Educational information, not medical advice — ask your doctor or midwife.
Roselle is a tart red drink made from the dried flower cups of Hibiscus sabdariffa. In West Africa it is sold as sobolo, zobo or bissap. The Hausa name for the plant is yakuwa.
The part used is the calyx. That is the fleshy cup left behind when the flower drops. It tastes sharp, a bit like cranberry, and is drunk hot or cold.
The best studied use is mild hypertension (high blood pressure). Trials show a small drop in readings. Most of those trials were small and short.
Roselle has a long record of use in the region. Long use is not proof that something works, and it is not proof that it is safe. Both have to be checked on their own.
Nobody has pinned down how roselle lowers blood pressure, only that small trials show a modest drop.
In cell and animal studies, roselle extracts appear to relax blood vessels. They also seem to slow an enzyme called ACE. Some blood pressure drugs work on that same enzyme.
Whether this is what happens in a person drinking tea is not established. The amounts used in lab work are often far higher than a cup of sobolo.
In animal studies roselle acts as a mild diuretic (water pill). That means it makes the body pass more urine. This may add to the blood pressure effect, but it has not been shown clearly in people.
In test tubes the red pigments mop up free radicals. Lab antioxidant scores say little about what happens in the body. Treat them as a hint, not a result.
Roselle is mostly an ordinary drink, not a medicine in a bottle.
Common forms: - dried calyces sold loose, steeped hot or cold - home-brewed or street-sold sobolo, zobo and bissap - bottled and canned hibiscus drinks - teabags and instant powders - capsules, tablets and liquid extracts - jams, syrups, sauces and sweets
The leaves are also cooked as a vegetable in parts of West Africa. That is a food use, separate from the drink.
Sugar is the main thing to watch. Bottled and street versions are often very sweet. The unsweetened brew itself is low in calories.
Strength is not standard. A capsule of extract can be far stronger than a cup of tea. Labels rarely let you compare the two.
Roselle has been grown and drunk across West Africa for centuries. Households brewed the calyces into a cooling drink for gatherings, festivals and the breaking of fasts.
Healers in the region gave the drink for fevers, for swelling and to help people pass urine. The leaves were cooked as a relish or soup green. In Hausa the plant is called yakuwa.
Similar use is recorded well beyond West Africa. Sudan and Egypt know it as karkade. The Caribbean and Mexico drink it as sorrel and agua de jamaica.
Plant historians place its origin in Africa. Trade routes carried it to Asia and the Americas, where it became a local staple drink.
Stop drinking it and see a doctor if any of these happen:
- you feel dizzy, faint or unsteady when you stand up - your blood pressure readings fall below the target your doctor set - you get shakiness, sweating or confusion, which can mean low blood sugar - you have lasting stomach pain, vomiting or diarrhoea - your skin or the whites of your eyes turn yellow, or your urine turns dark
Get emergency help for swelling of the lips, tongue or throat, or trouble breathing. That can be a serious allergic reaction.
See your doctor before starting it if you take medicine for blood pressure, diabetes, malaria or mood.
In the United States, the UK and the EU, roselle is an ordinary food and drink ingredient. It is also sold as a herbal supplement. No medical claims are approved for it in those places.
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.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.
