Index of Herbs

Evidence review

Hibiscus for Blood Pressure

Hibiscus sabdariffa

The short answer

Promising clinical evidence

Probably a little, in people whose blood pressure is mildly raised. In short trials, hibiscus tea or extract lowered systolic pressure by about 7 mmHg more than placebo or comparison drinks on average, but the studies are small and inconsistent, and Cochrane judged the evidence insufficient. Hibiscus may add to the effect of blood pressure drugs and is not a replacement for them.

7 key studies reviewed

Updated October 12, 2026

Key points

  1. 01

    A small drop, mainly systolic

    Pooled trials put systolic pressure about 7 mmHg lower than placebo, other teas, or diet, most in people with higher readings. Effects on diastolic pressure are less consistent.

  2. 02

    One careful placebo trial

    In 65 US adults not on medication, three cups a day for six weeks cut systolic pressure 7.2 mmHg versus 1.3 mmHg on a placebo drink. A tea company co-funded it.

  3. 03

    Cochrane is not convinced

    Cochrane’s 2021 review found only one eligible placebo-controlled trial in people with hypertension, with no clear effect and very low certainty evidence.

  4. 04

    Not a substitute for medicine

    Short trials found hibiscus similar to captopril but weaker than lisinopril and ramipril. No trial has measured whether it prevents strokes or heart attacks.

  5. 05

    Check interactions and readings

    Hibiscus may add to blood pressure drugs, and in small studies it cut simvastatin and chloroquine levels. Avoid medicinal amounts in pregnancy.

Hibiscus tea probably lowers blood pressure a little in people whose readings are mildly raised, but the evidence is not strong enough to treat high blood pressure with it. In the best-known placebo-controlled trial, three cups a day for six weeks lowered systolic pressure (the top number) by 7.2 mmHg, against 1.3 mmHg with a look-alike placebo drink (McKay and colleagues, Journal of Nutrition 2010). Pooled analyses of up to 17 trials find an average systolic drop of about 7 mmHg compared with placebo, other teas, or diet, with large differences between studies. Cochrane, which accepts only trials against placebo or no treatment in people diagnosed with hypertension, found a single eligible trial and judged the evidence insufficient. No trial has tested whether hibiscus prevents strokes or heart attacks, and it can interact with several medicines. That makes it promising rather than proven: at most a modest addition to diet and lifestyle changes, agreed with a clinician, not a treatment in its own right.

High blood pressure (hypertension) affects almost half of US adults, according to the US National Center for Complementary and Integrative Health (NCCIH), and over time it can damage the heart, blood vessels, and kidneys, leading to heart attacks, heart failure, stroke, and chronic kidney disease. It is managed with lifestyle changes and, when those are not enough, with medicines. The hibiscus used for tea is roselle, Hibiscus sabdariffa, whose fleshy red calyces make the tart drink known as bissap in Senegal, karkadé in Sudan and Egypt, zobo in Nigeria, agua de Jamaica in Mexico, and sorrel in the Caribbean. Cochrane notes that it is drunk both to quench thirst and as a medicine. Trial authors in Nigeria and Senegal describe its popular use for high blood pressure, and Mexican researchers note its use as an antihypertensive in several countries. Animal experiments reported blood pressure lowering, and pharmacological work pointed to a mild diuretic action and inhibition of angiotensin-converting enzyme (ACE), the target of drugs such as lisinopril, which led to the human trials described below.

This page sets out what the placebo-controlled trials, the comparisons with blood pressure drugs, and the pooled reviews found, and why they disagree; how much hibiscus the studies used and how far that is from a typical cup; and who should be careful, including people taking blood pressure, cholesterol, antimalarial, or blood-thinning medicines and people who are pregnant or breastfeeding. Results apply to roselle calyces, not to the ornamental garden hibiscus. Nothing here is medical advice. High blood pressure needs a proper diagnosis from repeated readings and a treatment plan from a clinician, because its damage builds up over years, and hibiscus should never quietly replace a prescribed medicine.

See also

The full hibiscus monograph Herbs for Heart and Circulation

02 The trials

Key studies

The trials and reviews that carry the most weight for this question, with the product and dose each one tested. Results apply to the preparation studied.

  1. Ellis et al., 2022

    Meta-analysis of 17 randomized trials

    Who
    17 trials in adults; trials with participants on medication excluded
    What and how much
    Hibiscus tea (7 trials) or capsules (10 trials), 15 mg to 9 g a day
    How long
    15 to 90 days

    Systolic pressure 7.10 mmHg lower than placebo, other teas, or diet combined (I² 95%), and 10.05 mmHg lower against placebo alone; no significant difference from blood pressure drugs.

  2. Cochrane review, 2021

    Systematic review of placebo or no-treatment trials

    Who
    One eligible trial: 60 people with type 2 diabetes and hypertension
    What and how much
    Roselle extract capsules versus lactose placebo
    How long
    8 weeks

    No clear effect on systolic pressure (mean difference 1.65 mmHg, 95% CI −7.89 to 11.19); evidence insufficient and of very low certainty.

  3. Serban et al., 2015

    Meta-analysis of 5 trials (fixed-effect)

    Who
    390 participants
    What and how much
    Hibiscus tea or extract, various doses
    How long
    Trials published to July 2014

    Systolic pressure 7.58 mmHg and diastolic 3.53 mmHg lower; effects larger at higher starting pressure.

  4. McKay et al., 2010

    Randomized, double-blind, placebo-controlled

    Who
    65 adults aged 30–70 with prehypertension or mild hypertension, not on blood pressure drugs
    What and how much
    Three 240 ml cups a day, each brewed from 1.25 g dried calyx for 6 minutes, versus a flavored placebo drink
    How long
    6 weeks

    Systolic pressure fell 7.2 mmHg versus 1.3 mmHg with placebo (p = 0.030); the diastolic difference (3.1 versus 0.5 mmHg) was not significant.

  5. Bourqui et al., 2021

    Randomized, five-arm, captopril-controlled

    Who
    219 adults with uncomplicated hypertension in Senegal
    What and how much
    Hibiscus (bissap) brew of 10 g calyx a day or 2 × 375 mg tablets, versus captopril 50 mg twice a day (plus two kinkeliba arms)
    How long
    6 months

    Systolic pressure fell 19.5 mmHg on the herbal regimens and 19.7 mmHg on captopril; 75% on bissap and 65% on captopril had a drop of at least 10 mmHg.

  6. Herrera-Arellano et al., 2007

    Randomized, double-blind, lisinopril-controlled

    Who
    193 adults with stage I or II hypertension (171 analyzed)
    What and how much
    Dried calyx extract providing 250 mg anthocyanins a day versus lisinopril 10 mg a day
    How long
    4 weeks

    Pressure fell from 146/98 to 130/86 mmHg on hibiscus, but lisinopril lowered it significantly more; plasma ACE activity fell.

  7. Herrera-Arellano et al., 2004

    Randomized, captopril-controlled

    Who
    90 adults with hypertension off treatment for at least a month (75 analyzed)
    What and how much
    Infusion of 10 g dried calyx in 0.5 L water each morning versus captopril 25 mg twice a day
    How long
    4 weeks

    Systolic pressure fell from 139 to 124 mmHg on hibiscus, with no significant difference from captopril at the end of the study.

03 Evidence

What the research shows

Promising clinical evidence

Our rating for Hibiscus for Blood Pressure, based on the studies below.

The most carefully run trial is by McKay and colleagues (Journal of Nutrition 2010) at the USDA Human Nutrition Research Center on Aging at Tufts University in Boston. It randomized 65 adults aged 30 to 70 with prehypertension or mild hypertension, none taking medicines that affect blood pressure, in a double-blind design (neither participants nor researchers knew who got which drink). Each day they drank three 240 ml servings of hibiscus tea or a placebo made from artificial cranberry and raspberry flavors with red food coloring, for six weeks. Systolic pressure fell by 7.2 mmHg with hibiscus and 1.3 mmHg with placebo (p = 0.030). Diastolic pressure (the bottom number) fell by 3.1 versus 0.5 mmHg, not a significant difference, and the change in mean arterial pressure was borderline (p = 0.054). People with higher starting systolic pressure responded more. The study was funded by the USDA Agricultural Research Service and by Celestial Seasonings, the herbal tea brand of the Hain Celestial Group, which also supplied the hibiscus; the authors declared no conflicts of interest. It was small, short, and measured readings rather than strokes or heart attacks, and trials like it remain rare: only six of the 17 trials in the largest meta-analysis compared hibiscus with a placebo.

Several trials compared hibiscus with prescription drugs, mostly in Mexico and West Africa. Herrera-Arellano and colleagues (Phytomedicine 2004), at the Mexican Social Security Institute, randomized 90 adults with hypertension who had been off treatment for at least a month to an infusion of 10 g of dried calyx in half a liter of water before breakfast or captopril 25 mg twice a day for four weeks. Fifteen withdrew, and in the 75 analyzed, systolic pressure on hibiscus fell from 139 to 124 mmHg, with no significant difference from captopril. Their double-blind follow-up (Planta Medica 2007) gave 193 adults a dried extract supplying 250 mg of anthocyanins a day or lisinopril 10 mg; on hibiscus, pressure fell from about 146/98 to 130/86 mmHg, but lisinopril lowered it significantly more. In Senegal, Seck and colleagues (Journal of Human Hypertension 2017) found that ramipril lowered systolic pressure more than hibiscus calyx capsules over four weeks (16.7 versus 11.2 mmHg). The longest trial, by Bourqui and colleagues (Journal of Human Hypertension 2021), followed 219 Senegalese patients for six months on hibiscus brew, hibiscus tablets, two forms of another local plant, kinkeliba, or captopril 50 mg twice a day; systolic pressure fell by about 19.5 mmHg on the herbal regimens and 19.7 mmHg on captopril. These results suggest a real effect, but they cannot show that hibiscus matches modern treatment. Most trials were short, several did not report blinding, and Wahabi and colleagues (Phytomedicine 2010), reviewing the four earliest randomized trials with 390 patients, judged all but one short and of poor quality.

Pooled analyses agree on the direction but not on the certainty. Serban and colleagues (Journal of Hypertension 2015) combined five trials with 390 participants and found systolic pressure 7.58 mmHg and diastolic 3.53 mmHg lower, with bigger effects at higher starting pressures, using a fixed-effect model, which assumes every trial measures the same underlying effect. Ellis and colleagues (Nutrition Reviews 2022), at the University of Leeds and funded by a university scholarship and a UK research council award, included 17 trials lasting 15 to 90 days. Against placebo, other teas, or diet combined, systolic pressure was 7.10 mmHg lower (95% confidence interval 1.20 to 13.00), but heterogeneity (how much results disagree between trials) was extreme, with an I² of 95%, and diastolic pressure was not significantly lower. Against placebo alone, systolic pressure was 10.05 mmHg lower. Doses of 1 g a day or less showed no significant effect, while trials longer than four weeks did, and the difference from blood pressure drugs was not statistically significant, which is not the same as showing equal effect. Abdelmonem and colleagues (Journal of Cardiovascular Pharmacology 2022) pooled 13 trials with 1,205 participants and found systolic and diastolic pressure 6.67 and 4.35 mmHg lower than placebo, significant in people with hypertension alone but not in those with metabolic syndrome; one author disclosed paid consulting, through a contract research organization, on behalf of Natural Wellness, relevant to the study concept. An umbrella review by Norouzzadeh and colleagues (Complementary Therapies in Medicine 2025), covering 26 trials with 1,797 participants, reported reductions that grew with dose.

Cochrane takes a stricter view. Its review, first published by Ngamjarus and colleagues in 2010, found no trials comparing hibiscus with placebo or no treatment in people with hypertension. The 2021 update by Pattanittum and colleagues, which searched to August 2021 with no language limits, including Chinese and Thai databases, found one: 60 people with type 2 diabetes given roselle extract capsules or a lactose placebo for eight weeks. It showed no clear difference in systolic pressure (mean difference 1.65 mmHg, 95% confidence interval −7.89 to 11.19), and the authors rated the evidence very low certainty because of high risk of attrition and reporting bias, imprecision, and indirectness. The reviews disagree mainly over what they count: trials in people with prehypertension, such as McKay’s, and trials against other teas, diets, or drugs fall outside Cochrane’s question. NCCIH says roselle may help reduce blood pressure in people with hypertension, but that the evidence is limited, the effects are small, and no dietary supplement has been shown to work as well as the drugs used to treat hypertension.

Little is known about hibiscus in people already taking blood pressure medicines, the group most likely to try it. McKay and colleagues excluded anyone on medicines that affect blood pressure, the 2004 Mexican trial required a month off treatment, and Ellis and colleagues excluded trials whose participants were taking medication. Two trials from Golestan University of Medical Sciences in Iran are exceptions. Dehkhoda and colleagues (Avicenna Journal of Phytomedicine 2024) gave 72 people with mild chronic kidney disease and high blood pressure valsartan 40 mg twice a day plus either a 350 mg hibiscus extract pill twice a day or hydrochlorothiazide 12.5 mg for 90 days; blood pressure fell significantly in both groups, and one author is the chief executive of a herbal medicine company. In 70 people with diabetic kidney disease, Kiani and colleagues (Avicenna Journal of Phytomedicine 2026) found that valsartan with hydrochlorothiazide lowered blood pressure more than valsartan with 500 mg of hibiscus extract. Neither trial had a placebo group. Open questions include whether any effect lasts beyond a few months, which dose and preparation work best, how safely hibiscus combines with medicines, and whether a few points off a reading means fewer strokes and heart attacks.

04 In practice

How it was taken in studies

There is no standard dose, and the trials used very different amounts. In the McKay trial each 240 ml serving was brewed from a tea bag holding 1.25 g of ground dried calyces, steeped in boiled water for six minutes, three times a day, or about 3.75 g a day. Each serving contained about 7 mg of anthocyanins, the red pigments the authors suspect contribute to the effect, and they note that this amount of hibiscus is found in a variety of commercial blended herbal teas. The 2004 Mexican trial used 10 g of dried calyx in half a liter of water once a day, supplying 9.6 mg of anthocyanins, and the six-month Senegalese trial used a brew of 10 g of calyx a day. An earlier Iranian trial, as described by McKay and colleagues, used two spoonfuls of tea per glass brewed for 20 to 30 minutes. Across the 17 trials pooled by Ellis and colleagues, daily doses ranged from 15 mg to 9 g and anthocyanins from 3 to 250 mg, and doses of 1 g a day or less showed no significant effect.

Capsules and tablets are a different product from tea. Trials used a dried extract standardized to 250 mg of anthocyanins a day (Herrera-Arellano 2007), 320 mg of powdered calyx twice a day (Seck 2017), 375 mg tablets twice a day (Bourqui 2021), and a 350 mg extract pill twice a day alongside valsartan (Dehkhoda 2024). These amounts cannot be converted into cups of tea. Trials lasted from 15 days to six months; McKay and colleagues measured blood pressure weekly and assessed the effect at six weeks, and the Mexican trials at four. In a 1999 Iranian trial of 54 patients with moderate hypertension, Haji Faraji and Haji Tarkhani (Journal of Ethnopharmacology) found that pressure rose again within three days of stopping, which suggests that any effect lasts only as long as the drinking does. A single cup, or a single reading, says little.

The strength of homemade or bought hibiscus tea varies widely with the amount of calyx, the volume of water, and the steeping time: the trials ranged from a six-minute steep of 1.25 g per cup to brews of 20 to 30 minutes and 10 g infusions. Ellis and colleagues add that hibiscus products are often poorly characterized and that their content of active compounds varies, which may explain some of the disagreement between trials. Traditional drinks are often sweetened; zobo, for example, is described as a sweetened water extract of the calyx (Kolawole and Maduenyi 2004), whereas the trials used unsweetened tea or capsules. If you have raised readings and want to try hibiscus, treat it as one small part of the lifestyle changes NCCIH lists, such as healthy eating, physical activity, a healthy weight, limiting alcohol, and managing stress. Agree it with your clinician, keep taking any prescribed medicine, and check home readings before and after several weeks so that both a benefit and an excessive fall are noticed.

05 Caution

Before you try hibiscus

In trials hibiscus has been well tolerated, although the trials were small and short and not designed to detect rare harms. Herrera-Arellano and colleagues reported 100% tolerability in both Mexican trials, and the 2007 trial found no abnormal changes in liver or kidney blood tests; a Nigerian trial comparing hibiscus with hydrochlorothiazide in 80 people reported no side effects (Nwachukwu and colleagues, Nigerian Journal of Clinical Practice 2015). The 2025 umbrella review found a minor rise in the liver enzyme AST (aspartate aminotransferase), judged clinically insignificant, without more adverse events. In the 2007 trial serum chloride rose and sodium tended to fall, with no change in potassium, and the 2004 infusion increased sodium in the urine, consistent with a mild diuretic (water pill) effect. LactMed notes that allergic reactions are possible, including cross-reactions with other plants of the mallow family (Malvaceae), such as marshmallow and ambrette.

Pregnancy: there are no human safety data. In rats, Iyare and Adegoke (Nigerian Journal of Physiological Sciences 2008) linked hibiscus extract in the drinking water during pregnancy to delayed puberty and higher body mass index at puberty in female offspring, along with raised maternal sodium and corticosterone, and de Arruda and colleagues (Drug and Chemical Toxicology 2016) found reduced sperm production in male offspring of rats given 250 or 500 mg/kg from mid-pregnancy through lactation. These doses do not translate simply to a cup of tea, but capsules, extracts, and medicinal amounts are best avoided in pregnancy, and high blood pressure in pregnancy always needs a midwife or doctor. Breastfeeding: LactMed, a US government database run by the National Institute of Child Health and Human Development, says no data exist on hibiscus passing into breast milk or on its safety for nursing mothers or infants; it notes that hibiscus is generally recognized as safe as a food in the US and that no valid trials support its use to boost milk supply. Children: we found no trials of hibiscus for blood pressure in children, and raised readings in a child need specialist assessment. People with low blood pressure, those prone to fainting or dizziness on standing, people with kidney disease or on fluid restrictions, and anyone taking several blood pressure drugs should use hibiscus only with medical advice.

Blood pressure medicines: hibiscus may add to their effect, although no human study has measured the interaction directly. In hypertensive rats, Alam and colleagues (Journal of Pharmacy and Pharmacology 2021) found that hibiscus with amlodipine lowered pressure more than either alone and raised amlodipine exposure from 81.8 to 125.0 ng·h/mL. In rats and rabbits, Ndu and colleagues (Journal of Medical Food 2011) found that hibiscus extract with hydrochlorothiazide increased urine output and raised and prolonged blood levels of the diuretic, and in the 2007 trial hibiscus lowered plasma ACE activity, the enzyme blocked by lisinopril and captopril. Other drugs: Showande and colleagues (Journal of Clinical Pharmacy and Therapeutics 2017) gave six healthy volunteers 40 mg of simvastatin with and without a hibiscus drink; total exposure fell by about a third, and the authors advised against combining them until more data exist. Mahmoud and colleagues (Journal of Antimicrobial Chemotherapy 1994) found that taking 600 mg of chloroquine with karkadi, the Sudanese hibiscus drink, cut exposure from 7.52 to 2.16 mg·h/L, enough to expect weaker antimalarial protection. Zobo drunk before 1 g of acetaminophen sped its elimination in six men, raising clearance by about 12% without changing absorption (Kolawole and Maduenyi, European Journal of Drug Metabolism and Pharmacokinetics 2004). A 2026 case report describes a markedly raised INR in a 59-year-old woman on warfarin after drinking hibiscus tea, which returned to normal after warfarin was paused, hibiscus stopped, and vitamin K given (Bani Yaseen and colleagues, Cureus 2026). One case cannot prove cause, but anyone on warfarin should tell their anticoagulation clinic before starting or stopping regular hibiscus.

Hibiscus is not for emergencies and not a substitute for treatment. The American Heart Association advises that if a reading is higher than 180/120 mmHg, you wait a minute and measure again; if it is still that high and you have chest pain, shortness of breath, back pain, numbness, weakness, a change in vision, or difficulty speaking, call 911 or your local emergency number rather than waiting to see whether it comes down. A reading that high without symptoms still needs prompt contact with your health care professional. See a doctor, too, if home readings stay raised, if you feel dizzy or faint after adding hibiscus to your medicines, or if you are pregnant and your blood pressure rises. Never stop or reduce a prescribed blood pressure medicine because your readings improve on hibiscus: NCCIH advises following the treatment plan from your provider and not replacing it with an unproven product, and better readings may simply mean the medicine is working.

06 Questions

Frequently Asked Questions

Probably a little, in people whose blood pressure is mildly raised. In a six-week US trial, three cups of hibiscus tea a day lowered systolic pressure by 7.2 mmHg against 1.3 mmHg on a placebo drink. Meta-analyses find average drops of about 7 mmHg, largest in people with higher readings, but results vary widely between trials. Cochrane found only one eligible placebo-controlled trial in people with hypertension and judged the evidence insufficient. No trial has shown that hibiscus prevents strokes or heart attacks.

The US trial used three 240 ml cups a day, each brewed from 1.25 g of dried calyx steeped for six minutes. Mexican and Senegalese trials used 10 g of calyx a day, and others used capsules. Doses of 1 g a day or less showed no clear effect in pooled trials. Effects were measured after four to six weeks, and in one trial pressure rose again within three days of stopping, so a single cup tells you little.

Only with your prescriber’s knowledge. Hibiscus may add to the effect of blood pressure drugs: in animal studies it boosted amlodipine and raised hydrochlorothiazide levels, and in people it lowered the activity of ACE, the enzyme blocked by drugs such as lisinopril. Almost all trials excluded people already on treatment, so the combination is largely untested. If you try it, check home readings and report dizziness or fainting. Never stop or reduce a prescribed medicine on your own.

No. Four-week trials found hibiscus comparable to captopril but less effective than lisinopril and ramipril, and reviewers judged most early trials short and of poor quality. A six-month trial in Senegal found similar falls with hibiscus and captopril, but no trial has shown that hibiscus prevents strokes or heart attacks. NCCIH says no supplement works as well as blood pressure drugs. Other herbs promoted for blood pressure, such as garlic, also have only modest effects.

As an ordinary drink it has been well tolerated in trials, but it is not inert. It may add to blood pressure medicines, and in small studies it cut simvastatin exposure by about a third and chloroquine by about 70%. A 2026 case report links it to a markedly raised INR in a woman on warfarin. People with low blood pressure, kidney disease, or a mallow-family allergy, and those who are pregnant, should be cautious. Sweetened versions add sugar.

It has not been studied in pregnant or breastfeeding women. Rat studies linked hibiscus extract in pregnancy to delayed puberty in female offspring and reduced sperm production in male offspring, at doses far above a cup of tea. LactMed says nothing is known about hibiscus in breast milk and that no valid trials support its use to boost milk supply. Capsules, extracts, and medicinal amounts are best avoided; ask your midwife or doctor about occasional drinks.

07 References

Sources

These references support the claims on this page. They are not an endorsement of any product. The hibiscus monograph carries its own full source list.

  1. Roselle for hypertension in adults

    Cochrane Database of Systematic Reviews (PubMed 34837382), 2021

    Pattanittum et al.: update of the 2010 review by Ngamjarus et al. that found no eligible trials; one RCT (60 people with type 2 diabetes, eight weeks) qualified; SBP mean difference 1.65 mmHg; evidence insufficient, very low certainty.

  2. A systematic review and meta-analysis of the effects of Hibiscus sabdariffa on blood pressure and cardiometabolic markers

    Nutrition Reviews (PubMed 34927694), 2022

    Ellis et al.: 17 trials; SBP −7.10 mmHg against placebo, other teas, or diet combined (I² 95%), −10.05 mmHg against placebo alone; no effect at 1 g a day or less; medicated participants excluded; university and BBSRC funding.

  3. Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension: a systematic review and meta-analysis of randomized controlled trials

    Journal of Hypertension (PubMed 25875025), 2015

    Serban et al.: five RCTs, 390 participants; fixed-effect analysis found SBP 7.58 mmHg and DBP 3.53 mmHg lower; effects inversely related to baseline pressure.

  4. Efficacy of Hibiscus sabdariffa on Reducing Blood Pressure in Patients With Mild-to-Moderate Hypertension: A Systematic Review and Meta-Analysis of Published Randomized Controlled Trials

    Journal of Cardiovascular Pharmacology (PubMed 34694241), 2022

    Abdelmonem et al.: 13 RCTs, 1,205 participants; SBP −6.67 and DBP −4.35 mmHg versus placebo; not significant in metabolic syndrome or versus active controls; one author consulted on behalf of Natural Wellness.

  5. Hibiscus sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adults

    Journal of Nutrition (PubMed 20018807), 2010

    McKay et al.: 65 adults not on blood pressure drugs; 3 × 240 ml a day of tea brewed from 1.25 g for 6 minutes; SBP −7.2 vs −1.3 mmHg; funded by USDA ARS and Celestial Seasonings, which supplied the hibiscus.

  6. Hypertension treatment with Combretum micranthum or Hibiscus sabdariffa, as decoction or tablet: a randomized clinical trial

    Journal of Human Hypertension (PubMed 32948827), 2021

    Bourqui et al.: 219 Senegalese patients for six months; bissap brew (10 g calyx a day) or tablets versus captopril 50 mg twice a day; SBP falls of 19.5 and 19.7 mmHg; 75% versus 65% with a drop of at least 10 mmHg.

  7. 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 (PubMed 17315307), 2007

    Herrera-Arellano et al.: 193 adults; extract with 250 mg anthocyanins versus lisinopril 10 mg for four weeks; 146/98 to 130/86 mmHg but less than lisinopril; ACE activity, chloride, and sodium changes; no liver or kidney test abnormalities.

  8. Effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa in patients with mild to moderate hypertension: a controlled and randomized clinical trial

    Phytomedicine (PubMed 15330492), 2004

    Herrera-Arellano et al.: 90 enrolled, 75 analyzed; 10 g calyx in 0.5 L water (9.6 mg anthocyanins) daily versus captopril 25 mg twice daily for four weeks; no significant difference; natriuretic effect; 100% tolerability.

  9. Roselle (Hibiscus sabdariffa L.) extract as an adjunct to valsartan in patients with mild chronic kidney disease: A double-blind randomized controlled clinical trial

    Avicenna Journal of Phytomedicine (PubMed 38952776), 2024

    Dehkhoda et al.: 72 people with CKD and high blood pressure; 350 mg hibiscus extract twice daily or hydrochlorothiazide 12.5 mg, each with valsartan, for 90 days; both lowered pressure; one author heads a herbal company.

  10. In vivo pharmacodynamic and pharmacokinetic interactions of Hibiscus sabdariffa calyces extracts with simvastatin

    Journal of Clinical Pharmacy and Therapeutics (PubMed 28925046), 2017

    Showande et al.: in six healthy volunteers, a hibiscus beverage raised simvastatin clearance by 44.6% and cut peak levels by 18% (AUC ratio 0.646); co-administration discouraged.

  11. Significant reduction in chloroquine bioavailability following coadministration with the Sudanese beverages Aradaib, Karkadi and Lemon

    Journal of Antimicrobial Chemotherapy (PubMed 8089046), 1994

    Mahmoud et al.: chloroquine 600 mg with karkadi gave an AUC of 2.16 versus 7.52 mg·h/L with water in healthy men; reduced antimalarial efficacy expected.

  12. Hibiscus

    Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (PubMed 30000942), 2025

    No data on excretion into breast milk or safety in nursing mothers or infants; no valid trials support use as a galactogogue; GRAS as a food; possible allergic cross-reaction with other Malvaceae.

  13. When To Call 911 About High Blood Pressure

    American Heart Association, 2025

    Readings higher than 180/120 mmHg: recheck after a minute; call 911 with chest pain, shortness of breath, back pain, numbness, weakness, vision change, or difficulty speaking; otherwise contact a health care professional promptly.

  14. Hypertension (High Blood Pressure)

    National Center for Complementary and Integrative Health (NIH), 2018

    Roselle may help reduce blood pressure but evidence is limited and effects small; no supplement matches antihypertensive drugs; follow the prescribed treatment plan and tell providers about supplements.

All evidence reviews →