Fu Ping
Quick Facts
- What it is: Fu Ping is dried duckweed, a floating water plant used in Chinese herbal medicine to promote sweating, vent rashes and increase urine flow.
- Main uses: Fever with no sweating in an early cold, Itchy rashes and hives, Helping a measles rash surface, Swelling with scanty urine
- Best for: Short-term use inside a prescribed Chinese formula for a wind-heat pattern
- Active ingredients: Flavonoids (orientin, vitexin, luteolin glycosides), Potassium salts, Carotenoids, Polysaccharides (large plant sugars)
- Forms: Dried herb for decoction (a tea boiled from herbs), Powder, Granules and pills within formulas, Cooled decoction used as a skin wash
- Time to effect: Sweating within hours by tradition; no reliable figure exists for any other use.
- Side effects: Mostly sweating, extra urine and the dryness or dizziness that follows; poorly sourced material may carry heavy metals.
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What is Fu Ping?
Fu Ping is the dried whole plant of duckweed (Spirodela polyrhiza), a tiny green plant that floats on ponds. In Chinese herbal medicine it is used to make you sweat, to help a skin rash come out, to calm itching, and to move extra fluid out of the body as urine.
Here is the short verdict. Fu Ping has a long, well-documented place in Chinese materia medica, but we could find no human trials of it, so its effects in people are unproven. A long history of use is not proof that something works, and that gap applies to everything below.
Fu Ping is a single drug (single herb), not a mixture. In practice it is almost always used as one ingredient inside a larger prescribed formula rather than on its own.
How does Fu Ping work?
Traditional theory says Fu Ping is pungent and cold. It is said to open the pores so heat can leave the body through sweat, push a rash to the surface, and drain water downward through urine.
In modern terms, laboratory and animal work points to flavonoids (plant pigments with antioxidant activity) and to potassium salts that may act as a mild diuretic (something that makes you pass more urine). None of this has been confirmed in people, so treat it as a possible explanation, not a proven one.
What forms does Fu Ping come in?
Fu Ping comes in a small number of forms:
Dried whole herb, simmered in water to make a decoction (a strong tea boiled from herbs). This is the standard form.
Ground powder, taken mixed with warm water.
Pills and granules, usually as part of a multi-herb formula.
A strong decoction used cooled as a skin wash or bath additive for itching.
Fresh duckweed is used in some regions but is harder to source safely.
Where it comes from:
Duckweed appears in the Shen Nong Ben Cao Jing, a Chinese materia medica compiled around the first to second century CE, under the name Shui Ping. Later texts settled on Fu Ping.
Classical doctors used it for fevers with no sweating, for measles rash that was slow to appear, for itchy skin eruptions, and for swelling with scanty urine. It has stayed in Chinese pharmacopoeias ever since, though it has always been a supporting herb rather than a headline one.
Who should avoid Fu Ping?
- Do not use if you are pregnant or trying to become pregnant, as Chinese texts warn against sweating and fluid-draining herbs in pregnancy and no safety data exists
- Do not use if you are breastfeeding, because nothing is known about what passes into breast milk
- Do not use if you already sweat heavily, sweat at night, or feel weak and drained, as this herb is meant to increase sweating
- Do not use if you are dehydrated (short of body water), have been vomiting, or have had diarrhoea
- Do not use if you take lithium, unless your prescriber agrees and monitors your blood levels
- Do not use if you take water tablets (diuretics) or blood pressure medicines, without asking your doctor first
- Do not use if you have kidney disease, heart failure or liver disease, all of which change how your body handles fluid
- Do not use if you have low potassium (a mineral your heart and muscles need) or any known heart-rhythm problem
- Do not use if you cannot confirm the supplier tests for heavy metals, because duckweed absorbs lead and cadmium from the water it grows in
- Do not use if you have ever reacted badly to duckweed or to a formula containing Fu Ping
- Do not give it to a child, or take it yourself, in place of medical care for measles or a high fever
- Do not harvest duckweed from a pond, ditch or waterway to use yourself
When should you see a doctor?
See a doctor rather than reaching for this herb if you have a fever above 39C, a fever lasting more than three days, or a fever with a stiff neck, confusion or a severe headache.
Get medical help the same day for a rash that spreads fast, blisters, or comes with facial swelling, wheezing or trouble breathing. Get urgent help for swelling of the legs or face that appears suddenly, for breathlessness lying flat, or for a big drop in how much you are passing urine.
Stop taking it and speak to a doctor if you feel faint, very thirsty, weak or dizzy on standing, or if your heart feels like it is racing or skipping.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
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