Drug & supplement interaction

Blue Flag + Polythiazide, Reserpine

Polythiazide, Reserpine brand name: Renese R.

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

Blue Flag has a moderate interaction with Polythiazide, Reserpine. Overuse of blue flag might compound diuretic-induced potassium loss.

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

Blue Flag and Polythiazide, Reserpine

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

Moderate

DIURETIC DRUGS

Why this applies to Polythiazide, Reserpine

Polythiazide, Reserpine falls under DIURETIC DRUGS — the group Blue Flag interacts with.

Overuse of blue flag might compound diuretic-induced potassium loss. There is some concern that people taking blue flag along with potassium depleting diuretics might have an increased risk for hypokalemia. Initiation of potassium supplementation or an increase in potassium supplement dose may be necessary for some patients. Some diuretics that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, Hydrodiuril, Microzide), 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

Your Renese R combines two medicines, and the part that matters here is polythiazide, a water pill (thiazide diuretic). One thing thiazides are known for is lowering your body's potassium over time. Blue Flag root has been used traditionally as a laxative, and if it gets you running to the bathroom a lot, that fluid and mineral loss could stack on top of what the diuretic is already doing and push your potassium down further.

Keep in mind this is a theoretical concern based on how these things work, not strong human studies. Still, low potassium can cause muscle cramps, weakness, tiredness, or an irregular heartbeat. Occasional food amounts are unlikely to matter, but regular Blue Flag supplements could. Please check with your pharmacist or doctor before combining them, and don't change anything on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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

Blue Flag Also Interacts With Other Medications

Blue Flag has 1 major, 76 moderate known drug interactions in our database — the Polythiazide, Reserpine one above is one of them. If you take anything else, check it against the full list below.

Major 1 Moderate 76 No known interaction 2,753 (incl. Polythiazide, Reserpine)
Taking anything else?

Check Another of Your Medications Against Blue Flag

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

Everything else you take

See Every Supplement That Interacts With Polythiazide, Reserpine

This page covers Blue Flag only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Polythiazide, Reserpine page lists 228 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 · 193 moderate · 25 minor.

From our pharmacist’s overview on the Polythiazide, Reserpine page

“American hellebore is the ingredient I would keep farthest from polythiazide with reserpine (Renese R), a combination pill prescribed to lower blood pressure. Its alkaloids can drop pressure and slow the heart even at small doses, and it is one of ten major-rated entries among the 228 on file here, which puts this list in the take-it-s…”

Reviewed by 2 · Jul 18, 2026

Open the Polythiazide, Reserpine interaction page

One more smart check

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

We hold 101 real supplement products containing Blue Flag, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Blue Flag. Your product may carry other ingredients that interact with Polythiazide, Reserpine too, on top of Blue Flag — 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 Blue Flag and Polythiazide, Reserpine 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 Blue Flag
Steady interest

#1,192 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Polythiazide, Reserpine
Steady interest

#2,396 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 Blue Flag

What is Blue Flag?

  • Skin conditions like acne and eczema
  • Constipation and digestive complaints
  • Liver and gallbladder support (traditional)
  • Lymphatic and 'detox' tonic (traditional)
  • Thyroid and glandular swelling (traditional)

Blue Flag is a flowering plant whose root has been used in traditional and herbal medicine for skin and digestive complaints, but there is very little modern scientific evidence to support these uses. The fresh root can be toxic and irritating, so it should be used cautiously, if at all, and avoided in pregnancy and breastfeeding. Talk to a pharmacist or doctor before trying it.

Read the full Blue Flag monograph & all interactions
Keep checking

Other Drugs & Blue Flag

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

1Major
76Moderate
0Minor
2,752No known interaction
1 Major 76 Moderate 2,752 No interaction
Major

1 interaction

Moderate

76 interactions

Showing 60 of 76 moderate interactions — see all 76 on the Blue Flag page.

No interaction 2,752 drugs checked — show the list

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

Showing the 60 most looked-up of 2,752 medications checked with no known interaction — see the full Blue Flag list.

See the full Blue Flag interactions page
See every supplement checked against Polythiazide, Reserpine, 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
Blue Flag monograph › Uses, safety, and every drug interaction in one place Polythiazide, Reserpine supplement interactions › Every supplement checked against Polythiazide, Reserpine, 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 Blue Flag and Polythiazide, Reserpine Together: Common Questions

Can you take Blue Flag with Polythiazide, Reserpine?
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 Blue Flag and Polythiazide, Reserpine 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 Polythiazide, Reserpine and Blue Flag?

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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.