What is Cheng Liu?

Cheng Liu is the young twig and leaf of the tamarisk tree (Tamarix chinensis). It is used on its own as a single herb in Chinese medicine. Old texts gave it to help a measles rash come out fully, and to ease aches blamed on wind and damp.

In Chinese medicine it sits in the group of herbs that "release the outside". These are herbs thought to move a mild illness out through the skin by raising a light sweat. It is also boiled into a wash for itchy skin.

Here is the plain verdict. Cheng Liu has a long record in Chinese practice but almost no modern testing in people. A long history of use is not proof that a herb works, so this page grades the two things apart.

How does Cheng Liu work?

No one has shown how Cheng Liu works in the body. What follows is the old idea behind its use, plus a little lab work.

Chinese texts say the herb is acrid and warm. It was thought to open the pores and raise a light sweat, so a rash could surface and wind-damp could leave the joints.

Lab tests on tamarisk extracts show some antioxidant activity (they mop up unstable molecules) and some effect on inflammation in cells. That work was done in dishes and in animals, not in people. It does not tell you what a cup of the tea will do.

What forms does Cheng Liu come in?

Cheng Liu comes as dried twigs and leaves, cut small for boiling into a tea. This is the main form used in China.

You may also see it as a powder, or blended into a ready-made herb formula. A few shops sell a liquid extract.

The herb is also boiled and used as a skin wash or bath soak. Good material is grey-green and smells faintly of grass.

Where it comes from:

Cheng Liu appears in Chinese herb texts from around the 10th century, in the Song dynasty. It stayed in use through later Ming and Qing writing.

Its main job was always the same: help a slow measles rash in children come out. Country healers also used it for itchy skin and joint aches.

It is a known member of the Chinese herb list but a minor one. It is not used outside East Asian herb practice in any organised way.

What does Cheng Liu help with?

• Measles rash that is slow to come out (traditional use only): This is the classic use in Chinese texts. Healers gave a short course to help the spots surface, believing a stuck rash made a child sicker. There are no human trials testing this. Measles is a serious infection that needs a doctor, and a herb must never stand in for medical care or vaccination.
• Itchy skin rashes, used as a wash: The boiled twigs were used as a bath or wash for itch. Lab work shows some anti-inflammatory action in cells, but that is not the same as helping skin in people. No published human trial supports this use.
• Joint and muscle aches blamed on wind and damp: Old texts list Cheng Liu among herbs for aches that come and go with cold, damp weather. It was usually mixed with stronger herbs rather than used alone. There is no human evidence for pain relief.
• Early chills and fever from a common cold: Because it was thought to raise a light sweat, it was sometimes used in the first day or two of a cold. This is a traditional idea only. No trial has tested it against a dummy treatment.

Which foods are rich in Cheng Liu?

1. Tamarisk manna: a sweet, sticky drop that forms on some tamarisk trees and has been eaten in parts of the Middle East; it is not the same as the medicinal twig

What are the side effects of Cheng Liu?

• Sweating, which can leave you dry and thirsty
• Dizziness or feeling faint, more likely with large doses
• Nausea or vomiting with large doses
• Stomach upset when taken on an empty stomach
• Skin rash or itch from an allergy to the plant

Good to know:

Reported problems are mostly mild and tied to large doses. The honest limit is that no one has tracked side effects in a proper study, so the true rate is unknown.

The main risk is fluid loss from sweating. That matters most in small children, in older people, and in anyone already dry from fever or vomiting. Stop the herb and drink water if you feel dizzy or very thirsty.

How much Cheng Liu should you take?

• Recommended daily: No safe and useful dose has been set by research. What follows is the range named in Chinese herb texts, not a tested amount. Texts give about 3 to 10 grams of the dried herb, simmered in water and drunk over a day. Fresh herb is used at higher weights. For a skin wash, a larger amount is boiled and the cooled liquid is used on the skin only. The herb is meant to be given by a trained herbalist, usually inside a formula. Do not scale the dose up on your own.
• Best time of day: The tea is usually split into two doses, morning and evening. A skin wash is most often used at night, when itch tends to feel worse.
• With or without food: Take it after food with a little warm water. It is acrid and can upset an empty stomach.
• Time to effect: There is no tested answer. In traditional use it was judged within one to three days, and stopped if nothing changed.
• How long to take it: Tradition uses it for a few days, not for months. It was a short-course herb for an acute problem. If you are using it and nothing has changed in three days, stop and get medical advice. Any fever, rash or joint pain that lasts more than a few days needs a doctor, not a longer herb course.