Drug & supplement interaction

Jimson Weed + Meperidine, Promethazine

Meperidine, Promethazine brand names: Meprozine, Mepergan.

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

Jimson Weed has a moderate interaction with Meperidine, Promethazine. Theoretically, jimson weed may increase anticholinergic effects and adverse effects.

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

Jimson Weed and Meperidine, Promethazine

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

Moderate

ANTICHOLINERGIC DRUGS

Why this applies to Meperidine, Promethazine

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

Theoretically, jimson weed may increase anticholinergic effects and adverse effects.
Jimson weed contains alkaloids with anticholinergic effects, such as atropine and scopolamine. Use with other anticholinergic drugs may cause additive effects.
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

First things first: Jimson Weed is genuinely dangerous and isn't something I'd ever recommend taking, on its own or with anything else. But here's the specific concern with your Meprozine or Mepergan, which combines meperidine (a pain reliever) with promethazine (an antihistamine). Promethazine already has strong anticholinergic activity, meaning it blocks the same nervous system messenger that Jimson Weed's compounds (atropine and scopolamine) block.

So putting them together stacks those effects. You could see worse dry mouth, blurry vision, constipation, trouble urinating, fast heartbeat, confusion, and severe drowsiness or sedation. This is based on how these chemicals work rather than hard studies, but the overlap is real. Please don't combine them, and talk with your pharmacist or doctor about any concerns.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. Burnham TH, ed. Drug Facts and Comparisons, Updated Monthly. Facts and Comparisons, St. Louis, MO.
  3. Sasaki, T., Yamazaki, K., Yamori, T., and Endo, T. Inhibition of proliferation and induction of differentiation of glioma cells with Datura stramonium agglutinin. Br.J Cancer 10-7-2002;87(8):918-923. PubMed
  4. Al Shaikh, A. M. and Sablay, Z. M. Hallucinogenic plant poisoning in children. Saudi.Med.J 2005;26(1):118-121. DOI
  5. Pavlov, A., Berkov, S., Weber, J., and Bley, T. Hyoscyamine Biosynthesis in Datura stramonium Hairy Root In Vitro Systems with Different Ploidy Levels. Appl Biochem Biotechnol 5-29-2008; PubMed
  6. Nogue, S., Pujol, L., Sanz, P., and de la, Torre R. Datura stramonium poisoning. Identification of tropane alkaloids in urine by gas chromatography-mass spectrometry. J Int Med.Res. 1995;23(2):132-137.
  7. Roblot, F., Montaz, L., Delcoustal, M., Gaboriau, E., Chavagnat, J. J., Morichaud, G., Pourrat, O., Scepi, M., and Patte, D. [Datura stramonium poisoning: the diagnosis is clinical, treatment is symptomatic]. Rev.Med.Interne 1995;16(3):187-190.

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

Jimson Weed Also Interacts With Other Medications

Jimson Weed has 194 moderate 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.

Moderate 194 No known interaction 2,636 (incl. Meperidine, Promethazine)
Taking anything else?

Check Another of Your Medications Against Jimson Weed

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

Everything else you take

See Every Supplement That Interacts With Meperidine, Promethazine

This page covers Jimson Weed 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

One more smart check

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

We hold 1 real supplement products containing Jimson Weed, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Jimson Weed. Your product may carry other ingredients that interact with Meperidine, Promethazine too, on top of Jimson Weed — 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 Jimson Weed 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 Jimson Weed
Steady interest

#1,070 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Meperidine, Promethazine
Top 25%

#365 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 Jimson Weed

What is Jimson Weed?

  • Asthma and breathing problems (historical/folk use)
  • Pain relief
  • Recreational hallucinogen (highly dangerous misuse)
  • Muscle spasms
  • Skin conditions (traditional topical use)

Jimson Weed is a highly poisonous plant that contains powerful nerve-affecting compounds, and even small amounts can cause severe poisoning, hallucinations, or death. It is not a safe supplement, and there is no reliable evidence supporting its use for any health condition. Do not use Jimson Weed in any form.

Read the full Jimson Weed monograph & all interactions
Keep checking

Other Drugs & Jimson Weed

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

0Major
194Moderate
0Minor
2,635No known interaction
194 Moderate 2,635 No interaction
Moderate

194 interactions

Showing 60 of 194 moderate interactions — see all 194 on the Jimson Weed page.

No interaction 2,635 drugs checked — show the list

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

Showing the 60 most looked-up of 2,635 medications checked with no known interaction — see the full Jimson Weed list.

See the full Jimson Weed 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
Jimson Weed 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 Jimson Weed and Meperidine, Promethazine Together: Common Questions

Can you take Jimson Weed with Meperidine, Promethazine?
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 Jimson Weed and Meperidine, Promethazine 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, Promethazine and Jimson Weed?

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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.