Xi Gua Pi
Quick Facts
- What it is: Xi Gua Pi is dried watermelon rind, used in Traditional Chinese Medicine as a cooling herb for hot-weather thirst and mild fluid puffiness.
- Main uses: Heat discomfort and thirst in hot weather, Mild fluid puffiness, Scanty, dark urine
- Best for: Feeling overheated and thirsty in summer, as a traditional cooling drink
- Active ingredients: Citrulline (an amino acid), Potassium and other mineral salts, Pectin and soluble fibre, Lycopene and other carotenoids (plant pigments)
- Forms: Dried rind for decoction (simmered tea), Fresh rind, juiced or simmered, Powder or granules within a formula
- Time to effect: Cooling and thirst relief within minutes to an hour; nothing beyond that has been established.
- Side effects: Usually mild — loose stools, stomach chill, more frequent urination; potassium is the concern in kidney disease.
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What is Xi Gua Pi?
Xi Gua Pi is the pale green and white rind of the watermelon. It is dried and used as a single herb in Chinese medicine. It is classed as a cooling herb for "summerheat".
Summerheat is the old Chinese picture of hot weather illness. You feel hot, thirsty, sticky and tired. Urine is often scant and dark.
People take it as a mild cooling drink in hot spells. It is simmered into a decoction (a tea made by boiling the herb). It also goes into formulas for thirst, mouth sores and mild puffiness.
Here is the honest verdict on the evidence. Xi Gua Pi has a long, well noted place in Chinese herb books. But almost no modern human trials test the rind itself.
Long use and proof of effect are two different things. Here only the long use is strong.
How does Xi Gua Pi work?
Nobody has shown how Xi Gua Pi works in the body. The ideas below are proposals, not proven facts.
In Chinese medicine, the rind is sweet and cold. It is said to clear summerheat and to build fluids (ease dryness and thirst). It is also said to promote urination, which is why it is added to formulas for puffiness and hot, restless thirst.
In modern terms, the rind is mostly water, fibre and potassium. It also holds an amino acid called citrulline. Citrulline raises nitric oxide, a signal molecule that relaxes blood vessels.
That link was studied with strong citrulline pills and watermelon juice. It was not studied with dried rind at herb doses. So it does not tell you what a cup of rind tea will do.
What forms does Xi Gua Pi come in?
Xi Gua Pi is sold and used in a few simple forms.
- Dried rind slices or strips. This is the standard pharmacy form, simmered into a decoction (a tea made by boiling the herb). - Fresh rind, scraped free of the red flesh and the tough outer skin, then juiced or simmered at home.
- Powdered rind, sometimes added to granule formulas. - Pickled or candied rind as a food. This is a food use, not a medicine use.
Xi Gua Shuang (watermelon frost) is a different thing. It is made by curing watermelon with mirabilite. Treat it as a separate medicine, not as Xi Gua Pi.
Where it comes from:
Watermelon rind has been used in China for hundreds of years. It shows up in Qing dynasty herb books as a summerheat remedy. The best known example is the formula Qing Luo Yin.
It sits at the everyday, food-grade end of the Chinese herb cabinet. It is the kind of thing a family might brew at home in August. It is not saved for serious illness.
It is still a listed single herb in China today. Most often it plays a supporting part in a formula, not the lead.
Who should avoid Xi Gua Pi?
- Do not use if you have moderate or advanced kidney disease, because the rind is high in potassium and damaged kidneys cannot clear it.
- Do not use if you take lithium (a mood-stabilising medicine), because changes in urine output can push lithium in your blood to unsafe levels.
- Do not use if you take a potassium-sparing water pill such as spironolactone, amiloride or triamterene, unless your doctor has checked your potassium.
- Do not use if you have been told your blood potassium is high (hyperkalaemia).
- Do not use if you are allergic to watermelon.
- Do not use it to treat swelling of the ankles, legs or face that has not been explained by a doctor — swelling can come from the heart, kidneys or liver.
- Avoid it if you have ongoing watery diarrhoea, or a stomach that reacts badly to cold food and drink.
- Do not take medicinal-strength decoctions if you are pregnant or breastfeeding, unless a doctor or qualified practitioner agrees; eating watermelon as food is fine.
- Never use it in place of a prescribed water pill for heart failure or kidney disease.
When should you see a doctor?
See a doctor if swelling in your legs, ankles or face lasts more than a few days, gets worse, or comes with breathlessness.
Get medical help the same day if you have burning urine with fever, back pain or blood in the urine, or if you cannot keep fluids down in hot weather.
Go to an emergency department if you have muscle weakness with a slow or irregular heartbeat, or feel faint — these can be signs of a potassium problem.
Also check with your doctor or pharmacist before using Xi Gua Pi if you take any water pill, blood pressure medicine or lithium. Xi Gua Pi is a single herb, and single herbs still interact with prescription drugs.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
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