Last Updated: September 28 2022

Hibiscus Sabdariffa (Roselle or Sour Tea) is a tea where the usually dark colored flowers are used to brew. It appears to inhibit carbohydrate absorption to a degree and appears to be effective in reducing blood pressure.

Roselle is most often used for


Hibiscus Sabdariffa (Roselle) is a supplemental herb that is derived from the plant's calyces, which are the collection of sepals separating the blooming flower from the stem. The calyces have traditionally been steeped into tea where the anthocyanins (red-blue pigmentation) is steeped into the water and drank for medicinal purposes.

Although Roselle has a variety of claims medicinally, it appears to have evidence to support its role in reducing blood pressure in persons with elevated blood pressure. This may be through its ACE inhibitory potential (although this is admittedly weak) or by benefiting the endothelium via nitric oxide related mechanisms (appears to be in better accordance with the amount of anthocyanins that reach the blood). Reductions in both diastolic and systolic blood pressure have been noted, and for the most part appear to be reliable in presence although not so much in magnitude of benefit (ie. blood pressure is reliably reduced, but the degree of reduction seems to vary).

In regards to diabetes and blood glucose control, Roselle appears to have limited evidence to support these claims but the evidence is so far in support. Mechanisms are not known, and the remarkable potency in animal studies seems to be markedly less in the limited human interventions looking at it. Roselle does appear to weakly inhibit carbohydrate absorption enzymes, yet is synergistic with Morus Alba (White Mulberry) in doing so; a tea made of White Mulberries and Roselle, although currently not supported in vivo, is possibly an effective carbohydrate absorption inhibitory tea.

The interactions of Roselle and weight loss are not too clear-cut, and it seems to be highly intertwined with studies on Roselle toxicity; Roselle is known to be toxic in higher doses, and weight loss more often than not precedes chronic toxicity. For studies that note weight loss without toxicity, it seems to be related to reduced food intake in rats and mice rather than direct fat burning effects.

The appetite suppressing effects seem to be fairly reliable in rats, but caution should be taken in applying these effects to humans. Aside from not being reported as a side-effect in any human study, the bioactive known as Hibiscus Acid is similarly structured to (-)-Hydroxycitric acid from Garcinia Cambogia which is known to reduce appetite in rats reliably but not humans.

Low doses of Roselle tea or supplements appear to be effective in reducing blood pressure, and may be anti-diabetic. It is unlikely that Roselle can cause weight loss independent of a reduction of appetite

The toxicity itself seems to occur in mice and rats in a similar idea as the blood pressure reducing effects in humans, as in they occur reliably although the dose required to induce toxicity and what exactly occurs seems to vary from one study to another. This may be related to the exact molecules mediating toxicity not being known right now. For the majority of toxic effects, the lowest they have occurred is 200mg/kg in rats (2.2g dried calyx for a 150lb human). Human studies have used this dose or above with no apparent side effects though. The toxicity of these doses of Roselle need to be evaluated more.

One concern that does exist is testicular toxicity, which occurs fairly reliably at 200mg/kg or above in animals but has not been investigated in humans. Roselle appears to be anti-fertility in men, inducing abnormal sperm morphology. In females, there was a series of studies suggesting Roselle could cause abnormal (higher) birth weights in offspring with a delay of pubertal onset; for the most part these are attributed to the appetite suppressing effect causing maternal malnutrition, with no per se mechanisms harming the pup (via lactation) currently known.

Although these toxic effects can possibly be avoided by adhering to proper dosing, the amount of safety information in humans is not as expansive as would be desired; the therapeutic threshold (degree of 'safety buffer' between the active dose and toxic dose) is also lower than desirable, so possible toxic effects with overdosing Roselle is probably more relevant than other supplements.

Higher doses of Roselle do exert toxic effects, although none of these toxic effects have been reported in humans (that being said, they have not conclusively been disproven either). It would be prudent to avoid taking too much Roselle, especially since many benefits of Roselle (elaborating on in complete summary) are not dose-dependent above the lowest observable toxic dose of 2.2g/150lb human

What else is Roselle known as?
Note that Roselle is also known as:
  • Roselle
  • Isakpa
  • Krachiap Daeng
  • Sour Tea
  • Hibiscus Sabdariffa
Roselle should not be confused with:
Dosage information

When using Hibiscus Sabdariffa as a tea, a dried calyx (the part of the blooming top of a flower that is not the petals, but beneath them) weighing about a gram is steeped into tea; drunk either once in the morning or twice a day with 8 hours between doses.

Supplemental Hibiscus Sabdariffa is taken according to the content of anthocyanins; 10mg of anthocyanins derived from Hibiscus Sabradiffa (which would be 1g of a 1% extract or 500mg of a 2% extract) appears to be effective.

Higher doses are associated with toxicity in rats, and it would be prudent to not exceed the above doses unnecessarily.

Examine Database
1.^Sčančar J, Zuliani T, Zigon D, Milačič RNi speciation in tea infusions by monolithic chromatography-ICP-MS and Q-TOF-MSAnal Bioanal Chem.(2012 Dec 13)
3.^Haji Faraji M, Haji Tarkhani AThe effect of sour tea (Hibiscus sabdariffa) on essential hypertensionJ Ethnopharmacol.(1999 Jun)
4.^Seujange Y, Leelahavanichkul A, Yisarakun W, Khawsuk W, Meepool A, Phamonleatmongkol P, Saechau W, Onlamul W, Tantiwarattanatikul P, Oonsook W, Eiam-Ong S, Eiam-Ong SHibiscus Sabdariffa Linnaeus Aqueous Extracts Attenuate the Progression of Renal Injury in 5/6 Nephrectomy RatsRen Fail.(2012 Nov 19)
8.^Bassey RB, Bakare AA, Peter AI, Oremosu AA, Osinubi AAFactors influencing extract of Hibiscus sabdariffa staining of rat testesBiotech Histochem.(2012 Aug)
12.^Beltrán-Debón R, Alonso-Villaverde C, Aragonès G, Rodríguez-Medina I, Rull A, Micol V, Segura-Carretero A, Fernández-Gutiérrez A, Camps J, Joven JThe aqueous extract of Hibiscus sabdariffa calices modulates the production of monocyte chemoattractant protein-1 in humansPhytomedicine.(2010 Mar)
13.^Fernández-Arroyo S, Herranz-López M, Beltrán-Debón R, Borrás-Linares I, Barrajón-Catalán E, Joven J, Fernández-Gutiérrez A, Segura-Carretero A, Micol VBioavailability study of a polyphenol-enriched extract from Hibiscus sabdariffa in rats and associated antioxidant statusMol Nutr Food Res.(2012 Oct)
14.^Jiménez-Ferrer E, Alarcón-Alonso J, Aguilar-Rojas A, Zamilpa A, Jiménez-Ferrer C I, Tortoriello J, Herrera-Ruiz MDiuretic Effect of Compounds from Hibiscus sabdariffa by Modulation of the Aldosterone ActivityPlanta Med.(2012 Dec)
15.^Frank T, Netzel G, Kammerer DR, Carle R, Kler A, Kriesl E, Bitsch I, Bitsch R, Netzel MConsumption of Hibiscus sabdariffa L. aqueous extract and its impact on systemic antioxidant potential in healthy subjectsJ Sci Food Agric.(2012 Aug 15)
16.^Saeed IA, Ali L, Jabeen A, Khasawneh M, Rizvi TA, Ashraf SSEstrogenic activities of ten medicinal herbs from the middle EastJ Chromatogr Sci.(2013 Jan)
17.^Herranz-López M, Fernández-Arroyo S, Pérez-Sanchez A, Barrajón-Catalán E, Beltrán-Debón R, Menéndez JA, Alonso-Villaverde C, Segura-Carretero A, Joven J, Micol VSynergism of plant-derived polyphenols in adipogenesis: perspectives and implicationsPhytomedicine.(2012 Feb 15)
18.^Wang ML, Morris B, Tonnis B, Davis J, Pederson GAAssessment of oil content and fatty acid composition variability in two economically important Hibiscus speciesJ Agric Food Chem.(2012 Jul 4)
19.^Mohamed R, Fernández J, Pineda M, Aguilar MRoselle (Hibiscus sabdariffa) seed oil is a rich source of gamma-tocopherolJ Food Sci.(2007 Apr)
20.^Cisse M, Vaillant F, Acosta O, Dhuique-Mayer C, Dornier MThermal degradation kinetics of anthocyanins from blood orange, blackberry, and roselle using the arrhenius, eyring, and ball modelsJ Agric Food Chem.(2009 Jul 22)
21.^Mourtzinos I, Makris DP, Yannakopoulou K, Kalogeropoulos N, Michali I, Karathanos VTThermal stability of anthocyanin extract of Hibiscus sabdariffa L. in the presence of beta-cyclodextrinJ Agric Food Chem.(2008 Nov 12)
22.^Frank T, Janssen M, Netzel M, Strass G, Kler A, Kriesl E, Bitsch IPharmacokinetics of anthocyanidin-3-glycosides following consumption of Hibiscus sabdariffa L. extractJ Clin Pharmacol.(2005 Feb)
23.^Rechner AR, Kuhnle G, Hu H, Roedig-Penman A, van den Braak MH, Moore KP, Rice-Evans CAThe metabolism of dietary polyphenols and the relevance to circulating levels of conjugated metabolitesFree Radic Res.(2002 Nov)
28.^Inuwa I, Ali BH, Al-Lawati I, Beegam S, Ziada A, Blunden GLong-term ingestion of Hibiscus sabdariffa calyx extract enhances myocardial capillarization in the spontaneously hypertensive ratExp Biol Med (Maywood).(2012 May 1)
29.^Zhang R, Crump J, Reisin ERegression of left ventricular hypertrophy is a key goal of hypertension managementCurr Hypertens Rep.(2003 Aug)
31.^Ajay M, Chai HJ, Mustafa AM, Gilani AH, Mustafa MRMechanisms of the anti-hypertensive effect of Hibiscus sabdariffa L. calycesJ Ethnopharmacol.(2007 Feb 12)
32.^Ojeda D, Jiménez-Ferrer E, Zamilpa A, Herrera-Arellano A, Tortoriello J, Alvarez LInhibition of angiotensin convertin enzyme (ACE) activity by the anthocyanins delphinidin- and cyanidin-3-O-sambubiosides from Hibiscus sabdariffaJ Ethnopharmacol.(2010 Jan 8)
34.^Herrera-Arellano A, Miranda-Sánchez J, Avila-Castro P, Herrera-Alvarez S, Jiménez-Ferrer JE, Zamilpa A, Román-Ramos R, Ponce-Monter H, Tortoriello JClinical effects produced by a standardized herbal medicinal product of Hibiscus sabdariffa on patients with hypertension. A randomized, double-blind, lisinopril-controlled clinical trialPlanta Med.(2007 Jan)
35.^Mozaffari-Khosravi H, Jalali-Khanabadi BA, Afkhami-Ardekani M, Fatehi F, Noori-Shadkam MThe effects of sour tea (Hibiscus sabdariffa) on hypertension in patients with type II diabetesJ Hum Hypertens.(2009 Jan)
36.^Hernández-Pérez F, Herrera-Arellano ATherapeutic use Hibiscus sabadariffa extract in the treatment of hypercholesterolemia. A randomized clinical trialRev Med Inst Mex Seguro Soc.(2011 Sep-Oct)
37.^Gurrola-Díaz CM, García-López PM, Sánchez-Enríquez S, Troyo-Sanromán R, Andrade-González I, Gómez-Leyva JFEffects of Hibiscus sabdariffa extract powder and preventive treatment (diet) on the lipid profiles of patients with metabolic syndrome (MeSy)Phytomedicine.(2010 Jun)
38.^Mozaffari-Khosravi H, Jalali-Khanabadi BA, Afkhami-Ardekani M, Fatehi FEffects of sour tea (Hibiscus sabdariffa) on lipid profile and lipoproteins in patients with type II diabetesJ Altern Complement Med.(2009 Aug)
40.^Carvajal-Zarrabal O, Waliszewski SM, Barradas-Dermitz DM, Orta-Flores Z, Hayward-Jones PM, Nolasco-Hipólito C, Angulo-Guerrero O, Sánchez-Ricaño R, Infanzón RM, Trujillo PRThe consumption of Hibiscus sabdariffa dried calyx ethanolic extract reduced lipid profile in ratsPlant Foods Hum Nutr.(2005 Dec)
41.^el-Saadany SS, Sitohy MZ, Labib SM, el-Massry RABiochemical dynamics and hypocholesterolemic action of Hibiscus sabdariffa (Karkade)Nahrung.(1991)
42.^Yang MY, Peng CH, Chan KC, Yang YS, Huang CN, Wang CJThe hypolipidemic effect of Hibiscus sabdariffa polyphenols via inhibiting lipogenesis and promoting hepatic lipid clearanceJ Agric Food Chem.(2010 Jan 27)
43.^Carvajal-Zarrabal O, Hayward-Jones PM, Orta-Flores Z, Nolasco-Hipólito C, Barradas-Dermitz DM, Aguilar-Uscanga MG, Pedroza-Hernández MFEffect of Hibiscus sabdariffa L. dried calyx ethanol extract on fat absorption-excretion, and body weight implication in ratsJ Biomed Biotechnol.(2009)
45.^Alarcon-Aguilar FJ, Zamilpa A, Perez-Garcia MD, Almanza-Perez JC, Romero-Nuñez E, Campos-Sepulveda EA, Vazquez-Carrillo LI, Roman-Ramos REffect of Hibiscus sabdariffa on obesity in MSG miceJ Ethnopharmacol.(2007 Oct 8)
46.^Ali BH, Al-Lawati I, Beegam S, Ziada A, Al Salam S, Nemmar A, Blunden GEffect of Hibiscus sabdariffa and its anthocyanins on some reproductive aspects in ratsNat Prod Commun.(2012 Jan)
47.^Alarcón-Alonso J, Zamilpa A, Aguilar FA, Herrera-Ruiz M, Tortoriello J, Jimenez-Ferrer EPharmacological characterization of the diuretic effect of Hibiscus sabdariffa Linn (Malvaceae) extractJ Ethnopharmacol.(2012 Feb 15)
49.^Prasongwatana V, Woottisin S, Sriboonlue P, Kukongviriyapan VUricosuric effect of Roselle (Hibiscus sabdariffa) in normal and renal-stone former subjectsJ Ethnopharmacol.(2008 May 22)
53.^Adisakwattana S, Ruengsamran T, Kampa P, Sompong WIn vitro inhibitory effects of plant-based foods and their combinations on intestinal α-glucosidase and pancreatic α-amylaseBMC Complement Altern Med.(2012 Jul 31)
54.^Mohagheghi A, Maghsoud S, Khashayar P, Ghazi-Khansari MThe effect of hibiscus sabdariffa on lipid profile, creatinine, and serum electrolytes: a randomized clinical trialISRN Gastroenterol.(2011)
55.^Fakeye TO, Pal A, Bawankule DU, Yadav NP, Khanuja SPToxic effects of oral administration of extracts of dried calyx of Hibiscus sabdariffa Linn. (Malvaceae)Phytother Res.(2009 Mar)