Drug & supplement interaction

Bridelia + Guanethidine Monosulfate

Guanethidine Monosulfate brand names: Ismelin, Isimil.

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

Bridelia has a moderate interaction with Guanethidine Monosulfate. Animal research suggests that Bridelia extracts decrease arterial pressure.

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

Bridelia and Guanethidine Monosulfate

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Guanethidine Monosulfate

Guanethidine Monosulfate falls under ANTIHYPERTENSIVE DRUGS — the group Bridelia interacts with.

Animal research suggests that Bridelia extracts decrease arterial pressure. Theoretically, concomitant use of Bridelia with antihypertensive drugs might have additive blood pressure lowering effects.
Some antihypertensive drugs include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), and others.
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

Here's the simple version: guanethidine is a strong blood pressure lowering medicine. In animal studies, Bridelia extracts also nudged blood pressure down. So if you put the two together, the worry is that they could stack up and drop your pressure more than expected.

If that happens, you might notice dizziness, lightheadedness, or feeling faint when you stand up (guanethidine is already known for this kind of standing-up drop). I want to be honest, though: this is a theoretical concern based on lab and animal work, not proven in people. Still, since guanethidine is so potent, I'd play it safe. Please check with your pharmacist or doctor before pairing them, and don't change your medicine on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Corallo A, Foungbe S, Davy M, Cohen Y. Cardiovascular pharmacology of aqueous extract of the leaves of Bridelia atroviridis Muell. Arg. (Euphorbiaceae) in the rat. J Ethnopharmacol 1997;57(3):189-96. PubMed

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

Bridelia Also Interacts With Other Medications

Bridelia has 329 moderate known drug interactions in our database — the Guanethidine Monosulfate one above is one of them. If you take anything else, check it against the full list below.

Moderate 329 No known interaction 2,501 (incl. Guanethidine Monosulfate)
Taking anything else?

Check Another of Your Medications Against Bridelia

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

Everything else you take

See Every Supplement That Interacts With Guanethidine Monosulfate

This page covers Bridelia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Guanethidine Monosulfate page lists 137 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), Tyramine (major) and Adrafinil (moderate).

By severity: 4 major · 112 moderate · 21 minor.

From our pharmacist’s overview on the Guanethidine Monosulfate page

“Guanethidine monosulfate (Ismelin) is a forceful older drug for severe high blood pressure, and its interaction list warrants genuine care. Nearly all 137 supplements and herbs on file pull blood pressure one way or the other, either adding to the drug's effect and risking dizziness and faints, or pushing pressure back up and undoing t…”

Reviewed by 2 · Jul 18, 2026

Open the Guanethidine Monosulfate interaction page

How much people look this up

Where Bridelia and Guanethidine Monosulfate 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 Bridelia
Steady interest

#1,311 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Guanethidine Monosulfate
Steady interest

#1,649 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 Bridelia

What is Bridelia?

  • Blood sugar support
  • Digestive complaints and diarrhea
  • Wound care and skin conditions
  • Antimicrobial use
  • Mouth and gum care (traditional chewing stick)

Bridelia is a group of tropical plants, with Bridelia ferruginea widely used in traditional African medicine for diabetes, infections, and digestive problems. Scientific evidence is mostly limited to laboratory and animal studies, so its benefits and safety in people are not well established. Talk to a pharmacist or doctor before using it, especially if you take other medicines or have a health condition.

Read the full Bridelia monograph & all interactions
Keep checking

Other Drugs & Bridelia

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

0Major
329Moderate
0Minor
2,500No known interaction
329 Moderate 2,500 No interaction
Moderate

329 interactions

Showing 60 of 329 moderate interactions — see all 329 on the Bridelia page.

No interaction 2,500 drugs checked — show the list

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

Showing the 60 most looked-up of 2,500 medications checked with no known interaction — see the full Bridelia list.

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

Can you take Bridelia with Guanethidine Monosulfate?
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 Bridelia and Guanethidine Monosulfate 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 Guanethidine Monosulfate and Bridelia?

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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.