Drug & supplement interaction

Blue Flag + Spironolactone

Spironolactone brand names: Aldactone, Spiroton, Carospir.

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

Blue Flag has a moderate interaction with Spironolactone. 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 Spironolactone

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

Moderate

DIURETIC DRUGS

Why this applies to Spironolactone

Spironolactone 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

Here's a twist worth knowing about. The interaction on file warns that Blue Flag, used in large amounts, may act like a laxative and could cause the body to lose potassium. But Spironolactone is different from most diuretics. It's a 'potassium-sparing' water pill, meaning it actually helps your body hold onto potassium rather than dump it. So the usual concern of low potassium doesn't really line up neatly with this particular medication.

That said, this warning is theoretical, based on how these substances behave in the body rather than solid studies. Real-world worry with spironolactone is usually the opposite (potassium climbing too high). Heavy Blue Flag use can also irritate your gut and cause diarrhea, which throws off fluids and minerals. Please check with your pharmacist or doctor before combining them.

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 Spironolactone 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. Spironolactone)
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.

From our Q&A

Questions About Blue Flag or Spironolactone

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Blue Flag or Spironolactone, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Spironolactone

This page covers Blue Flag only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Spironolactone page lists 206 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), Lithium (major) and Oleander (major).

By severity: 7 major · 174 moderate · 25 minor.

From our pharmacist’s overview on the Spironolactone page

“Potassium is the supplement I check first for anyone on spironolactone (Aldactone, Carospir), because this water pill works by holding potassium in the body, and supplementing more on top of that can push blood levels too high. It is one of 206 supplement and herbal ingredients with documented interactions here, and the list warrants g…”

Reviewed by 2 · Jul 18, 2026

Open the Spironolactone 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 Spironolactone 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 Spironolactone 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
Top half

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

29 days ago today
Medication Spironolactone
Top 10%

#155 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
Medication

About Spironolactone

What Is Spironolactone Used For?

Brand names: Aldactone, Spiroton, Carospir

Spironolactone tablets and spironolactone oral suspension are used to treat several conditions. Both forms treat NYHA Class III–IV heart failure with reduced ejection fraction — helping patients survive longer, reducing fluid buildup, and lowering the need for hospitalization. Both are also used as add-on therapy for high blood pressure when other medicines aren't enough, and to manage fluid buildup (edema) in adults with liver cirrhosis.

Spironolactone tablets (including Aldactone) are additionally approved to manage edema in nephrotic syndrome (a kidney disorder causing protein loss and swelling) and to treat primary hyperaldosteronism — a condition where the adrenal glands overproduce the hormone aldosterone — both before surgery and as long-term therapy for patients who can't or won't have surgery. The oral suspension is not approved for nephrotic syndrome or primary hyperaldosteronism.

See full Spironolactone drug information
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 Spironolactone, 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 Spironolactone supplement interactions › Every supplement checked against Spironolactone, ranked by severity Spironolactone drug information › The full plain-English guide to this medication 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 Spironolactone Together: Common Questions

Can you take Blue Flag with Spironolactone?
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 Spironolactone 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 Spironolactone 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.