Educational information, not medical advice — ask your doctor or midwife.
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Zeng Ye Tang is a Chinese herb formula made from three herbs. It is sold as one product, not as three separate herbs. People take it for dry, hard stools and for a dry mouth and throat.
Its English name is Increase the Fluids Decoction. It suits people who look dry, rather than "hot" or blocked up.
The three herbs are raw Rehmannia (Sheng Di Huang), Ophiopogon root (Mai Men Dong) and Scrophularia root (Xuan Shen). In Chinese medicine, these herbs are said to "moisten" the body. They are said to bring back body fluids.
Here is the evidence in one line. Its standing in tradition is strong and goes back a long way. But human trial evidence is thin, and we found no well-reported trial we trust.
Long use in a tradition is not proof that something works. That point applies to everything on this page.
No one has shown clearly how this formula works in the body. So treat any account of how it works as a theory, not a fact.
In traditional terms, it is said to "increase the fluids to float the boat". The idea is that a dry gut cannot move stool along. So you add moisture, rather than force the bowel with a purgative (a strong laxative).
In lab terms, the likely story is much plainer. Rehmannia and Ophiopogon hold a lot of sugars and mucilage. Mucilage is a slimy plant carbohydrate that holds water.
That water can stay in the gut and soften stool. Lab and animal studies also report effects on saliva (spit) and on inflammation (swelling). But animal results often do not carry over to people.
This is not a stimulant laxative. It is not thought to work by irritating the bowel wall. It should not cause cramps the way senna or bisacodyl can.
You will usually meet it in one of these forms:
Raw herbs for a decoction. You simmer the three dried roots in water at home and drink the liquid as a tea. This is the classical form.
Concentrated granules. This is a powder or granule made from a water extract, which you stir into hot water. It is the most common modern form.
Pills or tablets, often called "teapills". They are handy, but each dose is usually weaker.
Liquid extracts made by a practitioner. These are sometimes adjusted with extra herbs to suit one person.
The formula comes from a book called Wen Bing Tiao Bian. The English title is Systematic Differentiation of Warm Diseases. Wu Ju-tong wrote it in 1798.
It was made for the dryness left behind after a feverish illness. In that state the tongue is dry and red, and the stool will not pass.
It became a standard teaching formula. Chinese medicine schools still teach it today.
It is a staple of one tradition: Chinese herbal medicine. Many cultures did not take it up on their own.
Stop taking it and see a doctor if your constipation has not improved after two weeks, or if it keeps coming back.
Get medical advice promptly if you notice blood in your stool, unexplained weight loss, black or tarry stools, or a lasting change in your usual bowel pattern.
Get urgent care the same day for severe belly pain with vomiting and no wind or stool passing, or if you bruise or bleed easily while taking this alongside a blood thinner.
Call emergency services for swelling of the face, lips or tongue, a spreading rash, or trouble breathing.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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