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What Is Hibiscus Tea Good For? Benefits, Evidence and Risks

Hibiscus sabdariffa calyces (roselle, sour tea, karkade)

Hibiscus sabdariffa calyces (roselle, sour tea, karkade), the plant behind hibiscus tea
Photo: Invertzoo, CC BY-SA 4.0, via Wikimedia Commons

Hibiscus tea is best known for lowering blood pressure, and that is where the evidence is strongest: two to three cups a day dropped systolic pressure by about 7 mmHg in randomized trials. Its other main uses are nudging cholesterol in the right direction and helping with weight and metabolic syndrome, though those results are smaller and less consistent. It is also a tart, caffeine-free, zero-calorie drink that replaces soda or juice without sugar, which is a quiet benefit of its own.

The tea is made from the deep red calyces of Hibiscus sabdariffa, not the ornamental hibiscus in gardens. The colour comes from anthocyanins (delphinidin and cyanidin sambubiosides), and the sourness from hibiscus acid and citric acid. It also carries a useful dose of vitamin C, although hot brewing destroys some of it. Across West Africa, Egypt, Mexico and the Caribbean it has been a daily drink for centuries, served hot as karkade or cold as agua de jamaica.

Below, each claimed benefit is graded by the human evidence behind it, followed by how to brew it so it is not harsh, how much is sensible, and who should be careful. The short version: for most healthy adults, two to three cups a day is a good habit. If you take blood pressure medicine, hydroxychloroquine or regular acetaminophen, or you are pregnant, read the cautions first.

What hibiscus tea is good for

  • Blood pressure — 2 to 3 cups a day lowered systolic pressure by about 7 mmHg over 4 to 6 weeks in randomized trials
  • Cholesterol — some trials show lower LDL and higher HDL, others show no change; the evidence is mixed
  • Weight and metabolic syndrome — 12 weeks of hibiscus extract reduced body fat and waist size in one small trial
  • Blood sugar — modest fasting glucose improvements in metabolic syndrome; too early to count on
  • Uric acid — a small study found more uric acid passed in urine; people prone to kidney stones should check first
  • Antioxidants and vitamin C — anthocyanin-rich, caffeine-free and calorie-free when unsweetened

Hibiscus tea benefits, graded by the evidence

Strong = multiple human trials or a meta-analysis. Moderate = a few small trials. Preliminary = early, traditional or animal data.

  1. Lowers blood pressure

    Strong evidence

    In a Tufts University trial of 65 prehypertensive and mildly hypertensive adults, three 240 mL cups of hibiscus tea a day for six weeks lowered systolic pressure by 7.2 mmHg versus 1.3 mmHg on placebo, with the biggest drop (13.2 mmHg) in people who started highest. A 2015 meta-analysis of five randomized trials in 390 people found an average fall of 7.6 mmHg systolic and 3.5 mmHg diastolic. Earlier Mexican trials found 10 g of dried calyx a day performed about as well as captopril 50 mg over four weeks, and a little less well than lisinopril 10 mg.

    Key evidenceSerban et al., Journal of Hypertension 2015: meta-analysis of 5 RCTs, 390 participants.

  2. May improve cholesterol

    Moderate evidence

    Results are inconsistent. In 60 adults with type 2 diabetes, one month of sour tea twice daily raised HDL and lowered total cholesterol and LDL compared with black tea. A 2013 systematic review of lipid trials, however, found that only some showed meaningful changes and that trial quality was low. A reasonable summary is that hibiscus might trim LDL by a few points in people who start high, and it is unlikely to do much for people whose cholesterol is already normal.

    Key evidenceMozaffari-Khosravi et al., Journal of Alternative and Complementary Medicine 2009; Aziz et al., Journal of Ethnopharmacology 2013 (systematic review).

  3. Helps with weight and metabolic syndrome

    Preliminary evidence

    In a Taiwanese trial of 36 adults with a BMI of 27 or more, 450 mg of hibiscus extract three times a day for 12 weeks reduced body weight, body fat, waist-to-hip ratio and liver fat on ultrasound compared with placebo. A Mexican study gave 100 mg a day of a polyphenol extract to people with metabolic syndrome for one month and saw lower fasting glucose and total cholesterol and higher HDL. Both used concentrated extracts rather than tea, and both were small, so treat this as promising rather than proven.

    Key evidenceChang et al., Food and Function 2014 (12-week RCT, 36 adults).

  4. May lower blood sugar slightly

    Preliminary evidence

    Animal studies consistently show hibiscus lowers glucose, and the metabolic syndrome extract trial above found a drop in fasting glucose. But the one-month tea trial in people with type 2 diabetes did not find a significant change in blood sugar, and there is no trial showing a change in HbA1c from drinking the tea. If you have diabetes, it is a safe drink but not a treatment, and you should keep an eye on readings if you also take glucose-lowering medicine.

  5. Raises antioxidant status

    Preliminary evidence

    Hibiscus is rich in anthocyanins, protocatechuic acid and vitamin C. In eight healthy volunteers, a single 200 mL dose of hibiscus extract raised plasma antioxidant capacity and the urinary excretion of antioxidant metabolites for several hours. Whether a higher antioxidant reading translates into less disease is unproven for any food, so this is a mechanism, not an outcome.

    Key evidenceFrank et al., Journal of the Science of Food and Agriculture 2012 (8 healthy adults, crossover).

  6. Helps the body pass uric acid

    Preliminary evidence

    A Thai study gave nine healthy men and nine men with a history of kidney stones 1.5 g of dried hibiscus as tea twice daily for 15 days. Urinary uric acid excretion rose in both groups, with a small fall in serum uric acid. That is interesting for gout, but it is a single tiny study, and more uric acid in the urine is not helpful for people who form uric acid stones. Ask your doctor before using it for that purpose.

    Key evidencePrasongwatana et al., Journal of Ethnopharmacology 2008.

  7. Replaces sugary drinks without caffeine

    Moderate evidence

    This is the least exciting benefit and possibly the most useful. Unsweetened hibiscus has no calories, no caffeine and a strong enough flavour to stand in for soda, juice or sweet iced tea. Swapping one 12 oz sugary drink a day removes roughly 140 kcal and 35 g of sugar, and large cohort studies link each daily sugar-sweetened drink to higher weight and diabetes risk. Hibiscus cold-brewed with a little lime is the easiest swap most people stick with.

Is hibiscus tea good for you?

  • Yes, for most adults: two to three cups a day is safe, caffeine-free, calorie-free unsweetened, and the only herbal tea with consistent trial evidence for lowering blood pressure.
  • Expect a modest blood pressure drop of about 5 to 10 mmHg systolic if you start high, little change if you are already normal, and nothing dramatic for cholesterol, weight or blood sugar.
  • Limit or avoid it if you take blood pressure medicine (your pressure can go too low), hydroxychloroquine or chloroquine (hibiscus cuts their absorption), or regular acetaminophen.
  • Skip it in pregnancy and if you are trying to conceive, since animal studies show effects on the uterus and hormones and there are no human safety data.
  • It is acidic enough to wear tooth enamel over time, so drink it with meals, rinse with water afterwards, and do not sip it slowly all day.

How to brew hibiscus tea

Amount

1 to 2 teaspoons (2 to 4 g) dried calyces, or 1 bag, per 8 oz (240 mL)

Water

Just boiled, 200 to 212°F / 93 to 100°C for hot tea; cold water for cold brew

Steep

5 to 10 minutes hot; 8 to 12 hours in the fridge for cold brew

  • Cold-brewing (1 tablespoon per litre overnight) gives a smoother, less astringent cup and preserves more vitamin C.
  • If it is too sour, add a cinnamon stick, a slice of ginger or a little orange peel rather than sugar.
  • The trials used about 1.25 g of dried calyx per 240 mL, so a standard tea bag and a short steep is enough; stronger is not better.

How much per day

Two to three 8 oz cups a day matches the doses that lowered blood pressure in trials. There is no good reason to go above four cups, and the acidity makes more than that hard on teeth and the stomach.

Caffeine-free. Safe in the evening and for people cutting back on coffee.

Side effects, interactions and who should limit it

Side effects

  • Tooth enamel erosion with heavy, frequent sipping, because the tea is as acidic as orange juice (pH around 2.5 to 3).
  • Light-headedness or fatigue if your blood pressure drops too far, especially alongside antihypertensive drugs.
  • Heartburn or an upset stomach in people with reflux or gastritis, due to the acidity.
  • Mild diuretic effect: more trips to the bathroom in the first few days.
  • Very high doses of extract caused liver stress in rats; there are no reports at tea doses, but there is no reason to take concentrated extracts long-term without a doctor.

Interactions

  • Antihypertensives (ACE inhibitors, ARBs, calcium channel blockers, diuretics): additive blood pressure lowering; check readings if you combine them.
  • Chloroquine and hydroxychloroquine: hibiscus drink reduced chloroquine absorption substantially in a human study; do not take them together.
  • Acetaminophen (paracetamol): hibiscus water sped up its elimination in a small human study, which could blunt its effect.
  • Hydrochlorothiazide: a human study found hibiscus altered the drug's absorption and elimination; separate doses by several hours.
  • Simvastatin and diclofenac: small human studies found hibiscus changed their blood levels; ask a pharmacist before daily use.
  • Diabetes medicines: a theoretical additive glucose-lowering effect; monitor if you drink a lot.

Pregnancy and breastfeeding

Avoid hibiscus tea in pregnancy and while trying to conceive. Animal studies show it can affect oestrogen levels, delay puberty in offspring and stimulate the uterus, and there are no human safety studies. Data in breastfeeding are also lacking, so an occasional cup is a judgement call and daily use is better skipped.

Frequently asked questions

Does hibiscus tea really lower blood pressure?

Yes, modestly. Across five randomized trials, drinking it daily for four to six weeks lowered systolic pressure by about 7 to 8 mmHg and diastolic by 3 to 4 mmHg. That is similar to cutting salt hard or losing 5 kg, and smaller than most single drugs. It works best in people whose pressure is mildly raised and does little for people already in the normal range.

What are the benefits of hibiscus tea for women?

The benefits are the same as for men: blood pressure, a possible lift in HDL, and a sugar-free, caffeine-free drink. There is no good evidence it balances hormones or helps with menstrual cramps, despite claims online. Women should know that animal data suggest it can affect oestrogen and the uterus, so it is best avoided in pregnancy and when trying to conceive.

Is it safe to drink hibiscus tea every day?

For healthy adults, yes. The trials ran six weeks at two to three cups a day without serious side effects. The main daily-use concerns are tooth enamel from the acidity and the drug interactions listed above. If you take blood pressure medicine, tell your doctor so your dose can be checked.

Does hibiscus tea help you lose weight?

A little, possibly. One 12-week trial of hibiscus extract in overweight adults found small reductions in weight, body fat and waist size. The tea itself has not been tested for weight loss. The most reliable effect is indirect: if it replaces a daily sugary drink, that alone removes roughly 140 calories a day.

Is hibiscus tea good for the liver and kidneys?

The extract reduced liver fat in one small trial, and a tiny study found it helped the kidneys pass uric acid. Both are preliminary. At very high extract doses, animal studies showed liver and kidney stress, so stick to the tea rather than concentrated capsules, and check with your doctor if you have kidney disease or a history of stones.

Does hibiscus tea have caffeine?

No. Pure hibiscus is caffeine-free, which is why it is a good evening drink and a safe swap for people cutting back on coffee. Check blends, though: some fruit teas mix hibiscus with black or green tea.

References

  1. McKay DL, Chen CY, Saltzman E, Blumberg JB. Hibiscus sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adults. Journal of Nutrition (2010)View source
  2. Serban C, Sahebkar A, Ursoniu S, Andrica F, Banach M. Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension: a systematic review and meta-analysis of randomized controlled trials. Journal of Hypertension (2015)View source
  3. Herrera-Arellano A, Flores-Romero S, Chávez-Soto MA, Tortoriello J. Effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa in patients with mild to moderate hypertension: a controlled and randomized clinical trial. Phytomedicine (2004)
  4. Herrera-Arellano A, Miranda-Sánchez J, Avila-Castro P, et al.. Clinical effects produced by a standardized herbal medicinal product of Hibiscus sabdariffa on patients with hypertension. A randomized, double-blind, lisinopril-controlled clinical trial. Planta Medica (2007)
  5. Mozaffari-Khosravi H, Jalali-Khanabadi BA, Afkhami-Ardekani M, Fatehi F. Effects of sour tea (Hibiscus sabdariffa) on lipid profile and lipoproteins in patients with type II diabetes. Journal of Alternative and Complementary Medicine (2009)
  6. Aziz Z, Wong SY, Chong NJ. The effects of Hibiscus sabdariffa on blood pressure and lipids: a systematic review. Journal of Ethnopharmacology (2013)
  7. Chang HC, Peng CH, Yeh DM, Kao ES, Wang CJ. Hibiscus sabdariffa extract inhibits obesity and fat accumulation, and improves liver steatosis in humans. Food and Function (2014)
  8. Prasongwatana V, Woottisin S, Sriboonlue P, Kukongviriyapan V. Uricosuric effect of Roselle (Hibiscus sabdariffa) in normal and renal-stone former subjects. Journal of Ethnopharmacology (2008)
  9. Mahmoud BM, Ali HM, Homeida MM, Bennett JL. Significant reduction in chloroquine bioavailability following coadministration with the Sudanese beverages Aradaib, Karkadi and Lemon. Journal of Antimicrobial Chemotherapy (1994)
  10. Frank T, Netzel G, Kammerer DR, et al.. Consumption of Hibiscus sabdariffa L. aqueous extract and its impact on systemic antioxidant potential in healthy subjects. Journal of the Science of Food and Agriculture (2012)

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This page is educational and is not medical advice. Herbal teas can interact with prescription medicines. Talk with a clinician or pharmacist before relying on any of them, especially if you are pregnant, breastfeeding, have a chronic condition, or take medication.