Drug & supplement interaction

Blue Flag + Vadadustat

Vadadustat brand name: Vafseo.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Blue Flag and Vadadustat in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Blue Flag and Vadadustat

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Vadadustat and Blue Flag in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Blue Flag safety at a glance

Blue Flag overall Use caution The root, especially when fresh, can cause nausea, vomiting, and irritation, so it should be used cautiously.
Pregnancy Avoid Avoid during pregnancy because of potential toxicity and lack of safety data.
Breastfeeding Likely Unsafe When used orally; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Vadadustat and Blue Flag? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Vadadustat

Interactions in our licensed database are recorded against drug classes, not just single drug names. Vadadustat is filed under 5 classifications — including organic anion transporter 3 (oat3) substrates, organic anion transporter 1 (oat1) substrates, hepatotoxic drugs. Blue Flag has documented interactions with 3 drug classes — the most serious being digoxin (lanoxin) (major), diuretic drugs (moderate) and warfarin (coumadin) (moderate) — and none of Vadadustat’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Blue Flag Does Interact With Other Medications

Blue Flag has 1 major, 77 moderate known drug interactions in our database — Vadadustat isn’t one of them. If you take anything else, check it against the full list below.

Major 1 Moderate 77 No known interaction 2,752 (incl. Vadadustat)
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.

What to actually watch for

What Blue Flag Itself Has Been Linked To

This is not an interaction — nothing below involves Vadadustat. It is the side-effect record for Blue Flag on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Blue Flag, this list is the first place to look.

  • Vomiting / Nausea Additional detail

    “Orally, blue flag can cause nausea and vomiting, and the fresh root can irritate mucosa (4,19). Orally and topically, the volatile oil constituent of blue flag irritates mucous membranes and can cause lacrimation, eye inflammation, irritation of the throat, and headache (4).”

    Blue Flag · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
    2. 19. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

    “Orally, blue flag can cause nausea and vomiting and the fresh blue flag root can irritate mucosa (4,19). The volatile oil constituent of blue flag irritates mucous membranes and can cause irritation of the throat (4).”

    Blue Flag · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    2 sources cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
    2. 19. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  • Headache Additional detail

    “Orally, the volatile oil constituent of blue flag can cause headache (4).”

    Blue Flag · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.

Everything above comes from the Natural Medicines adverse-effect record for Blue Flag — expand a row for the licensed statement it rests on. We haven’t matched Vadadustat to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Vadadustat.

Special populations

Blue Flag in Pregnancy & Breastfeeding

Lactation Likely Unsafe

When used orally; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Everything else you take

See Every Supplement That Interacts With Vadadustat

This page covers Blue Flag only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Vadadustat page lists 65 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and African Wild Potato (moderate).

By severity: 4 major · 52 moderate · 9 minor.

From our pharmacist’s overview on the Vadadustat page

“Most people taking vadadustat (Vafseo) are treating anemia from chronic kidney disease, and this particular list warrants genuine care. Of the 65 supplements and herbs with a documented interaction, 4 are rated major, and the dominant theme is liver strain: 38 of these ingredients can injure the liver on their own, a real concern since…”

Reviewed by 2 · Jul 18, 2026

Open the Vadadustat 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. Even though Blue Flag itself has no known interaction with Vadadustat, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Blue Flag and Vadadustat 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

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

29 days ago today
Medication Vadadustat
Top half

#1,316 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Blue Flag reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Blue Flag and Vadadustat records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
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.

Iris versicolor · Iridaceae · Dried rhizome (root) · Dried root, tincture, liquid extract, capsules, occasionally in topical preparations

An interaction check asks whether these two react with each other — it does not ask whether Blue Flag is a good idea for someone in your situation. Here is what our Blue Flag record says about it on its own.

Blue Flag: dosing

There is no well-established or standardized dose for Blue Flag, and reliable dosing information from quality clinical research is lacking. Traditional sources used small amounts of the dried root or tincture, but these are not validated by modern studies.If a product is used, follow the directions on the label and start low.

From our Blue Flag monograph — the full record covers uses, side effects and every documented interaction.

Read the full Blue Flag monograph & all interactions
Medication

About Vadadustat

Most-Reported Side Effects for Vadadustat

From FAERS, the FDA’s public side-effect reporting system (284 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 25 reports
Haemoglobin decreased 16 reports
Marasmus 14 reports
Cardiac failure 13 reports
Nausea 11 reports
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
77Moderate
0Minor
2,751No known interaction
1 Major 77 Moderate 2,751 No interaction
Major

1 interaction

Moderate

77 interactions

Showing 60 of 77 moderate interactions — see all 77 on the Blue Flag page.

No interaction 2,751 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 2,751 medications checked with no known interaction — see the full Blue Flag list.

See the full Blue Flag interactions page
See every supplement checked against Vadadustat, ranked by severity
Evidence & sources

Blue Flag References

The 3 references that drive our Blue Flag monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  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.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Blue Flag and Vadadustat Together: Common Questions

Is it safe to take Blue Flag with Vadadustat?
We do not list a known interaction between Blue Flag and Vadadustat. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Blue Flag and Vadadustat combination checked?
Interactions in our licensed database are recorded against drug classes. Vadadustat is filed under 5 classifications, and Blue Flag has documented interactions with 3 drug classes — none of Vadadustat's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Blue Flag interact with any other medications?
Yes. Blue Flag has 78 documented drug interactions in our database — Vadadustat is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Vadadustat interact with any supplements?
Yes. Vadadustat has documented interactions with 65 supplements in our database — Blue Flag is not one of them. The Vadadustat interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Blue Flag monograph Uses, safety profile, and every drug interaction in one place Vadadustat supplement interactions Every supplement checked against Vadadustat, 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 References The 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Vadadustat and Blue Flag?

Our pharmacists answer your medication & supplement questions — free.

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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.