Educational information, not medical advice — ask your doctor or midwife.
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Fu Hai Shi is pumice, a light rock full of gas bubbles. Chinese medicine uses it on its own as a mineral remedy. The name means "floating sea stone", because the rock floats on water.
In some Chinese markets, the same name is given to another material. It can mean the chalky skeleton of a sea creature (Costazia). So two very different things may arrive under one label.
In TCM it is used mostly for coughs with thick, sticky phlegm that is hard to bring up. It is also used for lumps and swellings. These include goitre (a swollen thyroid gland in the neck) and scrofula (swollen lymph glands in the neck).
It is also given for hot, difficult urination and for stones in the urinary tract.
The honest verdict on evidence is simple. No human trials of Fu Hai Shi have been published for any of these uses. Long use shows that people have trusted it for centuries; it does not show that it works.
That point holds for everything on this page. It is not repeated in the sections below.
No one has shown what Fu Hai Shi does in the human body. The ideas below come from tradition and from untested lab guesses. They are not proven mechanisms.
In TCM terms, Fu Hai Shi is salty in taste and cold in nature. It is said to clear heat from the lungs. It is also said to "transform" thick phlegm, so you can cough it up.
Tradition says it softens hard lumps and helps urine to flow.
One modern guess starts with silica, the mineral that makes up sand and glass. The rock is mostly silica, which does not dissolve well. So it may pass through the gut largely unchanged.
If that is right, very little would be taken up by the body. Any effect would have to come from trace minerals that do dissolve. This idea has not been tested in people.
Fu Hai Shi is sold as raw lumps, as crushed grains, and as a fine powder. The grains are used for decoction (a strong tea made by simmering). Sometimes it is calcined (heated very strongly), quenched, then ground.
It appears in classical multi-herb formulas far more often than it is taken alone.
Practitioners usually add it to a decoction. They simmer it longer than the plant parts, because rock gives up its soluble parts slowly.
Do not confuse the medicinal grade with the pumice stone sold for scrubbing feet. It is also not the pumice used in cleaning powders and concrete. Those are not prepared, tested or meant for swallowing.
Fu Hai Shi appears in Chinese medicine texts from about the Song dynasty onward. Later classics list it under the names Hai Fu Shi and Fu Shi. It was grouped with the phlegm-clearing minerals, next to Hai Ge Ke (clam shell).
Its classical reputation rests on two ideas. A stone light enough to float was thought to lift phlegm. A salty, cold mineral was thought to soften hard lumps in the neck.
It is still a recognised item in modern Chinese pharmacy practice, but a second-tier one. It is used far less often than the common phlegm herbs.
See a doctor promptly if you have a lump in your neck, a cough that lasts more than three weeks, coughing up blood, unexplained weight loss, night sweats, fever, or burning pain when you pass urine.
Go to an emergency department if you have severe pain in your side or back that comes in waves, cannot pass urine, have blood in your urine with fever, or have trouble breathing or swallowing.
Stop taking it and speak to a pharmacist or doctor if you get ongoing stomach pain, vomiting, or if a prescription medicine you take seems to have stopped working.
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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