Hibiscus sabdariffa (roselle, sour tea) is a tropical plant whose flower parts are made into a tart tea or extract, used mainly for blood pressure. A 2022 meta-analysis found lower systolic blood pressure, but a Cochrane review found the evidence in people with high blood pressure too weak to judge.
Also known as: Hibiscus sabdariffa, roselle, sour tea, hibiscus tea.
Trials used teas and extracts of different strengths. The one trial in the Cochrane review gave roselle extract capsules (5,600 mg in total) for 8 weeks (Pattanittum 2021). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
What studies show: a 2022 meta-analysis of 17 trials found hibiscus lowered systolic blood pressure by about 7 mmHg more than placebo, more in people who started with higher blood pressure, and lowered LDL cholesterol by about 7 mg/dL compared with other teas and placebo; results varied widely between trials (Ellis 2022). The 2021 Cochrane review, which used stricter criteria, found only 1 eligible trial (60 people with type 2 diabetes) and concluded the evidence is insufficient to say whether roselle lowers blood pressure in people with hypertension (Pattanittum 2021).
Safety: the Cochrane review notes that its one trial did not report withdrawals due to side effects. The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for hibiscus that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
How Dose Track handles peptides · Reconstitution calculator · Half-life calculator