Educational information, not medical advice — ask your doctor or midwife.
Zhi Zi Chi Tang is a two-herb Chinese formula. In English it is called Gardenia and Prepared Soybean Decoction. It is made from dried gardenia fruit (Zhi Zi) and fermented black soybean (Dan Dou Chi).
Chinese medicine uses it for what it calls leftover heat in the chest. In plain words: feeling hot, edgy and unable to sleep after a fever has passed. It is also taken for a tight, uneasy feeling in the chest.
This library treats the whole formula as a single drug entry. The evidence is thin: we could find no human trials of this formula. It has been used for about 1,800 years, but long use is not proof that a remedy works.
No one has shown how this formula works in people. What follows is the traditional idea, plus some lab findings.
In Chinese medicine, gardenia fruit is seen as cold and bitter. It is used to clear heat that leaves a person restless. Fermented soybean is seen as light and mild, and is used to lift leftover heat out to the surface.
In lab dishes and in animals, geniposide (the main gardenia compound) lowers markers of swelling. Some animal work also points to a calming effect. That work uses pure compounds, not the herb tea, so it does not show the same thing happens in you.
The classic form is a decoction. You boil the two herbs in water and drink the warm liquid.
You can also buy it as granules that melt in hot water, or as pills or capsules made from dried extract. These are easier to take but the strength varies from brand to brand.
Some shops sell the two herbs loose so you can cook them at home. Quality varies, and gardenia fruit is sometimes mixed up with other fruits. Buy from a seller who tests what they sell.
The formula comes from the Shang Han Lun (Treatise on Cold Damage), a Chinese medical text from about 200 CE. Its author, Zhang Zhongjing, wrote it for restlessness and poor sleep that hung on after a fever.
The same old text gives a warning. If the drink makes you vomit, stop taking it.
It is a small, plain formula and has stayed in use ever since. Later doctors added herbs to it for related problems. It is still taught in Chinese medicine schools today.
Stop taking it and see a doctor the same day if your skin or the whites of your eyes turn yellow, your urine goes dark, or you get pain under your right ribs. These can be signs of liver trouble.
See a doctor promptly if a fever lasts more than three days, if you keep vomiting, or if diarrhoea goes on for more than two days.
Get urgent help if you have chest pain or pressure, trouble breathing, black or bloody stools, or a sudden pounding headache. Chest tightness and a bad headache can both come from causes that need fast treatment.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Zhi Zi Chi Tang is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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