Educational information, not medical advice — ask your doctor or midwife.
Roselle is a tart red drink made from the dried calyces of Hibiscus sabdariffa. The calyx is the fleshy cup that holds the flower. In West Africa the drink is sold as sobolo, zobo or zoborodo (Hausa).
People drink it cold as a refreshment and warm as a home remedy. The most common health claim is that it helps high blood pressure. It is also used as a mild diuretic, meaning a drink that makes you pass more urine.
Here is the honest verdict. Several small human trials show a modest drop in blood pressure, so this is one of the better-studied folk drinks. Long traditional use is not proof that it works, and it is not proof that it is safe.
The trials are short and small. Nothing shows that roselle prevents heart attacks or strokes. It is a drink, not a replacement for prescribed medicine.
The best-supported effect in people is a small fall in blood pressure in adults with mildly raised readings.
In test tubes and in animals, roselle extracts appear to relax blood vessels. They also seem to block ACE, the same target as some blood pressure drugs. Whether this is what happens in a person drinking a cup of sobolo is not settled.
In animal studies it acts as a mild diuretic. That may help the body shed some salt and water. This has not been measured well in human trials.
Roselle is rich in antioxidants in laboratory tests. Antioxidants mop up unstable molecules in cells. That lab finding has not been shown to change any disease outcome in people.
Lab work also hints at effects on fat and blood sugar handling. Human results for cholesterol and blood sugar are mixed and weak.
Dried calyces are the usual starting point for every form below.
Loose dried calyces, sold by weight in markets, brewed hot or cold.
Tea bags labelled hibiscus, roselle or sour tea.
Ready-to-drink sobolo or zobo, often sweetened and spiced with ginger, cloves, mint or pineapple.
Capsules, tablets and powders made from concentrated extract.
Jams, syrups, sauces and natural food colouring.
Strength differs hugely between forms. A home brew is far weaker than a capsule of concentrated extract. Street-sold drinks can carry a lot of added sugar, which matters if you have diabetes.
Roselle has been grown and drunk across West Africa for centuries. It likely came from West or Central Africa and spread widely through trade.
In Nigeria, Ghana, Senegal and Mali it was a daily household drink. Healers also gave it for fevers, for swelling and to help people pass urine.
Similar drinks grew up elsewhere. Egypt and Sudan have karkade, Mexico has agua de Jamaica, and the Caribbean has sorrel.
It was often served at weddings, naming ceremonies and during Ramadan. The drink sat somewhere between food and medicine in daily life.
Stop drinking it and see a doctor if any of the following happen.
You feel dizzy, faint or unsteady, or your home blood pressure readings drop unusually low.
Your skin or the whites of your eyes turn yellow, or your urine turns dark. These can be signs of liver trouble.
You get a rash, itching, swelling of the lips or face, or trouble breathing. Call emergency services for swelling or breathing trouble.
You have diabetes and your blood sugar runs low, with shaking, sweating or confusion.
You are taking it for high blood pressure and your readings stay high. High blood pressure usually has no symptoms, so it needs proper treatment and checks.
In the United States, the United Kingdom, the European Union and across West Africa, roselle is an ordinary food and drink ingredient. It is sold freely as tea, juice and food colouring.
Capsules and extracts are sold as supplements, not as approved medicines. No medicines regulator has approved it to treat high blood pressure or any other condition.
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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