Drug & supplement interaction

Hibiscus Sabdariffa + Trandolapril, Verapamil

Trandolapril, Verapamil brand name: Tarka.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Trandolapril, Verapamil falls into 4 drug categories that Hibiscus Sabdariffa can interact with; the most serious is rated moderate. Theoretically, taking Hibiscus sabdariffa with antihypertensive drugs might increase the risk of hypotension.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions4
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Hibiscus Sabdariffa and Trandolapril, Verapamil

These two interact in 4 distinct ways. Each one is explained separately below.

Why Are There 4 Interactions?

Hibiscus Sabdariffa interacts with whole categories of medication. Trandolapril, Verapamil falls into 4 of those categories, so it can interact with Hibiscus Sabdariffa in 4 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIHYPERTENSIVE DRUGS

1 of 4

Why this applies to Trandolapril, Verapamil

Trandolapril, Verapamil falls under ANTIHYPERTENSIVE DRUGS — the group Hibiscus Sabdariffa interacts with.

Theoretically, taking Hibiscus sabdariffa with antihypertensive drugs might increase the risk of hypotension.
Most clinical evidence suggests that taking Hibiscus sabdariffa reduces systolic and diastolic blood pressure. In animal research, Hibiscus sabdariffa increased the hypotensive effects of single doses of losartan and amlodipine.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Tarka combines two blood pressure medicines: trandolapril (an ACE inhibitor) and verapamil (a calcium channel blocker). Both work to lower your blood pressure. Hibiscus, especially the tea, has a mild blood-pressure-lowering effect of its own. So the concern here is simple addition: hibiscus on top of Tarka may nudge your pressure down a little further than expected.

This is a theoretical concern based on how these things work, not strong human studies, so I wouldn't panic. Still, watch for signs your pressure dipped too low, like dizziness, lightheadedness when you stand, headache, or feeling tired. Occasional hibiscus tea is unlikely to be a problem, but concentrated supplements are stronger. If you'd like to use it regularly, check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McKay DL, Chen CY, Saltzman E, Blumberg JB. Hibiscus Sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adults. J Nutr 2010;140:298-303. PubMed
  2. Haji, Faraji M. and Haji, Tarkhani A. The effect of sour tea (Hibiscus sabdariffa) on essential hypertension. J.Ethnopharmacol. 1999;65(3):231-236. PubMed
  3. Mozaffari-Khosravi, H., Jalali-Khanabadi, B. A., Afkhami-Ardekani, M., Fatehi, F., and Noori-Shadkam, M. The effects of sour tea (Hibiscus sabdariffa) on hypertension in patients with type II diabetes. J Hum.Hypertens 2009;23(1):48-54. PubMed
  4. Ahad A, Raish M, Bin Jardan YA, Alam MA, Al-Mohizea AM, Al-Jenoobi FI. Effect of Hibiscus sabdariffa and Zingiber officinale on the antihypertensive activity and pharmacokinetic of losartan in hypertensive rats. Xenobiotica. 2020:1-11.
  5. Najafpour Boushehri S, Karimbeiki R, Ghasempour S, et al. The efficacy of sour tea (Hibiscus sabdariffa L.) on selected cardiovascular disease risk factors: A systematic review and meta-analysis of randomized clinical trials. Phytother Res. 2020;34(2):329
  6. Alam MA, Bin Jardan YA, Alzenaidy B, et al. Effect of Hibiscus sabdariffa and Zingiber officinale on pharmacokinetics and pharmacodynamics of amlodipine. J Pharm Pharmacol 2021;73(9):1151-60.
Minor

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

2 of 4

Trandolapril, Verapamil also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.

Theoretically, Hibiscus sabdariffa extract might reduce the metabolism of CYP1A2 substrates.
In vitro research shows that Hibiscus sabdariffa calyx extract inhibits CYP1A2. This interaction has not been reported in humans.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with Tarka (the trandolapril plus verapamil combo) and hibiscus. In lab dishes, hibiscus extract slows down a liver enzyme called CYP1A2. The thinking is that if it slows that enzyme, a drug cleared by it could build up a bit and push its effects harder. For this combo, both ingredients already lower blood pressure, so in theory you might see more dizziness, lightheadedness, a slower heart rate, or swelling in your ankles.

Now the honest part: this is purely theoretical, based on test-tube work, and it has not been seen in real people. A cup or two of hibiscus tea is unlikely to be a problem, but since hibiscus itself nudges blood pressure down too, just give your pharmacist or doctor a heads-up before using concentrated supplements.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Johnson SS, Oyelola FT, Ari T, Juho H. In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms. Afr J Tradit Complement Altern Med. 2013 Apr 12;10(3):533-40.
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

3 of 4

Trandolapril, Verapamil also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, Hibiscus sabdariffa extract might reduce the metabolism of CYP3A4 substrates.
In vitro research shows that Hibiscus sabdariffa calyx extract inhibits CYP3A4. This interaction has not been reported in humans.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Tarka pairs two blood pressure medicines: trandolapril (an ACE inhibitor) and verapamil (a calcium channel blocker). The verapamil part is handled by a liver enzyme called CYP3A4. In lab dishes, hibiscus extract appears to slow that same enzyme down a little. In theory, that could let verapamil build up slightly, which might add to its effects like a lower blood pressure, a slower heart rate, dizziness, swollen ankles, or constipation.

Here's the reassuring part: this is only a theoretical concern from test-tube work, and it has never actually been reported in people. A cup or two of hibiscus tea is unlikely to cause trouble, but since hibiscus also lowers blood pressure on its own, concentrated supplements deserve a quick check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Johnson SS, Oyelola FT, Ari T, Juho H. In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms. Afr J Tradit Complement Altern Med. 2013 Apr 12;10(3):533-40.
Minor

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES

4 of 4

Trandolapril, Verapamil also falls under CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES.

Theoretically, Hibiscus sabdariffa might reduce the metabolism of CYP2C8 substrates.
In vitro research shows that Hibiscus sabdariffa calyx extract inhibits CYP2C8. This interaction has not been reported in humans.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with Tarka, which combines trandolapril (a blood pressure pill) and verapamil (a calcium channel blocker). Lab studies suggest hibiscus may slow down an enzyme called CYP2C8. If that enzyme helps clear part of this combo, in theory the drug could linger a bit longer and its effects could be slightly amplified. With these medicines, that might show up as lower blood pressure than expected, dizziness, lightheadedness, a slower heart rate, or some ankle swelling.

That said, please don't worry too much. This is only seen in test-tube research, not in real people, and it's rated a minor interaction. A cup of tart hibiscus tea is unlikely to cause trouble, though concentrated supplements deserve more caution. Since hibiscus itself can nudge blood pressure down too, just give your pharmacist a heads-up before starting it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Johnson SS, Oyelola FT, Ari T, Juho H. In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms. Afr J Tradit Complement Altern Med. 2013 Apr 12;10(3):533-40.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Hibiscus Sabdariffa Also Interacts With Other Medications

Hibiscus Sabdariffa has 2 major, 265 moderate, 819 minor known drug interactions in our database — the Trandolapril, Verapamil one above is among them. If you take anything else, check it against the full list below.

Major 2 Moderate 265 Minor 819 No known interaction 1,744 (incl. Trandolapril, Verapamil)
Taking anything else?

Check Another of Your Medications Against Hibiscus Sabdariffa

Covers the 2,830 medications we’ve checked against Hibiscus Sabdariffa. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Trandolapril, Verapamil

This page covers Hibiscus Sabdariffa only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Trandolapril, Verapamil page lists 304 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Asarabacca (major) and Beer (major).

By severity: 11 major · 250 moderate · 43 minor.

From our pharmacist’s overview on the Trandolapril, Verapamil page

“This is one of the supplement lists I would want a patient to read closely, not skim. Tarka combines trandolapril and verapamil to lower blood pressure, and most of these interactions pull on that same lever, either dropping pressure further than intended or working against the medicine altogether.”

Reviewed by 2 · Jul 18, 2026

Open the Trandolapril, Verapamil interaction page

How much people look this up

Where Hibiscus Sabdariffa and Trandolapril, Verapamil Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Hibiscus Sabdariffa
Top half

#375 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Trandolapril, Verapamil
Top 25%

#514 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Hibiscus Sabdariffa

What is Hibiscus Sabdariffa?

Hibiscus Sabdariffa
  • High blood pressure
  • Heart and cholesterol health
  • Digestive upset
  • Antioxidant support
  • Fever and general wellness

Hibiscus sabdariffa is a tart, cranberry-flavored plant most often consumed as a tea, and its best-studied use is for mildly lowering blood pressure. Evidence for other uses is limited, and while hibiscus tea is generally well tolerated in food amounts, concentrated supplements should be used cautiously and avoided in pregnancy. Talk to your pharmacist or doctor before using it for a medical condition.

Read the full Hibiscus Sabdariffa monograph & all interactions
Keep checking

Other Drugs & Hibiscus Sabdariffa

Browse every other medication we’ve checked against Hibiscus Sabdariffa — both the ones with a known interaction and the ones without. Select any drug for the full detail.

2Major
265Moderate
819Minor
1,743No known interaction
2 Major 265 Moderate 819 Minor 1,743 No interaction
Major

2 interactions

Moderate

265 interactions

Showing 60 of 265 moderate interactions — see all 265 on the Hibiscus Sabdariffa page.

Minor

819 interactions

Showing 60 of 819 minor interactions — see all 819 on the Hibiscus Sabdariffa page.

No interaction 1,743 drugs checked — show the list

We also checked Hibiscus Sabdariffa against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,743 medications checked with no known interaction — see the full Hibiscus Sabdariffa list.

See the full Hibiscus Sabdariffa interactions page
See every supplement checked against Trandolapril, Verapamil, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Hibiscus Sabdariffa monograph › Uses, safety, and every drug interaction in one place Trandolapril, Verapamil supplement interactions › Every supplement checked against Trandolapril, Verapamil, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Hibiscus Sabdariffa and Trandolapril, Verapamil Together: Common Questions

Can you take Hibiscus Sabdariffa with Trandolapril, Verapamil?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 4 interactions listed for Hibiscus Sabdariffa and Trandolapril, Verapamil?
Trandolapril, Verapamil belongs to more than one drug category, and Hibiscus Sabdariffa interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Hibiscus Sabdariffa and Trandolapril, Verapamil interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Trandolapril, Verapamil and Hibiscus Sabdariffa?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.