Educational information, not medical advice — ask your doctor or midwife.
Lei Wan is a dried fungus body that grows under the ground. Chinese medicine uses it to clear worms from the gut. Tapeworm is the main target.
It is a single herb, not a blend. Another name for it is Omphalia sclerotium, or thunder ball fungus. In classic practice it is ground to a powder and swallowed, never boiled.
The evidence in one line: it has been used in China for a very long time. There are some old hospital case reports. But we can point to no good modern human trials.
Long use tells you that a remedy has been valued for many years. It does not prove the remedy works.
Worm infections are found with a stool test. Modern prescription drugs treat them very well. Treat Lei Wan as a traditional option to talk over with a doctor, not as a swap for that testing and treatment.
Lei Wan holds a protease. That is an enzyme that breaks down protein.
The main idea is that this enzyme harms the body wall of a tapeworm in the gut. The worm then loses its grip. It is passed out in the stool.
The enzyme is fragile. Heat and stomach acid break it down. That is why the herb is taken as a raw powder, not boiled into a tea.
This idea comes from lab work on worms in dishes. It also comes from what healers saw over the years. Modern controlled studies in people have not confirmed it, so treat it as a fair guess, not a settled fact.
Lei Wan is nearly always used as a fine raw powder. It comes loose or packed into capsules. This matters, because the old rule is clear: it must not be cooked.
Common forms you may meet: - Loose powder, stirred into cool or lukewarm water - Capsules of plain powdered herb - Ready-made pills that mix it with other herbs, such as Bing Lang (areca seed) or Nan Gua Zi (pumpkin seed)
Some shops sell it as a herb to be simmered in a decoction (a boiled herb tea). That goes against traditional use. It is not likely to do what the label claims.
Lei Wan shows up in the Shen Nong Ben Cao Jing (Divine Farmer's Classic of Materia Medica). That book was put together around the second century CE. The herb has stayed in Chinese medicine ever since.
It has one job in that tradition. It kills and expels parasites (worms and other pests that live in the body). The main target is tapeworm, and sometimes hookworm or roundworm.
Later texts warn that it should be powdered and taken cold. It should not be boiled.
In 20th-century China, hospitals used it in worm clearing programmes. That was before modern anti-worm drugs were easy to get. It is a staple of one tradition, not a remedy shared across many.
See a doctor before you start, so the worm can be identified from a stool sample and treated properly.
Get medical help quickly if you have severe belly pain, blood in your stool, a fever, repeated vomiting, or yellowing of your skin or eyes (a sign of liver trouble).
Go to emergency care straight away if you have a seizure (a fit), sudden confusion, or new changes in your vision. Pork tapeworm larvae can lodge in the brain, and that is a medical emergency, not something to treat with herbs.
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 Lei Wan 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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