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Supplement · Grade B

Hibiscus Extract and medications.

Every documented pair, every citation. Below: 2 documented pairs grouped by mechanism.

Hibiscus Extract is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.

Hibiscus extract comes from the dried calyces of Hibiscus sabdariffa, the same plant behind sour or roselle tea. It has Grade B evidence for lowering blood pressure, both systolic and diastolic, and offers some antioxidant and mild lipid effects. A 2015 meta-analysis of five RCTs found systolic reductions of around 7.6 mmHg, and trials in prehypertensive and diabetic hypertensive adults showed meaningful drops, so it may support people working on blood pressure alongside diet. The honest limit is that effect sizes vary with dose and baseline, and the strongest results come from people who already had raised pressure. On interactions, the effect that matters is additive: taken with antihypertensive medicines it can lower pressure further, so monitoring is sensible, and there is some pharmacokinetic interaction with hydrochlorothiazide. Hepatotoxicity is only a concern at very high doses. If you take blood pressure medication, it is worth flagging to your GP and keeping an eye on readings rather than assuming the two simply add up safely.

Below are the 2 documented pairs we have explicitly assessed for Hibiscus Extract: 2 amber. The pairs cluster around 1 mechanism: Additive blood-pressure lowering. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.

Documented interactions

Additive blood-pressure lowering

Amber Amlodipine

Hibiscus tends to lower blood pressure on its own, and amlodipine lowers it by relaxing blood vessels. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. If symptoms appear, tell your GP.

PMID 20018807 · PMID 25875025 · PMID 39870328 · BNF: Amlodipine

Reviewer-flagged: awaiting clinical-reviewer sign-off.

Amber Ramipril

Hibiscus tends to lower blood pressure on its own, and ramipril lowers it by blocking the angiotensin-converting enzyme. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. If symptoms appear, tell your GP.

Reviewer-flagged: awaiting clinical-reviewer sign-off.

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.
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How we decide

How we grade severity, choose what's in scope, and what we exclude.

Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.

Read the full methodology
Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.