Hibiscus (Hibiscus sabdariffa)

The deep red calyx of the roselle plant, sold as 'sour tea' in much of the world and as agua de jamaica in Latin America. Tart, refreshing, and one of the few culinary herbs with solid evidence for lowering blood pressure.

Modestly lowers blood pressure with daily use — comparable in effect to some prescription starting doses in mild hypertension
Modestly lowers LDL cholesterol
Rich in the deep red antioxidant pigments found in dark berries
May support liver function and metabolic health
Mild diuretic action
Pleasant tart flavor makes daily use easy — usually consumed as cold or hot tea

Use caution with blood pressure medications — additive lowering effect

Use caution with diuretics — additive water-loss effect

May reduce the effectiveness of acetaminophen by speeding its clearance from the body

May lower blood sugar — caution with diabetes medication

Skip during pregnancy — can stimulate the uterus

Research

A Comparative Study of Iron Bioaccessibility and Antinutrient Levels in Hibiscus sabdariffa (Roselle) Leaves and Calyces and Persea americana (Avocado) Leaves and Seeds: Nutritional Implications.
Isingoma BE, Christine Mugumya K, Edward B · Journal of the American Nutrition Association · 2026
Fabrication of pH-Sensitive Bacterial Cellulose Films by Acetic Acid Fermentation of Anthocyanin-Rich Roselle (Hibiscus sabdariffa L.) Extracts for Real-Time Monitoring of Chicken Meat Spoilage.
Nguyen TV, Nguyen DT, Tran TTV · Journal of food science · 2026
Comparison of Hibiscus sabdariffa L. extract and hydrochlorothiazide as adjuncts to Valsartan in managing hypertension in type 2 diabetic nephropathy: A randomized clinical trial.
Kiani M, Mirzaei H, Enayati A · Avicenna journal of phytomedicine · 2026

Memorial Sloan Kettering About Herbs · EMA Herbal Medicinal Product Monographs · American Botanical Council HerbMedPro · Memorial Sloan Kettering About Herbs · EMA Herbal Medicinal Product Monographs · American Botanical Council HerbMedPro

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Common questions

There's real evidence for it. Daily hibiscus tea has been shown to modestly lower blood pressure, with effects in some studies comparable to a low starting dose of a prescription medication. It works best as a daily habit over weeks, not a one-time fix. Memorial Sloan Kettering

Talk to your provider first. Hibiscus can add to the blood-pressure-lowering effect of medication, and combined with a diuretic it can also increase water loss. Neither is dangerous on its own, but your provider may want to adjust dosing.

Most guidance says to skip it. Hibiscus has traditionally been used to stimulate the uterus, so it's generally not recommended during pregnancy.

It can. Hibiscus may speed up how quickly the body clears acetaminophen, which could make a dose less effective. If you take Tylenol regularly, mention your hibiscus tea habit to your provider.