What is Jiinkokato?

Jiinkokato is a set herb mix used in Kampo, the herbal medicine of Japan. It is a single drug (Kampo). That means it is one fixed mix, taken on its own, rather than blended with other mixes.

Its old name is Yin-Nourishing Fire-Descending Decoction. Kampo uses it for a dry cough that has gone on for weeks or months. The cough is often worse at night, with little or no phlegm.

The proof is weak. The mix has a long past in Kampo, but we found no good human trials for it. A long history of use is not proof that a herb works.

How does Jiinkokato work?

No one has shown how Jiinkokato works in the body. What follows is theory, not proof.

Kampo reads this kind of cough as yin deficiency (a dry, worn-out state with too little body fluid). The mix is meant to add moisture and cool that dryness. The moistening herbs are rehmannia, asparagus root and ophiopogon.

Lab tests hint that some of these herbs calm coughing and soothe dry tissue. That work is in cells and animals only. It does not show that the whole mix helps people.

What forms does Jiinkokato come in?

In Japan the common form is a dried extract granule, sold in sachets. Tablets, capsules and loose powder are also made.

The oldest form is a decoction (a tea made by boiling the raw herbs in water for about 30 minutes). Some Kampo practitioners still prepare it this way.

Strength differs a lot between makers. Check the label for how much licorice each daily dose holds.

Where it comes from:

The recipe comes from a Chinese text of 1587, Wanbing Huichun, written by Gong Tingxian. Japanese doctors took it up during the Edo period and it became part of Kampo practice.

It was long given to people with a dry, wasting cough, including cough from tuberculosis in the years before drug treatment. Today it is one of the Kampo extract mixes approved and sold in Japan.

What does Jiinkokato help with?

• Long-lasting dry cough: This is the main Kampo use, and it is a long-standing one. Kampo picks the mix for a dry, tickly cough with little phlegm in someone who seems dry and run-down. We found no controlled human trial that tests it against a dummy treatment for this cough.
• Cough that is worse at night: Night cough is part of the classic picture Kampo doctors look for before choosing this mix. The support here is case reports and practitioner experience in Japan, not trial data. A new or worsening night cough needs a doctor's check first.
• Dry throat and hoarse voice: The moistening herbs are meant to ease throat dryness that goes with the cough. This use rests on tradition. No trial has measured throat dryness or voice quality with this mix.
• Cough that lingers after a cold or chest infection: Japanese practitioners sometimes use it when a cough drags on for weeks after an infection and has turned dry. Reports of this are informal. A cough lasting more than three weeks should be looked at by a doctor before you self-treat.

Which foods are rich in Jiinkokato?

1. Licorice sweets and licorice tea: they hold the same licorice compound as this mix, so they add to your total
2. Some soft drinks, herbal teas and chewing tobaccos flavoured with real licorice — check labels for licorice or glycyrrhizin

What are the side effects of Jiinkokato?

• Upset stomach, nausea or loss of appetite
• Loose stools
• Rash or itching
• Swelling in the face, hands, ankles or legs
• Weight gain from held-in fluid
• Raised blood pressure
• Low potassium (a blood salt your muscles and heart need), which can cause muscle weakness, cramps or an odd heartbeat
• Rarely, liver injury, seen as yellow skin or eyes, dark urine or deep tiredness
• Rarely, lung inflammation, seen as new breathlessness, a dry cough that suddenly gets worse, or fever

Good to know:

Most people who take it have no trouble, and stomach upset is the most common complaint. The serious effects are rare but real.

The main one to watch is pseudoaldosteronism (a licorice side effect that raises blood pressure, holds in fluid and lowers potassium). It builds up slowly over weeks to months of use.

Stop taking it and speak to a doctor if you swell up, gain weight fast, feel weak in the muscles, or notice your heart racing or skipping.

How much Jiinkokato should you take?

• Recommended daily: There is no dose proven by trials. The usual Japanese label dose for adult extract granules is about 7.5 g a day, split into two or three doses. If you boil the raw herbs, a practitioner sets the amount for you. Doses for children and older adults are lower and should be set by a prescriber. Never take it at the same time as another licorice-containing Kampo mix or licorice supplement unless a doctor has added up the total licorice for you.
• Best time of day: Split the day's amount into two or three doses, spread through the day. Many Kampo users take the last dose in the evening when night cough is the problem.
• With or without food: Kampo extracts are usually taken before meals or between meals, with warm water. If it upsets your stomach, take it with food instead.
• Time to effect: Any change is usually slow. People who find it helpful often report it over one to three weeks, not in a day.
• How long to take it: Give it two to four weeks, then take stock. If your cough is no better, stop and see a doctor. Long runs raise the risk of licorice side effects. If you stay on it for months, ask your doctor to check your blood pressure and your blood potassium.