Drug & supplement interaction

Shiitake Mushroom + Meperidine

Meperidine brand names: Pethadol, Cytospaz.

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

Shiitake Mushroom has a moderate interaction with Meperidine. Theoretically, shiitake mushroom might decrease levels of drugs metabolized by CYP2D6.

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

Shiitake Mushroom and Meperidine

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

Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

Why this applies to Meperidine

Meperidine falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Shiitake Mushroom interacts with.

Theoretically, shiitake mushroom might decrease levels of drugs metabolized by CYP2D6.
In vitro studies suggest that the shiitake mushroom extract AHCC might induce the CYP2D6 enzyme. This effect 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 for meperidine (Demerol) and shiitake. Lab studies hint that a concentrated shiitake extract called AHCC might speed up an enzyme called CYP2D6, which helps your body process meperidine. If that enzyme works faster, your body could clear the drug a bit quicker, which in theory might make your pain relief feel weaker or shorter-lasting.

Now, the honest part: this only comes from test-tube research, and it has never actually been seen in people. Eating shiitake as food is very unlikely to matter at all. Concentrated supplements are the bigger question mark. If you're relying on meperidine for real pain and want to add a shiitake supplement, just run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Mach, C. M., Fugii, H., Wakame, K., and Smith, J. Evaluation of active hexose correlated compound hepatic metabolism and potential for drug interactions with chemotherapy agents. J Soc Integr.Oncol. 2008;6(3):105-109.
  2. Smith, J. A., Hunter, R. J., Fujii, H., Wakame, K., and Wolf, J. Defining Synergistic Activity ofthe Combination of Active Hexose Correlated Compound (AHCC) with Liposomal Doxorubicin (Doxil). Presented at the 18th International Congress on Nutrition and

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

Shiitake Mushroom Also Interacts With Other Medications

Shiitake Mushroom has 311 moderate known drug interactions in our database — the Meperidine one above is one of them. If you take anything else, check it against the full list below.

Moderate 311 No known interaction 2,519 (incl. Meperidine)
Taking anything else?

Check Another of Your Medications Against Shiitake Mushroom

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

Everything else you take

See Every Supplement That Interacts With Meperidine

This page covers Shiitake Mushroom only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Meperidine page lists 155 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Kava (major).

By severity: 8 major · 124 moderate · 23 minor.

Open the Meperidine interaction page

One more smart check

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

We hold 1,613 real supplement products containing Shiitake Mushroom, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Shiitake Mushroom. Your product may carry other ingredients that interact with Meperidine too, on top of Shiitake Mushroom — 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 Shiitake Mushroom and Meperidine 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 Shiitake Mushroom
Top 25%

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

29 days ago today
Medication Meperidine
Steady interest

#2,624 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 Shiitake Mushroom

What is Shiitake Mushroom?

  • Immune support
  • General wellness and nutrition
  • Cholesterol and heart health
  • Adjunct in cancer care (lentinan, AHCC)
  • Antioxidant support

Shiitake is a popular edible mushroom that is nutritious and safe to eat as food for most people. Some of its extracts (like lentinan and AHCC) have been studied as immune support, mainly alongside cancer treatment, but evidence for most supplement uses is limited. Talk with your pharmacist or doctor before using concentrated shiitake supplements.

Read the full Shiitake Mushroom monograph & all interactions
Medication

About Meperidine

What Is Meperidine Used For?

Brand names: Pethadol, Cytospaz

Meperidine is prescribed for severe pain when other treatments haven't worked or aren't tolerated. It's also used before surgery to help patients relax and to support anesthesia, and it can be used during labor and delivery for pain relief.

Because it carries real risks — including addiction and serious breathing problems — meperidine is reserved for situations where milder options simply aren't enough.

See full Meperidine drug information
Keep checking

Other Drugs & Shiitake Mushroom

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

0Major
311Moderate
0Minor
2,518No known interaction
311 Moderate 2,518 No interaction
Moderate

311 interactions

Showing 60 of 311 moderate interactions — see all 311 on the Shiitake Mushroom page.

No interaction 2,518 drugs checked — show the list

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

Showing the 60 most looked-up of 2,518 medications checked with no known interaction — see the full Shiitake Mushroom list.

See the full Shiitake Mushroom interactions page
See every supplement checked against Meperidine, 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
Shiitake Mushroom monograph › Uses, safety, and every drug interaction in one place Meperidine supplement interactions › Every supplement checked against Meperidine, ranked by severity Meperidine 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 Shiitake Mushroom and Meperidine Together: Common Questions

Can you take Shiitake Mushroom with Meperidine?
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 Shiitake Mushroom and Meperidine 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 Meperidine and Shiitake Mushroom?

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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.