Drug & supplement interaction

Periwinkle + Hydrochlorothiazide, Labetalol

Hydrochlorothiazide, Labetalol brand name: Trandate HCT.

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

Periwinkle has a moderate interaction with Hydrochlorothiazide, Labetalol. Theoretically, taking periwinkle may increase the effects of antihypertensive drugs due to the hypotensive activity of vincamine, a constituent of periwinkle.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Periwinkle and Hydrochlorothiazide, Labetalol

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Hydrochlorothiazide, Labetalol

Hydrochlorothiazide, Labetalol falls under ANTIHYPERTENSIVE DRUGS — the group Periwinkle interacts with.

Theoretically, taking periwinkle may increase the effects of antihypertensive drugs due to the hypotensive activity of vincamine, a constituent of periwinkle.
Severity Moderate Likelihood Probable Evidence D

Interaction 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..

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

Your combination pill pairs labetalol (which relaxes blood vessels and slows the heart) with hydrochlorothiazide (a water pill that lowers blood pressure). Both already work to bring your numbers down. Periwinkle contains a compound called vincamine that may, on its own, lower blood pressure a little too. So the worry here is simply that they could add up.

I'll be honest with you: this is a theoretical concern based on how vincamine behaves, not on solid human studies. Still, if the effects stacked, you might feel dizzy, lightheaded, tired, or faint, especially when standing up quickly. Please don't change anything on your own. Just check with your pharmacist or doctor before adding periwinkle, and keep an eye on your blood pressure if you do.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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

Periwinkle Also Interacts With Other Medications

Periwinkle has 171 moderate known drug interactions in our database — the Hydrochlorothiazide, Labetalol one above is one of them. If you take anything else, check it against the full list below.

Moderate 171 No known interaction 2,659 (incl. Hydrochlorothiazide, Labetalol)
Taking anything else?

Check Another of Your Medications Against Periwinkle

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

Everything else you take

See Every Supplement That Interacts With Hydrochlorothiazide, Labetalol

This page covers Periwinkle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydrochlorothiazide, Labetalol page lists 265 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: 13 major · 228 moderate · 24 minor.

From our pharmacist’s overview on the Hydrochlorothiazide, Labetalol page

“Most people on Trandate HCT (hydrochlorothiazide with labetalol) are treating blood pressure for the long haul, often alongside calcium for bones or herbal wellness products, and that overlap is exactly where this list turns serious. Most of its 265 interacting ingredients either lower blood pressure beyond what was intended or pile on…”

Reviewed by 2 · Jul 18, 2026

Open the Hydrochlorothiazide, Labetalol interaction page

One more smart check

Taking Periwinkle as Part of a Dietary Supplement Product? Check It for Interactions

We hold 38 real supplement products containing Periwinkle, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Periwinkle. Your product may carry other ingredients that interact with Hydrochlorothiazide, Labetalol too, on top of Periwinkle — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Periwinkle and Hydrochlorothiazide, Labetalol 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 Periwinkle
Top half

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

29 days ago today
Medication Hydrochlorothiazide, Labetalol
Top 25%

#476 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 Periwinkle

What is Periwinkle?

  • Memory and cognitive support
  • Circulation problems
  • Dizziness and ringing in the ears
  • Minor wounds and sore throat (traditional)
  • High blood pressure (traditional)

Periwinkle (Vinca minor) is a flowering plant whose alkaloids are the source of vinpocetine, a compound marketed for memory and brain circulation. Evidence in humans is limited and mixed, and the plant contains potent compounds that can be toxic in larger amounts, so it should be used only with professional guidance. A closely related plant, Madagascar periwinkle, is the source of important cancer chemotherapy drugs but is not safe to use as a home remedy.

Read the full Periwinkle monograph & all interactions
Keep checking

Other Drugs & Periwinkle

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

0Major
171Moderate
0Minor
2,658No known interaction
171 Moderate 2,658 No interaction
Moderate

171 interactions

Showing 60 of 171 moderate interactions — see all 171 on the Periwinkle page.

No interaction 2,658 drugs checked — show the list

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

Showing the 60 most looked-up of 2,658 medications checked with no known interaction — see the full Periwinkle list.

See the full Periwinkle interactions page
See every supplement checked against Hydrochlorothiazide, Labetalol, 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
Periwinkle monograph › Uses, safety, and every drug interaction in one place Hydrochlorothiazide, Labetalol supplement interactions › Every supplement checked against Hydrochlorothiazide, Labetalol, 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 Periwinkle and Hydrochlorothiazide, Labetalol Together: Common Questions

Can you take Periwinkle with Hydrochlorothiazide, Labetalol?
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.
How serious is the Periwinkle and Hydrochlorothiazide, Labetalol 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 Hydrochlorothiazide, Labetalol and Periwinkle?

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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.