What is Rikkosan?

Rikkosan is a Japanese Kampo herb formula. It is used mainly for toothache and other mouth and gum pain. In Japan, dentists prescribe it most often.

It is one of the 148 Kampo formulas that Japan's national health insurance will pay for. That list is run by the MHLW (Ministry of Health, Labour and Welfare).

You usually take it as a granule powder mixed into warm water. Many practitioners tell you to hold the liquid in your mouth. Keep it on the sore spot for a short time, then swallow it.

Honest verdict on the evidence: Rikkosan has a long record of use in Kampo dentistry. But we could not find a published randomised controlled trial in humans. Traditional standing and proof of effect are two different things, and long use does not by itself show that something works.

Rikkosan holds licorice root. Licorice can raise blood pressure and lower potassium. Doctors call this pseudoaldosteronism (a salt and water problem that drops your potassium).

So this formula is not a casual everyday remedy. Read the safety section below before you use it.

How does Rikkosan work?

In Kampo terms, Rikkosan is said to clear "heat" and move stagnation in the mouth and face. Practitioners link this to throbbing tooth pain and swollen gums.

In modern terms, the proposed reasons are still unproven. Asiasarum root (saishin) holds volatile oils. These can make the mouth lining feel numb and tingly, which may be why the liquid is held in the mouth.

Lab and animal work has looked at the single herbs. It has tested anti-inflammatory (swelling-reducing) and local pain-blocking actions. That work does not tell you what the whole formula does in a person with toothache.

What forms does Rikkosan come in?

Common forms:

Dried extract granules in single-dose sachets. This is the standard prescription form in Japan.

Extract tablets or capsules, sold by some makers.

Traditional decoction, where the raw herbs are simmered in water. This form is rare outside specialist practice.

The granules are usually mixed into hot water and cooled first. That way you can hold the liquid in your mouth.

Where it comes from:

Rikkosan comes from Lanshi Micang, a Chinese medical text. It is credited to Li Dongyuan in the 13th century.

The name means roughly "the powder that works at once". That is a claim about speed made by its authors, not a finding from testing.

Japanese Kampo practitioners took it up. They narrowed its use to dental and mouth pain. It stays on the MHLW list of 148 Kampo formulas, and it is a familiar prescription in Japanese dental care.

What does Rikkosan help with?

• Toothache: This is the classic use and the reason most Japanese dentists reach for it. Traditional practice is strong here; published human trial evidence is not. Rikkosan does not treat the cause of a toothache. A decayed tooth, cracked tooth or infection still needs a dentist.
• Gum pain and swelling: Used in Kampo for hot, throbbing, swollen gums. Support is traditional practice and clinical experience reports rather than controlled trials. Bleeding or swollen gums that last more than a week need dental assessment.
• Pain after dental treatment or tooth extraction: Sometimes prescribed in Japan alongside or instead of standard painkillers after dental work. We could not find a randomised trial comparing it with a placebo or with a standard painkiller. Tell your dentist if you plan to use it.
• Burning mouth and tongue pain (glossodynia): A reported Japanese use, discussed mainly in case reports and small clinical series. The evidence is weak and this symptom has many possible causes, including nutrient deficiency and nerve problems, so it deserves a proper diagnosis first.
• Facial and jaw pain of dental origin: Used traditionally when pain spreads from a tooth into the jaw or cheek. Evidence is traditional only. New, severe or one-sided facial pain should be checked by a doctor or dentist rather than self-treated.

Which foods are rich in Rikkosan?

1. Licorice sweets and licorice root tea: they contain the same glycyrrhizin that drives the blood pressure and potassium effects
2. Some herbal cough syrups and throat lozenges: licorice is a common ingredient

Practical Tips:

While you are taking Rikkosan, keep licorice sweets and licorice tea to a minimum so the total dose does not add up.

What are the side effects of Rikkosan?

• Rising blood pressure
• Swelling of the ankles, legs or face from fluid retention
• Low potassium, which can cause muscle weakness, cramps and tiredness
• Headache
• Nausea or stomach upset
• Numb or tingling mouth from the Asiasarum root
• Allergic skin rash or itching
• Rarely, rhabdomyolysis (severe muscle breakdown that can damage the kidneys)

Good to know:

Most people who take Rikkosan for a few days have no trouble. The effects that matter come from licorice root, and they build up with dose and time rather than appearing suddenly.

The pattern doctors watch for is called pseudoaldosteronism: blood pressure climbs, potassium falls, and you feel weak or swollen. It is uncommon at short-term doses but well documented with licorice-containing Kampo formulas, and it is more likely in older people, in those on water tablets, and in anyone already taking another licorice-containing product.

How much Rikkosan should you take?

• Recommended daily: In Japan the usual dose is about 7.5 g of the dried extract granules a day. You split this into two or three doses. Some products use a lower daily amount, so follow your product label. A common instruction is to dissolve one sachet in hot water. Let it cool to a comfortable warmth. Hold it in your mouth near the sore tooth for a short time, then swallow. No dose has been set outside Japanese prescribing practice. No dose has been set for children.
• Best time of day: Spread the doses through the day. Morning, midday and evening works well. You can also take it when the pain is worst.
• With or without food: Kampo granules are taken before meals or between meals, on a fairly empty stomach. If it upsets your stomach, take it with a little food.
• Time to effect: Users and practitioners often report less tooth pain within minutes to an hour. That is after holding the liquid in the mouth. Controlled trials have not confirmed this.
• How long to take it: Rikkosan is meant for short bursts of use. That usually means a few days around a painful episode. It holds licorice, so long unbroken use raises the risk of high blood pressure and low potassium. Stop and see a dentist if your pain has not clearly eased within a few days. Do not take it for weeks on end unless a practitioner checks your blood pressure and potassium.