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Hibiscus tea and blood pressure: what the trials really show
In pooled trials, hibiscus tea lowered systolic pressure by about 7 mmHg compared with placebo or no treatment. The effect was largest in people with higher readings, and results varied a lot between studies. No trial settled on a best dose. It is a modest helper at most, never a swap for prescribed medicine.
Written by the Cardio Slim Tea reading deskUpdated · 8 min read
The plant
What is hibiscus tea?
Hibiscus tea is a tart, ruby-red drink made from the dried calyces of Hibiscus sabdariffa, also called roselle or sour tea. It is popular in Mexico, the Caribbean, West Africa and the Middle East.
The calyx is the cup of leaf-like parts that holds the flower. Dried, it brews a sour, cranberry-like cup that many people drink hot or iced. It has no caffeine of its own.
Researchers became curious about it because people in several countries had long used it for heart health. That tradition led to small clinical trials, and later to reviews that pooled those trials together.
Review one
What did the first big hibiscus review find?
A 2015 meta-analysis pooled 5 randomized trials with 390 people. Hibiscus lowered systolic pressure by about 7.6 mmHg and diastolic pressure by about 3.5 mmHg (Serban 2015 - Hibiscus BP meta-analysis).
Systolic is the top number, the pressure when your heart beats. Diastolic is the bottom number, the pressure between beats.
The authors were careful. They said more well-designed trials were needed to confirm the results (Serban 2015 - Hibiscus BP meta-analysis). Five trials is a small base, and small trials can make an effect look bigger than it is.
Review two
Did a larger review confirm it?
Mostly, yes, with more caveats. A 2021 review of 17 trials found hibiscus lowered systolic pressure by about 7.1 mmHg compared with placebo (Ellis 2021 - Hibiscus BP meta-analysis). The effect was biggest in people who started with higher readings.
| Detail | 2015 review (Serban 2015 - Hibiscus BP meta-analysis) | 2021 review (Ellis 2021 - Hibiscus BP meta-analysis) |
|---|---|---|
| Trials pooled | 5 | 17 |
| People | 390 | Not pooled into one total |
| Systolic change | About -7.6 mmHg | About -7.1 mmHg vs placebo |
| Diastolic change | About -3.5 mmHg | See the full paper |
| Vs blood pressure drugs | Not compared | Small, not significant differences in a few trials |
| Main caution | Few, small trials | Very high variation between trials; no settled dose |
The variation matters. The 2021 authors measured very high heterogeneity, meaning trials disagreed a lot about the size of the effect (Ellis 2021 - Hibiscus BP meta-analysis). Brewing methods, doses, trial length and the people studied all differed. The pooled 7 mmHg is an average across very different studies.
A few small trials compared hibiscus with blood pressure medicines and found differences too small to call (Ellis 2021 - Hibiscus BP meta-analysis). That is not proof the two are equal. Small trials cannot rule out a real gap, and drugs have far larger bodies of evidence.
Reading the numbers
How should you read a 7 mmHg drop?
As a modest, average change, not a promise for any one person. mmHg means millimeters of mercury, the unit on every blood pressure cuff.
- It is an average
Some people in the trials saw more, some less, some none. Your own result could fall anywhere in that range.
- It depends on where you start
The biggest drops came in people with higher readings (Ellis 2021 - Hibiscus BP meta-analysis). Someone at 125/78 should not expect what someone at 150/95 might see.
- It may not cross a category line
A move from 146 to 139 shifts a reading from stage 2 to stage 1 by the AHA chart (AHA - Blood pressure readings). That still needs care.
- Compare it to proven habits
The DASH diet lowered pressure by about 11.4/5.5 mmHg in people with hypertension within eight weeks (Appel 1997 - DASH trial).
Home readings bounce from minute to minute. Take two readings one minute apart and write both down (AHA - Blood pressure readings). A single cup and a single reading tell you very little. See the full chart on blood pressure numbers.
Dose
How much hibiscus tea did the trials use?
The doses varied, and no best dose has been agreed. The 2021 review said more research is needed to pin down an effective amount and length of use (Ellis 2021 - Hibiscus BP meta-analysis).
That leaves anyone brewing hibiscus at home guessing. It also makes blends harder to judge. Cardio Slim Tea names hibiscus among 14 herbs but prints no amount for it. A 60 g pouch sold as about a month works out to roughly 2 g of tea a day for all herbs together, by our math. How much of that is hibiscus is not published.
A tea that lists hibiscus is not the same as a hibiscus trial. Read more about this herb on the hibiscus page.
Cardio Slim Tea: from $49 a pouch60 g herbal tea · 2, 3 or 6 pouches · 60-day money-back guarantee
See packsSafety
Is hibiscus tea safe to drink every day?
For most healthy adults, a cup of hibiscus tea is a common food drink. The bigger questions are about medicines and existing conditions.
- If you take blood pressure medicine, hibiscus may add to its effect. Watch for dizziness when you stand.
- If you are pregnant or nursing, ask your doctor first, since safety data are limited.
- If your readings are over 180/120 with chest pain, shortness of breath or vision changes, call 911 (AHA - Blood pressure readings).
Keep taking your prescribed blood pressure medicine. Never stop or cut a dose because of a tea; talk to your healthcare professional first (AHA - Types of BP medications). Read tea and blood pressure medicines for more.
Labels and ads
Can a hibiscus tea be sold as a blood pressure treatment?
No. A supplement may say it "supports healthy blood pressure" with the FDA disclaimer (21 CFR 101.93 - Structure/function claims). It may not claim to treat high blood pressure.
In 2021 the FDA warned a tea seller that calling hibiscus "a proven blood-pressure reducer" made its teas unapproved drugs (FDA warning letter - TeaTaze (BP claims)). Cardio Slim Tea's pouch uses the structure and function wording with the asterisk. Its sales page goes further with a story of large drops, but cites no study (Cardio Slim Tea sales page).
Bottom line
So is hibiscus tea worth drinking?
It can be a pleasant, caffeine-free habit with modest research behind it. Treat it as one small piece next to DASH eating, less salt, regular walks, good sleep and any medicine you are prescribed (NHLBI - High BP treatment). Track your readings, share them with your doctor, and let the numbers guide you.
FAQ
Hibiscus tea and blood pressure: FAQ
How much can hibiscus tea lower blood pressure?
In a review of 17 trials, hibiscus lowered systolic pressure by about 7 mmHg versus placebo on average (Ellis 2021 - Hibiscus BP meta-analysis). An earlier 5-trial review found about 7.6/3.5 mmHg (Serban 2015 - Hibiscus BP meta-analysis). Results varied widely, and people with higher readings tended to see larger changes.
How long does hibiscus tea take to affect blood pressure?
The trials ran for weeks, not days, and they differed in length, so there is no fixed timeline. A single cup is not expected to show a lasting change. Track home readings over several weeks and share them with your doctor.
Can I drink hibiscus tea with blood pressure medicine?
Ask your doctor or pharmacist first. Hibiscus may add to the effect of blood pressure drugs, which could leave some people dizzy. Never stop or lower a prescribed dose on your own; any change belongs with your healthcare professional (AHA - Types of BP medications).
Is hibiscus tea as good as blood pressure medicine?
No, that has not been shown. A few small trials found no significant difference (Ellis 2021 - Hibiscus BP meta-analysis), but small trials cannot prove two treatments are equal. Medicines are tested in far larger studies, and hibiscus has no settled dose.
How many cups of hibiscus tea a day did studies use?
The amounts varied between trials, and reviewers said an effective dose and duration still need to be established (Ellis 2021 - Hibiscus BP meta-analysis). For a packaged blend, follow the directions printed on your pouch rather than a number from a study.
How much hibiscus is in Cardio Slim Tea?
The amount is not published. Hibiscus is one of 14 herbs the seller names, and the pouch front shows only a net weight of 60 g. By our math that is about 2 g of tea a day for all ingredients together.
Does hibiscus tea have caffeine?
Pure hibiscus tea has no caffeine of its own. Blends can differ, though. Cardio Slim Tea also lists oolong, which naturally contains caffeine, and no caffeine amount is published for the blend.
Who wrote this
Written and reviewed by
Pages built from the pouch, the brand graphic, the sales page and linked NIH, FDA, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by an authorized U.S. retailer, not by the manufacturer. We earn money when you buy through our order links.
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