What is Saibokuto?

Saibokuto is a Kampo herbal formula. Kampo is the Japanese form of herbal medicine. The formula blends ten herbs and is taken as granules, tablets or a hot tea.

In Japan it is used for wheeze, a tight chest, a nervous cough, and the feeling of a lump in the throat. Doctors there may add it to normal asthma care. It is one of the 148 Kampo formulas that Japan's Ministry of Health, Labour and Welfare (MHLW) approves for the national health insurance (NHI) list.

Long use in Kampo is not proof that a remedy works, and that point is made here once for the whole page. The human trial evidence for Saibokuto is thin: a few small, old Japanese studies in asthma, and no large modern trials. It also carries real risk to the lungs and liver, so it is not a casual self-care herb.

How does Saibokuto work?

No one has shown how Saibokuto works in the body. The rest is theory and lab work.

Two of its herbs hold well-studied plant chemicals. Baicalin from ogon (Chinese skullcap) and saikosaponins from saiko (bupleurum root) calm inflammation (swelling and irritation in tissue) in test tubes and in animals. Some lab work hints that the mix damps the cells that drive allergy in the airway.

In Kampo theory, the formula is said to move "stuck energy" in the chest and throat and to settle a cough tied to stress. That is a traditional model, not a tested one. None of it proves the formula opens airways in people.

What forms does Saibokuto come in?

The usual form is a dried water extract made into granules or fine powder in single-dose sachets. This is the form used in Japan under the insurance list, often labelled TJ-96 or a similar product code.

Tablets and capsules of the same extract are also sold. A few practitioners still brew the raw herbs as a hot tea (decoction).

Strength is not the same across brands. A granule sachet is far stronger than a home-brewed cup of the same weight of herbs.

Where it comes from:

The formula comes from Japan, built from two much older Chinese recipes.

Shosaikoto and Hangekobokuto both trace to Chinese texts from around 200 CE. Japanese doctors began to pair them, and the paired form took the name Saibokuto. It became a set formula in Kampo practice in the Edo period.

It entered modern Japanese medicine in the 20th century as a standard extract. It is still prescribed there today, mostly for cough, wheeze and throat tightness.

What does Saibokuto help with?

• Asthma (as an add-on, not a replacement for inhalers): This is the main use studied in people, and the studies are small and old. Japanese groups reported that adults who needed steroid tablets had fewer symptoms while taking the formula, and some cut their steroid dose. The studies were small and mostly not blinded, so the result is weak. Never use it in place of an inhaler or a steroid your doctor gave you. Never stop asthma medicine to try it. Talk to the doctor who treats your asthma first.
• Long-lasting dry cough after a cold: This is a traditional use, not a proven one. Kampo practice reaches for Saibokuto when a cough drags on after the infection has gone and the chest feels tight. We found no good human trial for this use. A cough that lasts more than three weeks needs a doctor, not a herb.
• Feeling of a lump in the throat (globus): One of the two parent formulas, Hangekobokuto, has been used for this for centuries, and Saibokuto carries that use forward. It is a classic Kampo picture: a throat that feels blocked, but nothing is found there. Human trial support is very limited. A lump feeling with trouble swallowing, weight loss or a hoarse voice must be checked by a doctor.
• Chest tightness linked to stress or worry: Traditional use only. Kampo texts describe the formula for a chest that feels blocked and a mood that feels stuck. There is no reliable human trial showing it helps anxiety. Do not use it in place of care for a mental health problem.
• Bronchitis (irritated airways) with a stubborn cough: Used in Japan as a second-line helper when a cough with wheeze lingers. Support comes from practice and from lab work on inflammation, not from strong trials. Fever, coloured phlegm, chest pain or breathlessness mean you need medical care, not a herb.

Which foods are rich in Saibokuto?

1. Licorice sweets: they add more of the same licorice compound that is already in the formula
2. Licorice root tea and many herbal blends: check the label, as licorice is a common sweetener
3. Some soft drinks and sweets flavoured with licorice extract: the amount is small but it adds up with daily use

Practical Tips:

Saibokuto is a medicine, not a food. The foods above matter only because they add to its licorice load.

What are the side effects of Saibokuto?

• Nausea, loss of appetite or an upset stomach
• Diarrhoea or belly cramps
• Rash, itching or hives
• Swollen ankles, weight gain or a rise in blood pressure
• Muscle weakness, cramps or an odd heartbeat, from low potassium
• Dry cough, breathlessness or fever, which can mean interstitial pneumonia (inflammation deep in the lung tissue)
• Yellow skin or eyes, dark urine or deep tiredness, which can mean liver injury

Good to know:

Mild stomach upset and rash are the common problems, and they settle when you stop.

Two rare reactions are serious. Formulas that contain saiko, including this one, have been linked to interstitial pneumonia (inflammation deep in the lung tissue) and to liver injury. Deaths have been reported, mostly in people with hepatitis C liver disease or people taking interferon.

The licorice in the mix can cause pseudoaldosteronism (a licorice reaction that pushes potassium down and blood pressure up, and can swell the ankles). This is more likely with higher doses or long use. Stop the formula and get medical advice if any of these signs appear.

How much Saibokuto should you take?

• Recommended daily: There is no dose set outside Japan. In Japan, the standard adult amount of the dried extract granules is about 7.5 g a day, split into two or three doses. Products differ a lot in strength. Follow the label on the product you hold, or the amount your prescriber gives you. Doses for children are set by a doctor by age and weight. Do not work one out yourself.
• Best time of day: Split the day's amount into two or three doses, spread out from morning to evening. Take the last dose well before bed if it upsets your stomach.
• With or without food: The Japanese custom is to take it on an empty stomach, about 30 minutes before a meal or between meals, with warm water. If it makes you feel sick, take it with a little food instead.
• Time to effect: Stomach and throat symptoms may ease within a few days. In the asthma studies, changes took several weeks to a few months.
• How long to take it: Use it for a short, set stretch and then review. Four weeks is a fair first check point. If nothing has changed by then, stop. Long use raises the risk from the licorice in the mix, so anyone taking it for months should have blood pressure and potassium checked by a doctor.