Drug & supplement interaction

Echinacea + Grepafloxacin

Grepafloxacin brand name: Raxar.

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

Echinacea has a moderate interaction with Grepafloxacin. Echinacea might inhibit the metabolism of CYP1A2 and increase plasma levels of some drugs.

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

Echinacea and Grepafloxacin

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

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Why this applies to Grepafloxacin

Grepafloxacin falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Echinacea interacts with.

Echinacea might inhibit the metabolism of CYP1A2 and increase plasma levels of some drugs.
Echinacea appears to inhibit CYP1A2 enzymes in humans. Additionally, echinacea seems to increase plasma concentrations of caffeine, a CYP1A2 substrate, by around 30%. Theoretically, echinacea might increase levels of other drugs metabolized by CYP1A2.
Severity Moderate Likelihood Possible Evidence B

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

Grepafloxacin is an antibiotic that your liver partly clears using an enzyme called CYP1A2. Echinacea seems to slow that same enzyme down. So the concern here is that taking echinacea alongside grepafloxacin could let the antibiotic build up a bit more than usual in your blood, which can mean stronger side effects.

With grepafloxacin specifically, that matters because this drug was already known for affecting heart rhythm (a QT-prolonging effect), along with the usual nausea, dizziness, or headache. Higher levels could nudge those risks up. The evidence is modest and partly based on a caffeine study showing about a 30% rise, so it is a real but not dramatic concern. Please run this combination by your pharmacist or doctor before mixing them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gorski JC, Huang S, Zaheer NA, et al. The effect of echinacea (Echinacea purpurea root) on cytochrome P450 activity in vivo.Clin Pharmacol Ther 2003;73 (Abstract PDII-A-8):P94. 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

Echinacea Also Interacts With Other Medications

Echinacea has 814 moderate, 1 minor known drug interactions in our database — the Grepafloxacin one above is one of them. If you take anything else, check it against the full list below.

Moderate 814 Minor 1 No known interaction 2,015 (incl. Grepafloxacin)
Taking anything else?

Check Another of Your Medications Against Echinacea

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

From our Q&A

Questions About Echinacea or Grepafloxacin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Echinacea or Grepafloxacin, 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 Grepafloxacin

This page covers Echinacea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Grepafloxacin page lists 164 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Apple (major), Arsenic (major) and Cesium (major).

By severity: 9 major · 113 moderate · 42 minor.

From our pharmacist’s overview on the Grepafloxacin page

“A week on grepafloxacin (Raxar), a quinolone antibiotic, often comes with juice at breakfast, coffee through the day, maybe a probiotic for the stomach, and each of those shows up on this list. The nine major entries among these 164 deserve your attention first: grapefruit and other fruit juices can block the transporter that carries t…”

Reviewed by 2 · Jul 18, 2026

Open the Grepafloxacin interaction page

One more smart check

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

We hold 350 real supplement products containing Echinacea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Echinacea. Your product may carry other ingredients that interact with Grepafloxacin too, on top of Echinacea — 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 Echinacea and Grepafloxacin 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 Echinacea
Top 5%

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

29 days ago today
Medication Grepafloxacin
Steady interest

#2,311 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 Echinacea

What is Echinacea?

Echinacea
  • Common cold
  • Flu and respiratory infections
  • Immune support
  • Sore throat
  • Wound and skin care (traditional)

Echinacea is a popular herb taken to help prevent or shorten the common cold, but study results are mixed and the overall benefit appears small at best. It is generally well tolerated for short-term use in most healthy adults, though people with allergies to daisy-family plants and those who are pregnant or breastfeeding should be cautious and talk to a pharmacist or doctor first.

Read the full Echinacea monograph & all interactions
Keep checking

Other Drugs & Echinacea

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

0Major
814Moderate
1Minor
2,014No known interaction
814 Moderate 1 Minor 2,014 No interaction
Moderate

814 interactions

Showing 60 of 814 moderate interactions — see all 814 on the Echinacea page.

Minor

1 interaction

No interaction 2,014 drugs checked — show the list

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

Showing the 60 most looked-up of 2,014 medications checked with no known interaction — see the full Echinacea list.

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

Can you take Echinacea with Grepafloxacin?
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 Echinacea and Grepafloxacin 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 Grepafloxacin and Echinacea?

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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.