Drug & supplement interaction

Gentian + Guanethidine, Hydrochlorothiazide

Guanethidine, Hydrochlorothiazide brand name: Esimil.

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

Gentian has a moderate interaction with Guanethidine, Hydrochlorothiazide. Theoretically, taking gentian with antihypertensive drugs might increase the risk of hypotension.

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

Gentian and Guanethidine, Hydrochlorothiazide

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Guanethidine, Hydrochlorothiazide

Guanethidine, Hydrochlorothiazide falls under ANTIHYPERTENSIVE DRUGS — the group Gentian interacts with.

Theoretically, taking gentian with antihypertensive drugs might increase the risk of hypotension.
In vitro research shows that gentian can cause vasodilation and lower blood pressure.
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

Esimil combines guanethidine and hydrochlorothiazide, and both of these work to lower your blood pressure. The thought here is pretty simple: lab studies suggest gentian can relax blood vessels and nudge blood pressure down a little on its own. Stack that gentle effect on top of a medicine that's already designed to drop your pressure, and in theory the two could add up.

If your pressure dipped too low, you might feel dizzy, lightheaded, or faint, especially when standing up quickly, which guanethidine is already known to cause. That said, this is only a theoretical concern based on test-tube research, not real patient reports, and small culinary amounts of bitters are unlikely to matter. Still, mention it to your pharmacist or doctor before starting gentian.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Uncini Manganelli RE, Chericoni S, Baragatti B. Ethnopharmacobotany in Tuscany: plants used as antihypertensives. Fitoterapia 2000;71:S95-100. PubMed
  2. Baragatti B, Calderone V, Testai L, et al. Vasodilator activity of crude methanolic extract of Gentiana kokiana Perr. et Song. (Gentianaceae). J Ethnopharmacol 2002;79:369-72. 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

Gentian Also Interacts With Other Medications

Gentian has 171 moderate known drug interactions in our database — the Guanethidine, Hydrochlorothiazide 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. Guanethidine, Hydrochlorothiazide)
Taking anything else?

Check Another of Your Medications Against Gentian

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

Everything else you take

See Every Supplement That Interacts With Guanethidine, Hydrochlorothiazide

This page covers Gentian only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Guanethidine, Hydrochlorothiazide page lists 231 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 Dolomite (major).

By severity: 10 major · 196 moderate · 25 minor.

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

“Guanethidine with hydrochlorothiazide (Esimil) lowers blood pressure two ways at once, and 231 supplement and herbal ingredients on file can interfere with it, ten rated major and just 25 minor, so treat this page with genuine care. Most of the 196 moderate entries pile extra blood-pressure-lowering on top of the drug, and a second lar…”

Reviewed by 2 · Jul 18, 2026

Open the Guanethidine, Hydrochlorothiazide interaction page

One more smart check

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

We hold 749 real supplement products containing Gentian, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Gentian. Your product may carry other ingredients that interact with Guanethidine, Hydrochlorothiazide too, on top of Gentian — 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 Gentian and Guanethidine, Hydrochlorothiazide 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 Gentian
Top 25%

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

29 days ago today
Medication Guanethidine, Hydrochlorothiazide
Steady interest

#1,583 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 Gentian

What is Gentian?

  • Loss of appetite
  • Indigestion and bloating
  • Digestive bitter tonic
  • Stomach upset
  • Sluggish digestion

Gentian is a very bitter root traditionally used to stimulate appetite and ease mild digestive complaints, often as part of "bitters" before meals. The evidence is mostly traditional and preliminary, and while short-term use of normal amounts appears generally well tolerated in healthy adults, anyone with ulcers, reflux, or who is pregnant should be cautious and check with a pharmacist or doctor first.

Read the full Gentian monograph & all interactions
Keep checking

Other Drugs & Gentian

Browse every other medication we’ve checked against Gentian — 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 Gentian page.

No interaction 2,658 drugs checked — show the list

We also checked Gentian 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 Gentian list.

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

Can you take Gentian with Guanethidine, Hydrochlorothiazide?
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 Gentian and Guanethidine, Hydrochlorothiazide 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, Hydrochlorothiazide and Gentian?

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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.