Fu Hai Shi
Quick Facts
- What it is: Fu Hai Shi is pumice, a porous volcanic rock used in Traditional Chinese Medicine for thick phlegm, neck lumps and difficult urination.
- Main uses: Cough with thick, sticky phlegm, Goitre and swollen neck glands, Hot or difficult urination
- Best for: Traditional use within a practitioner-prescribed Chinese formula, not for self-treatment
- Active ingredients: Silicon dioxide (silica), Aluminium oxide, Trace iron, calcium, sodium, potassium and magnesium salts
- Forms: Crushed granules for decoction, Fine powder, Raw lumps, Component of multi-herb formulas
- Time to effect: Not known; no human studies have measured it.
- Side effects: Mainly stomach upset; the bigger concern is possible heavy metal content in untested mineral material.
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What is Fu Hai Shi?
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.
How does Fu Hai Shi work?
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.
What forms does Fu Hai Shi come in?
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.
Where it comes from:
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.
Who should avoid Fu Hai Shi?
- Do not use if you are pregnant or trying to become pregnant, because safety in pregnancy has never been tested and mineral medicines may carry lead or other heavy metals.
- Do not use if you are breastfeeding.
- Do not give it to children.
- Never swallow pumice sold as a bath or foot scrub, an abrasive, or a cleaning or building product.
- Do not use if you have weak digestion with long-term loose stools, poor appetite or a cold feeling in the belly, because this cold mineral is expected to make that worse.
- Do not use if your cough brings up thin, clear, watery phlegm rather than thick sticky phlegm.
- Do not use if you have reduced kidney function or kidney disease unless a doctor who knows your case agrees.
- Do not use if you are taking a tetracycline or quinolone antibiotic, levothyroxine for your thyroid, or a bisphosphonate for bone thinning, unless you can keep the doses at least four hours apart and your prescriber knows.
- Do not use it as a replacement for treatment of a diagnosed thyroid problem, a chest infection, tuberculosis or a urinary stone.
When should you see a doctor?
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.
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