What can Ryokeijutsukanto help prevent?

• Recurrent episodes of mild orthostatic light-headedness in people prone to them — used preventively in Japanese practice, though this is based on clinical experience rather than trial data
• Motion sickness in susceptible individuals when taken ahead of travel — traditional use, with little formal evidence

Which foods are rich in Ryokeijutsukanto?

There is no food that reproduces this formula, but a few dietary points matter alongside it. Avoid adding more licorice: licorice sweets, licorice-flavoured teas and confectionery, and other kanzo-containing herbal products all stack with the formula's glycyrrhizin and increase the pseudoaldosteronism risk. Keep potassium intake reasonable — bananas, potatoes, beans, leafy greens, avocado and yoghurt — since licorice pushes potassium down, though this is not a substitute for a blood test if you are using the formula long term. Very high salt intake works against the same pathway and is worth moderating, with the exception that people with orthostatic dysregulation are sometimes advised by their doctor to increase salt and fluids deliberately; follow the medical advice you have been given. Ginger, warm soups and regular meals fit the traditional 'warm the middle' logic of the formula. Alcohol tends to worsen both dizziness and fluid imbalance and is best kept low while you are assessing whether the formula helps.

What are the side effects of Ryokeijutsukanto?

• Pseudoaldosteronism from the licorice content: low blood potassium, raised blood pressure, ankle or facial swelling, weight gain from fluid, headache. Risk rises with dose, duration, older age, and use with diuretics
• Muscle weakness, cramps or, rarely, myopathy/rhabdomyolysis as a consequence of low potassium — stop and seek medical advice if you develop unexplained muscle pain or weakness
• Mild nausea, stomach discomfort or loss of appetite, particularly on an empty stomach
• Allergic reactions including rash and itching, occasionally to the cinnamon component
• Palpitations or flushing in sensitive people
• Rare reports, as with many Kampo formulas, of liver enzyme elevation and of interstitial pneumonia (persistent dry cough, breathlessness, fever) — both require prompt medical assessment

Good to know:

This is one of the milder licorice-containing Kampo formulas, with about 2 g of licorice per daily dose, and it is generally well tolerated in short courses. That does not make the licorice risk theoretical: pseudoaldosteronism is the single most common serious adverse effect reported with Kampo medicines in Japan, and it develops quietly. Anyone taking it for more than a few weeks should have blood pressure and potassium checked.

How much Ryokeijutsukanto should you take?

• Recommended daily: Standardised extract granules: typically 7.5 g per day, divided into two or three doses, which is the usual Japanese adult prescription. Decoction from crude herbs: roughly poria 4–6 g, cinnamon bark 3–4 g, atractylodes rhizome 3 g and licorice 2 g simmered as a daily amount. Children's doses are reduced by age and weight and should be set by a practitioner, not estimated at home.
• Best time of day: Traditionally taken two or three times daily spread across the day; people using it for morning dizziness or orthostatic symptoms often take the first dose shortly after waking.
• With or without food: Japanese practice is to take Kampo granules before meals or between meals, on a relatively empty stomach, ideally dissolved in hot water. If it causes nausea, taking it just after food is acceptable.
• Time to effect: Mild dizziness and light-headedness may ease within 1–2 weeks. Kampo practitioners generally review at 2–4 weeks and change formula if nothing has shifted.
• How long to take it: Short courses of a few weeks to a few months are typical. If you use it beyond about 4–8 weeks, blood pressure and serum potassium should be checked periodically because of the licorice. Do not run it indefinitely without review, and do not stack it with other licorice-containing Kampo formulas.