Drug & supplement interaction

Datura Wrightii + Clemastine

Clemastine brand name: Tavist Allergy.

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

Datura Wrightii has a moderate interaction with Clemastine. Datura wrightii contains atropine and scopolamine, as well as other tropane alkaloids with anticholinergic activity.

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

Datura Wrightii and Clemastine

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

Moderate

ANTICHOLINERGIC DRUGS

Why this applies to Clemastine

Clemastine falls under ANTICHOLINERGIC DRUGS — the group Datura Wrightii interacts with.

Datura wrightii contains atropine and scopolamine, as well as other tropane alkaloids with anticholinergic activity. Concomitant use of Datura wrightii with anticholinergic drugs might increase anticholinergic effects and adverse effects. Some anticholinergic drugs include amantadine, atropine, belladonna alkaloids, phenothiazines, scopolamine, and tricyclic antidepressants.
Severity Moderate 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 know about pairing these two: clemastine is an older antihistamine that already has its own anticholinergic (drying) effects. Datura wrightii is loaded with atropine and scopolamine, which block the very same acetylcholine system. So stacking them doesn't cancel out, it piles on. You could see exaggerated dry mouth, blurry vision, constipation, trouble urinating, a racing heart, drowsiness, and in worse cases confusion or hallucinations.

This concern is based on how the two work rather than on hard studies, so it's more of a predictable pharmacology warning than a proven event. Honestly though, my bigger worry is that Datura wrightii itself is genuinely poisonous and isn't something I'd ever recommend taking. Please talk with your pharmacist or doctor before combining anything like this.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Adams, JD Jr, Garcia C. Spirit, Mind and Body in Chumash Healing. Evid Based Complement Alternat Med 2005;2(4):459-463. PubMed
  2. Evans WC, Woolley JG. The alkaloids of Datura meteloides D.C. J Chem Soc Perkin 1. 1965;4936-4939.

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

Datura Wrightii Also Interacts With Other Medications

Datura Wrightii has 225 moderate known drug interactions in our database — the Clemastine one above is one of them. If you take anything else, check it against the full list below.

Moderate 225 No known interaction 2,605 (incl. Clemastine)
Taking anything else?

Check Another of Your Medications Against Datura Wrightii

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

From our Q&A

Questions About Datura Wrightii or Clemastine

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

This page covers Datura Wrightii only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Clemastine page lists 72 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Henbane (major), Scopolia (major), Alfalfa (moderate) and Angel's Trumpet (moderate).

By severity: 3 major · 57 moderate · 12 minor.

From our pharmacist’s overview on the Clemastine page

“Clemastine (Tavist Allergy) is an older, sedating antihistamine that already dries the mouth, blurs vision, and slows the gut, and that is exactly why this list earns real caution rather than a quick skim. Thirty of the 72 supplements on file pile the same drying, sedating anticholinergic load on top, and two of the three major-rated e…”

Reviewed by 2 · Jul 18, 2026

Open the Clemastine interaction page

How much people look this up

Where Datura Wrightii and Clemastine 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 Datura Wrightii
Steady interest

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

29 days ago today
Medication Clemastine
Top half

#1,387 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 Datura Wrightii

What is Datura Wrightii?

  • Traditional ritual and ceremonial use
  • Pain relief (traditional/topical)
  • Asthma and breathing complaints (historical)
  • Hallucinogenic/psychoactive effects
  • Skin and wound applications (folk use)

Datura wrightii (sacred datura or jimsonweed relative) is a highly poisonous desert plant that has been used in some traditional and ceremonial settings. It is not a safe dietary supplement — even small amounts can cause severe poisoning, hallucinations, and death. We strongly advise against using it.

Read the full Datura Wrightii monograph & all interactions
Medication

About Clemastine

What Is Clemastine Used For?

Brand name: Tavist Allergy

Clemastine treats symptoms of allergic rhinitis (hay fever and similar nasal allergies) — including sneezing, runny nose, itching, and watery eyes. The oral solution (Clemastine Fumarate syrup) is indicated for adults and children aged 6 through 12 years. The tablets (Clemastine Fumarate and Clemsza) are indicated for adults.

Clemastine also treats mild, uncomplicated allergic skin reactions — specifically urticaria (hives) and angioedema (swelling under the skin) — at the appropriate dosage level, in both the oral solution and tablet forms.

See full Clemastine drug information
Keep checking

Other Drugs & Datura Wrightii

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

0Major
225Moderate
0Minor
2,604No known interaction
225 Moderate 2,604 No interaction
Moderate

225 interactions

Showing 60 of 225 moderate interactions — see all 225 on the Datura Wrightii page.

No interaction 2,604 drugs checked — show the list

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

Showing the 60 most looked-up of 2,604 medications checked with no known interaction — see the full Datura Wrightii list.

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

Can you take Datura Wrightii with Clemastine?
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 Datura Wrightii and Clemastine 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 Clemastine and Datura Wrightii?

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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.