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Hibiscus tea is a tart, deep red herbal tea brewed from the dried calyces of the roselle plant, Hibiscus sabdariffa. The hibiscus tea benefits people search for most involve blood pressure: a small US trial and a 2015 meta-analysis reported modest drops, but a 2021 Cochrane review found the evidence too weak to draw conclusions for people with high blood pressure. Here is what hibiscus tea contains, what the research shows, which medicines may interact with it and what to check on supplement labels.
Peptide Labs sells two capsule supplements whose labels list hibiscus, described below; this article does not recommend them and is general information, not medical advice.
Key Takeaways
- Hibiscus tea is made from the calyces of Hibiscus sabdariffa, also called roselle, sour tea or red tea.
- A 6-week US trial found a modest drop in systolic blood pressure in adults with mildly raised readings.
- A 2021 Cochrane review judged the evidence insufficient for people with diagnosed high blood pressure.
- Studies suggest hibiscus may interact with hydrochlorothiazide, chloroquine and acetaminophen.
- Hibiscus tea is not a substitute for blood pressure medicine; talk to your doctor before combining them.
What is hibiscus tea?
The roselle plant is a tropical relative of the ornamental hibiscus. After it flowers, the fleshy red cup around the seed pod, called the calyx, is dried and steeped in hot or cold water. The drink goes by many names: roselle, sour tea or red tea in English, karkadi in Sudan and zobo in Nigeria, where it is often sweetened.
According to the LactMed database at the National Library of Medicine, hibiscus flowers contain anthocyanins, proanthocyanidins and flavonols, plant pigments in the polyphenol family, along with organic acids that give the tea its sour taste. LactMed also notes that hibiscus is generally recognized as safe (GRAS) by the FDA as a food. That status covers its use in foods and drinks; it does not mean concentrated extracts have been tested for every use or every person.
Hibiscus tea benefits: what the research shows
Most human research on Hibiscus sabdariffa looks at blood pressure, and the results depend on which studies a reviewer includes. The summaries below describe research findings; they do not show that hibiscus tea can manage a medical condition, and they are not a reason to change any prescribed medicine. If you have high blood pressure, work with your doctor on a plan.
| Study | Who was studied | What it found | Main limitation |
|---|---|---|---|
| McKay et al. 2010 (Tufts) | 65 adults with prehypertension or mild hypertension, no BP medicines | Systolic pressure fell 7.2 points vs 1.3 with placebo over 6 weeks | Small and short |
| Serban et al. 2015 meta-analysis | 5 trials, 390 people | Average drops of about 7.6 systolic and 3.5 diastolic points | Few trials; more needed |
| Cochrane review 2021 | 1 eligible trial, 60 people with type 2 diabetes | Evidence insufficient to judge any effect | Very low certainty |
Hibiscus tea and blood pressure
The most cited study came from the USDA Human Nutrition Research Center on Aging at Tufts University. In this randomized, double-blind trial, 65 adults aged 30 to 70 with prehypertension or mild hypertension, none taking blood pressure medicine, drank brewed hibiscus tea or a placebo drink for six weeks. Systolic pressure, the top number, fell more with hibiscus (7.2 points versus 1.3). Diastolic pressure did not differ significantly from placebo, and people with higher starting readings tended to respond more.
A 2015 meta-analysis in the Journal of Hypertension pooled five randomized trials with 390 participants and reported average reductions of about 7.6 points systolic and 3.5 points diastolic. The authors called for further well-designed trials. A 2021 Cochrane review applied stricter entry rules, looking only at placebo-controlled trials in adults with primary hypertension, and found just one study that qualified, in 60 people with type 2 diabetes who took hibiscus extract capsules. Its conclusion: the evidence is insufficient to say whether roselle lowers blood pressure in people with hypertension, and the certainty is very low.
Put together, hibiscus tea blood pressure research shows a possible modest effect in small, short studies, but no long-term trials of heart attacks or strokes. Our guide to hawthorn berry covers another botanical studied for the heart, with similar cautions about heart medicines.
Other claims
Hibiscus is also marketed for cholesterol, blood sugar, weight and liver health, and as a breast milk booster. Evidence for these uses is limited. LactMed states plainly that no scientifically valid clinical trials support hibiscus for increasing milk supply. Because hibiscus has been studied for increasing urine output, it also appears in diuretic-themed products; our guides to dandelion root and water pills explain what over-the-counter diuretic products can and cannot do.
Hibiscus tea side effects and medicine interactions
As a food drink, hibiscus tea is widely consumed and generally well tolerated, according to LactMed. Hibiscus tea side effects and interaction concerns come mainly from small studies, so the size of the risk for any one person is unclear. These points matter most:
- Blood pressure medicines: if hibiscus lowers blood pressure even modestly, combining it with prescribed medicine could add to the effect. Tell your doctor if you drink hibiscus tea regularly, and do not stop or reduce a prescribed medicine on your own.
- Hydrochlorothiazide: in a 2011 study in rats and rabbits, hibiscus extract given with this common diuretic increased urine output and raised and prolonged blood levels of the drug. Animal results do not always apply to people, but they are a reason to ask your prescriber.
- Chloroquine: in a 1994 study in healthy men in Sudan, taking this antimalarial drug with karkadi (hibiscus) drink sharply reduced the amount of drug absorbed compared with water.
- Acetaminophen: a 2004 study in six healthy men found that zobo drink before acetaminophen did not change its absorption but sped its removal from the body. The clinical meaning is unknown.
- Allergy: LactMed notes possible allergic reactions, including cross-reactions with other plants in the mallow family such as marshmallow.
- Pregnancy and breastfeeding: safety in pregnancy has not been established in human studies, and LactMed reports no data on hibiscus in breast milk or in nursing infants. Ask your clinician before using hibiscus products.
Pharmacists can check interactions quickly, so bring the tea or supplement label to your next visit. If you take several medicines, the timing and the combination matter more than any single cup.
Hibiscus tea vs hibiscus supplements
A cup of brewed tea and a capsule are different products. Tea strength varies with the amount of calyces, the water temperature and the steeping time, and many bottled hibiscus drinks add sugar. Supplements usually contain an extract or powdered flower, often blended with other ingredients, so studies of the tea do not tell you what a particular capsule will do.
Two products we carry list hibiscus as an active ingredient. Bragg Metabolism Natural GLP-1 Support combines Bragg organic apple cider vinegar with Metabolaid, a trademarked blend of lemon verbena leaf extract and hibiscus flower extract; its label advises asking a healthcare professional before use if you are pregnant or nursing, take medication or have a medical condition (more from the Bragg brand page). Etta Vita GLP-1 Support Supplement lists hibiscus flower powder among 11 ingredients, including berberine, green tea extract and probiotic cultures, and its label says the berberine must be taken with food. Neither is a GLP-1 medication; our guide to GLP-1 support supplements explains what that label term means.
- Read the full ingredient list: blends can contain berberine, caffeine or other herbs with their own interaction profiles.
- Check for proprietary blends: some labels list a blend total rather than the amount of hibiscus itself.
- Look for testing: see our guide to third-party tested supplements for what the major seals verify.
If you enjoy a tart drink, our lemon water guide covers another popular option and how acidic drinks affect teeth.
Frequently Asked Questions
What are the main hibiscus tea benefits?
Hibiscus tea is a flavorful, caffeine-free herbal drink rich in plant pigments. Small trials reported modest blood pressure drops, but a 2021 Cochrane review found the evidence insufficient for people with hypertension.
Does hibiscus tea lower blood pressure?
A 6-week trial in adults with mildly raised readings found a modest systolic drop, and a 2015 meta-analysis agreed. Better trials are needed, and the tea does not replace medicine your doctor prescribes.
What are hibiscus tea side effects?
It is generally well tolerated as a drink. Allergic reactions are possible, and studies suggest interactions with hydrochlorothiazide, chloroquine and acetaminophen.
Can I drink hibiscus tea with blood pressure medicine?
Ask your doctor or pharmacist first. Hibiscus may add to the effect of blood pressure medicines, and an animal study found it raised blood levels of hydrochlorothiazide.
Is hibiscus tea safe during pregnancy?
Safety in pregnancy has not been established in human studies, and there are no data on breastfeeding. Talk to your clinician before using hibiscus tea or supplements.
What is Hibiscus sabdariffa?
It is the roselle plant. Its dried red calyces are used for hibiscus tea, known as karkadi in Sudan and zobo in Nigeria.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines or are pregnant. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
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