Drug & supplement interaction

Scopolia + Meperidine, Promethazine

Meperidine, Promethazine brand names: Meprozine, Mepergan.

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

Scopolia has a major interaction with Meperidine, Promethazine. The alkaloid constituents of scopolia, including hyoscyamine, scopolamine, and atropine, could potentiate the effects and adverse effects of anticholinergic drugs.

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

Scopolia and Meperidine, Promethazine

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

Major

ANTICHOLINERGIC DRUGS

Why this applies to Meperidine, Promethazine

Meperidine, Promethazine falls under ANTICHOLINERGIC DRUGS — the group Scopolia interacts with.

The alkaloid constituents of scopolia, including hyoscyamine, scopolamine, and atropine, could potentiate the effects and adverse effects of anticholinergic drugs.
Severity Major Likelihood Probable Evidence D

Interaction 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..

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

Here's the thing to understand about this combo. Your medicine pairs meperidine (a pain reliever) with promethazine, and promethazine already has its own anticholinergic (acetylcholine-blocking) activity. Scopolia is loaded with strong anticholinergic alkaloids like atropine, hyoscyamine, and scopolamine. Stack those on top of each other and you're essentially pushing the same effect twice.

What that can look like in real life: a very dry mouth, blurry vision, constipation, trouble emptying your bladder, a fast heartbeat, confusion, or feeling overheated. Older adults are especially sensitive. This warning is theoretical, based on how these compounds work rather than reported cases, but the alkaloids in scopolia are genuinely potent, so I wouldn't take the risk. Please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

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

Scopolia Also Interacts With Other Medications

Scopolia has 199 major, known drug interactions in our database — the Meperidine, Promethazine one above is one of them. If you take anything else, check it against the full list below.

Major 199 No known interaction 2,631 (incl. Meperidine, Promethazine)
Taking anything else?

Check Another of Your Medications Against Scopolia

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

Everything else you take

See Every Supplement That Interacts With Meperidine, Promethazine

This page covers Scopolia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Meperidine, Promethazine page lists 207 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 Henbane (major).

By severity: 10 major · 160 moderate · 37 minor.

From our pharmacist’s overview on the Meperidine, Promethazine page

“Meprozine combines meperidine, an opioid painkiller, with promethazine, a sedating antihistamine, so it already slows the brain on two fronts. I would read this list of 207 supplements and herbal ingredients with genuine care, starting with the 10 rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Meperidine, Promethazine interaction page

How much people look this up

Where Scopolia and Meperidine, Promethazine 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 Scopolia
Steady interest

#1,063 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Meperidine, Promethazine
Top 25%

#356 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 Scopolia

What is Scopolia?

Scopolia
  • Stomach and intestinal cramps
  • Motion sickness
  • Spasms and colic
  • Excess saliva or secretions
  • Pain relief (traditional)

Scopolia is a poisonous plant in the nightshade family that contains powerful anticholinergic alkaloids like atropine, hyoscyamine, and scopolamine. While these compounds are used in carefully measured prescription medicines, the raw plant is dangerous for self-treatment and should never be used without a doctor's supervision.

Read the full Scopolia monograph & all interactions
Keep checking

Other Drugs & Scopolia

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

199Major
0Moderate
0Minor
2,630No known interaction
199 Major 2,630 No interaction
Major

199 interactions

Showing 60 of 199 major interactions — see all 199 on the Scopolia page.

No interaction 2,630 drugs checked — show the list

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

Showing the 60 most looked-up of 2,630 medications checked with no known interaction — see the full Scopolia list.

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

Can you take Scopolia with Meperidine, Promethazine?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Scopolia and Meperidine, Promethazine interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Meperidine, Promethazine and Scopolia?

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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.