Drug & supplement interaction

Eleuthero + Fexofenadine, Pseudoephedrine

Fexofenadine, Pseudoephedrine brand name: Allegra D.

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

Fexofenadine, Pseudoephedrine falls into 3 drug categories that Eleuthero can interact with; the most serious is rated moderate. Theoretically, eleuthero might increase levels of P-glycoprotein substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Eleuthero and Fexofenadine, Pseudoephedrine

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Eleuthero interacts with whole categories of medication. Fexofenadine, Pseudoephedrine falls into 3 of those categories, so it can interact with Eleuthero in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

P-GLYCOPROTEIN SUBSTRATES

1 of 3

Why this applies to Fexofenadine, Pseudoephedrine

Fexofenadine, Pseudoephedrine falls under P-GLYCOPROTEIN SUBSTRATES — the group Eleuthero interacts with.

Theoretically, eleuthero might increase levels of P-glycoprotein substrates.
In vitro research suggests that eleuthero can inhibit the multi-drug transporter protein, P-glycoprotein. However, it is too soon to tell if this is clinically important. This interaction has not been reported in humans.
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 the gist with Allegra-D and eleuthero. The fexofenadine part of your Allegra-D is carried in and out of your body by a transporter called P-glycoprotein. In lab dishes, eleuthero seems to slow that transporter down, which could let a bit more fexofenadine hang around. In theory that might mean slightly stronger antihistamine effects, like more drowsiness or dry mouth, though fexofenadine is usually pretty gentle on that front.

The key word here is theoretical. This was only seen in test-tube research, never reported in real people, so I wouldn't lose sleep over it. The pseudoephedrine (decongestant) side isn't really affected by this. If you take both regularly, just mention it to your pharmacist so we can keep an eye on how you feel.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Takahashi T, Kaku T, Sato T, et al. Effects of Acanthopanax senticosus HARMS extract on drug transport in human intestinal cell line Caco-2. J Nat Med. 2010;64(1):55-62. PubMed
  2. Freye E, GLeske J. Siberian ginseng results in beneficial effects on glucose metabolism in diabetes type 2 patients: a double blind placebo-controlled study in comparison to panax ginseng. Int J Clin Nutr. 2013;1(1):11-17.
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Fexofenadine, Pseudoephedrine also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, eleuthero might increase levels of drugs metabolized by CYP3A4.
In vitro and animal research suggest that standardized extracts of eleuthero might inhibit CYP3A4. However, research in healthy human volunteers has found that taking eleuthero 485 mg twice daily for 14 days does not inhibit CYP3A4 drug metabolism.
Severity Minor Likelihood Unlikely Evidence B

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the short version on combining eleuthero with Allegra-D (fexofenadine and pseudoephedrine). The concern on file is that eleuthero might slow down a liver enzyme called CYP3A4, which could let certain drugs build up a bit. But honestly, this one is mostly theoretical. It comes from lab and animal studies, and when researchers actually gave eleuthero to healthy people for two weeks, it did not meaningfully block that enzyme.

Neither fexofenadine nor pseudoephedrine is a prodrug, so nothing here flips. If levels did nudge upward, the part to watch would be the pseudoephedrine side: things like a racing heart, jitteriness, trouble sleeping, or higher blood pressure. For most people this is low-risk, but if you have high blood pressure or heart issues, run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Harkey MR, Henderson GL, Zhou L, et al. Effects of Siberian ginseng (Eleutherococcus senticosus) on c-DNA-expressed P450 drug metabolizing enzymes. Alt Ther 2001;7:S14.
  2. Donovan JL, DeVane CL, Chavin KD, et al. Siberian Ginseng (Eleutheroccus senticosus) Effects on CYP2D6 and CYP3A4 Activity in Normal Volunteers. Drug Metab Dispos 2003;31:519-22.. PubMed
Minor

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP)

3 of 3

Fexofenadine, Pseudoephedrine also falls under ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP).

Theoretically, eleuthero might decrease levels of drugs metabolized by OATP.
In vitro research suggests that eleuthero inhibits OATP2B1, which might reduce the bioavailability of oral drugs that are substrates of OATP2B1. Due to the weak inhibitory effect identified in this study, this interaction is not likely to be clinically significant.
Severity Minor 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 the gist for your Allegra-D. The fexofenadine part relies on a little transporter called OATP to get absorbed from your gut into your bloodstream. In lab dish studies, eleuthero seems to mildly block that transporter, so in theory it could nudge your fexofenadine levels down a touch and make it work a little less well for your allergies (think sneezing or runny nose creeping back). The pseudoephedrine decongestant piece isn't really affected by this.

Honestly, this is very weak, theory-only evidence from test tubes, not real people, and the researchers themselves said it's unlikely to matter clinically. I wouldn't lose sleep over it. If you take eleuthero regularly and notice your allergy relief slipping, just mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fuchikami H, Satoh H, Tsujimoto M, Ohdo S, Ohtani H, Sawada Y. Effects of herbal extracts on the function of human organic anion-transporting polypeptide OATP-B. Drug Metab Dispos 2006;34:577-82. 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

Eleuthero Also Interacts With Other Medications

Eleuthero has 678 moderate, 461 minor known drug interactions in our database — the Fexofenadine, Pseudoephedrine one above is among them. If you take anything else, check it against the full list below.

Moderate 678 Minor 461 No known interaction 1,691 (incl. Fexofenadine, Pseudoephedrine)
Taking anything else?

Check Another of Your Medications Against Eleuthero

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

From our Q&A

Questions About Eleuthero or Fexofenadine, Pseudoephedrine

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

This page covers Eleuthero only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fexofenadine, Pseudoephedrine page lists 188 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Apple (major), Ephedra (major), Grapefruit (major) and Peyote (major).

By severity: 9 major · 140 moderate · 39 minor.

From our pharmacist’s overview on the Fexofenadine, Pseudoephedrine page

“The person reaching for Allegra D (fexofenadine with pseudoephedrine) is congested, itchy, and probably washing the tablet down with juice or coffee, which is exactly where the trouble starts. This combination deserves genuine care.”

Reviewed by 2 · Jul 18, 2026

Open the Fexofenadine, Pseudoephedrine interaction page

One more smart check

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

We hold 3,795 real supplement products containing Eleuthero, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Eleuthero. Your product may carry other ingredients that interact with Fexofenadine, Pseudoephedrine too, on top of Eleuthero — 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 Eleuthero and Fexofenadine, Pseudoephedrine 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 Eleuthero
Top 5%

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

29 days ago today
Medication Fexofenadine, Pseudoephedrine
Top 5%

#78 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 Eleuthero

What is Eleuthero?

Eleuthero
  • Fatigue and low energy
  • Physical and athletic performance
  • Stress resistance (adaptogen)
  • Immune support
  • Mental focus and alertness

Eleuthero is an herb traditionally used as an 'adaptogen' to fight fatigue, boost energy, and help the body handle stress. The scientific evidence behind these uses is limited and mixed, so it should not replace proven treatments. It is generally well tolerated short-term, but pregnant and breastfeeding people and those with certain conditions should avoid it or check with a healthcare provider first.

Read the full Eleuthero monograph & all interactions
Keep checking

Other Drugs & Eleuthero

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

0Major
678Moderate
461Minor
1,690No known interaction
678 Moderate 461 Minor 1,690 No interaction
Moderate

678 interactions

Showing 60 of 678 moderate interactions — see all 678 on the Eleuthero page.

Minor

461 interactions

Showing 60 of 461 minor interactions — see all 461 on the Eleuthero page.

No interaction 1,690 drugs checked — show the list

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

Showing the 60 most looked-up of 1,690 medications checked with no known interaction — see the full Eleuthero list.

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

Can you take Eleuthero with Fexofenadine, Pseudoephedrine?
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.
Why are there 3 interactions listed for Eleuthero and Fexofenadine, Pseudoephedrine?
Fexofenadine, Pseudoephedrine belongs to more than one drug category, and Eleuthero interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Eleuthero and Fexofenadine, Pseudoephedrine 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

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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.