Major interaction on record — check this product against your medications before combining. Check your meds →
Dietary supplement

Blue Flag Ingredients & Drug Interactions

by Herb Pharm

Blue Flag label
See full label image
Liquid Category: Botanical
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Blue Flag against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Blue Flag is a dietary supplement by Herb Pharm with 1 active ingredient. Its ingredients are commonly taken for skin conditions like acne and eczema, constipation and digestive complaints, liver and gallbladder support (traditional).Based on those ingredients, 78 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Blue Flag liquid extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Blue Flag by Herb Pharm

Ask about any prescription or over-the-counter medication and we check it for interactions with Blue Flag by Herb Pharm — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Blue Flag by Herb Pharm

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 0 of its 1 active ingredient.

Blue Flag by Herb Pharm is a liquid extract containing one active ingredient: blue flag root extract. The product also contains certified organic grain alcohol and blue flag extractives as inactive ingredients.

Does it work?

Couldn't assess
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

This is a single-ingredient Blue Flag product and its label doesn't state a use — see Blue Flag's own graded uses on its monograph.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

The effectiveness of blue flag has not been established in the data we hold.

The evidence, ingredient by ingredient Blue Flag

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Blue flag can cause nausea, vomiting, and irritation of the mouth and throat, especially when the fresh root is used. The volatile oil in blue flag can also irritate mucous membranes and cause eye inflammation, throat irritation, and headache.

Blue flag is not safe during pregnancy because of potential toxicity and lack of safety data. It's also not safe while breastfeeding due to insufficient safety information.

If you're pregnant or nursing, don't use this product without talking to your doctor or pharmacist first.

Side effects, ingredient by ingredient Blue Flag

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Blue Flag.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; heart-rhythm medications.
  • For scale: 78 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check with your pharmacist before using blue flag if you take digoxin (a heart medication)—that's a Major interaction. Also double-check if you take diuretics (water pills) or warfarin (a blood thinner), both Moderate concerns.

Altogether, these interactions span 78 individual medications, so use the search tool on this page for your prescriptions.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with no assessable stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Blue flag is best avoided if you take digoxin, diuretics, or warfarin—the interactions can be serious. Even if you don't take those drugs, expect possible nausea, vomiting, and throat irritation.

Skip it entirely if you're pregnant or breastfeeding. Always check your exact medications with your pharmacist before starting.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated May 23, 2014.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Blue Flag, straight from the product label.

Brand Herb Pharm
Barcode (UPC) 090700000172
Net contents 1 fl. Oz.; 29.6 mL
Market status On market
Date entered into DSLD May 23, 2014
DSLD ID 32932
Product type Botanical
Supplement form Liquid
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Blue Flag by Herb Pharm, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
5 Drop(s)
Maximum serving Sizes:
15 Drop(s)
UPC/BARCODE
090700000172
IngredientAmount% DV
Blue Flag liquid extract0 NP--

Other ingredients: certified organic grain Alcohol, Blue Flag extractives

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
General Statements

LIQUID HERBAL EXTRACT

To assure optimal extraction of Blue Flag's bioactive compounds, the rhizome (with roots) is hand-harvested in late autumn or early spring and is then taken directly to our laboratory and promptly extracted while still fresh and succulent.

FDA Statement of Identity

HERBAL SUPPLEMENT

Suggested/Recommended/Usage/Directions

SUGGESTED USE Shake Well Before Using One to three times per day take 5 to 15 drops in a cup of water.

Precautions

Caution: Do not take drops undiluted.

Do not give to children younger than 12 years old.

Do not take if pregnant or nursing, or in cases of stomach or intestinal irritation, or diarrhea.

Should not be taken longer than two weeks.

Keep Out of the Reach of Children

Brand IP Statement(s)

We prepare our Blue Flag Extract from the fresh (undried) rhizome & roots of Iris versicolor plants which are Custom Wildcrafted(TM) in their natural wild habitat.

General

004

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Blue Flag by Herb Pharm label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Blue Flag label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Blue Flag by Herb Pharm

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size5 Drop(s) Dosage formLiquid Amounts shown are per serving.

Blue Flag liquid extract

Interacts with
78 drugs
0 NP per serving

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...

Blue Flag liquid extract monograph & interactions

Other (inactive) ingredients: Certified organic grain Alcohol, Blue Flag extractives. These complete the product’s ingredient list but are not active constituents.

Interaction report

Blue Flag by Herb Pharm Drug Interactions

Want to check YOUR meds against Blue Flag?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
78Drugs
1 Major 77 Moderate

Ingredients driving the most interactions

Blue Flag liquid extract 78

Individual Drug Interactions

The ingredients in Blue Flag interact with 78 drugs. Click any drug to see the details.

1 of the 1 ingredient in Blue Flag interact with drugs. Each result below shows which ingredient is responsible. Blue Flag liquid extract

Each ingredient & the kinds of drugs it affects

For each ingredient in Blue Flag with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Blue Flag liquid extract3 drug types · 78 drugs

Digoxin (Lanoxin)

Theoretically, overuse or abuse of this product increases the risk of adverse effects from cardiac glycoside drugs.

Likelihood Probable Evidence D
Diuretic Drugs

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.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Blue flag has stimulant laxative effects. In some people blue flag can cause diarrhea. Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding. Advise patients who take warfarin not to take excessive amounts of blue flag.

Likelihood Possible Evidence D
Blue Flag liquid extract full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Blue Flag, from the product label.

Herb Pharm

See all Herb Pharm products
Name
Herb Pharm
City
Williams
State
OR
ZipCode
97544
Phone Number
800-348-4372
Web Address
www.herb-pharm.com
Pharmacist Counseling Corner

Blue Flag by Herb Pharm: Common Questions

Does Blue Flag by Herb Pharm interact with any medications?
Yes. Based on its ingredients, Blue Flag has a known interaction with 78 medications, including 1 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Blue Flag contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Can I take blue flag if I'm pregnant?
No. Blue flag should be avoided during pregnancy because of potential toxicity and lack of safety data. Talk to your doctor or pharmacist before using it.
Is blue flag safe while breastfeeding?
No. There isn't enough safety information to recommend blue flag while breastfeeding. Avoid it and check with your pharmacist or doctor for alternatives.
What side effects can blue flag cause?
Blue flag commonly causes nausea and vomiting. It can also irritate your mouth, throat, and eyes, and trigger headaches—especially the fresh root and its volatile oil are irritating.
Why is blue flag a concern with warfarin?
Blue flag acts as a stimulant laxative and can cause diarrhea. Diarrhea makes warfarin work stronger, raises your INR (your clotting measure), and increases your bleeding risk. Avoid excessive amounts if you take warfarin.
Can I use blue flag with my water pill?
Be cautious. Blue flag may worsen the potassium loss that diuretics cause, raising your risk of low potassium. Your doctor may need to adjust your potassium supplement dose. Check with your pharmacist first.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Blue Flag label
Go deeper

The Full Monographs Behind Blue Flag’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Blue Flag

Interacts with 78 drugs

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 t...

Read the full Blue Flag monograph →
Sources

Sources & How We Checked

Blue Flag's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 3 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Blue Flag 3 references
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  3. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

See these in context on the Blue Flag monograph →

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

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