Drug & supplement interaction

Calea Zacatechichi + Clemastine

Clemastine brand name: Tavist Allergy.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Calea Zacatechichi and Clemastine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Calea Zacatechichi and Clemastine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Clemastine and Calea Zacatechichi in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Calea Zacatechichi safety at a glance

Calea Zacatechichi overall Use caution It has a long folk-use history but little modern safety data, and it can cause nausea and vomiting.
Pregnancy Avoid There is no reliable safety data, so it is best avoided during pregnancy.
Breastfeeding Avoid There is no reliable safety data, so it is best avoided while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Clemastine and Calea Zacatechichi? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Clemastine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Clemastine is filed under 4 classifications — including anticholinergic drugs, photosensitizing drugs, seizure threshold lowering drugs. Calea Zacatechichi has documented interactions with 2 drug classes — the most serious being antidiabetes drugs (minor) and cns depressants (minor) — and none of Clemastine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Calea Zacatechichi Does Interact With Other Medications

Calea Zacatechichi has 334 minor known drug interactions in our database — Clemastine isn’t one of them. If you take anything else, check it against the full list below.

Minor 334 No known interaction 2,496 (incl. Clemastine)
Taking anything else?

Check Another of Your Medications Against Calea Zacatechichi

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

What to actually watch for

No Interaction Found — But Data Suggests Calea Zacatechichi and Clemastine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Drowsiness Additional detail

    Calea Zacatechichi

    “There is currently a limited amount of information on the adverse effects of Calea zacatechichi. Observations in healthy volunteers indicate that it is bitter tasting and may cause vomiting and somnolence.”

    Calea Zacatechichi · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    “In healthy volunteers, a methanol extract of Calea zacatechichi produces somnolence with short periods of light sleep and decreases in deep slow-wave sleep and rapid eye movement (REM) sleep.”

    Calea Zacatechichi · Natural Medicines adverse-effect record, reported in insomnia.

    1 source cited
    1. 23602. Mayagoitia, L., Diaz, J. L., Contreras, C. M. Psychopharmacologic analysis of an alleged oneirogenic plant: Calea zacatechichi. J Ethnopharmacol. 1986;18:229-243. PubMed

    Clemastine

    Listed in the ADVERSE REACTIONS section of the FDA label for Clemastine. Read the label on DailyMed ›

  • Vomiting Additional detail

    Calea Zacatechichi

    “Observations in healthy volunteers indicate that Calea zacatechichi is bitter tasting and can cause nausea, vomiting, and retching.”

    Calea Zacatechichi · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 23602. Mayagoitia, L., Diaz, J. L., Contreras, C. M. Psychopharmacologic analysis of an alleged oneirogenic plant: Calea zacatechichi. J Ethnopharmacol. 1986;18:229-243. PubMed

    Clemastine

    Listed in the ADVERSE REACTIONS section of the FDA label for Clemastine. Read the label on DailyMed ›

  • Nausea Additional detail

    Calea Zacatechichi

    Recorded for Calea Zacatechichi in the same Natural Medicines adverse-effect record shown under Vomiting above.

    Clemastine

    Listed in the ADVERSE REACTIONS section of the FDA label for Clemastine. Read the label on DailyMed ›

Effects for Clemastine come from the ADVERSE REACTIONS section of its FDA label; effects for Calea Zacatechichi come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Clemastine Is Prescribed For, and What Calea Zacatechichi Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Clemastine is a prescription medicine with approved uses on its FDA label. Calea Zacatechichi is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Clemastine is prescribed for: 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.

Calea Zacatechichi has been studied for:

  • Urticaria studied, not established Calea Zacatechichi has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Calea Zacatechichi for urticaria

    Although there is interest in using topical Calea zacatechichi for urticaria, there is insufficient reliable information about the clinical effects of Calea zacatechichi for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Clemastine on your own; if you are taking Calea Zacatechichi for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Calea Zacatechichi 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 Calea Zacatechichi 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 Calea Zacatechichi 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

One more smart check

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

We hold 21 real supplement products containing Calea Zacatechichi, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Calea Zacatechichi. Even though Calea Zacatechichi itself has no known interaction with Clemastine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Calea Zacatechichi 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 Calea Zacatechichi
Steady interest

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

29 days ago today
Medication Clemastine
Steady interest

#2,429 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Calea Zacatechichi reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Calea Zacatechichi and Clemastine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Calea Zacatechichi

What is Calea Zacatechichi?

  • Promoting vivid or lucid dreams
  • Sleep and relaxation
  • Digestive upset
  • Fever
  • Traditional ritual use

Calea zacatechichi, often called 'dream herb,' is a Mexican plant traditionally used to encourage vivid dreams and to treat digestive complaints and fever. Human research is very limited, so its benefits are not well proven, and its safety has not been carefully studied. It tastes very bitter, can cause nausea, and should be avoided during pregnancy and breastfeeding.

Calea ternifolia · Asteraceae · Leaves and flowering tops (dried) · Dried leaf tea, capsules, tincture/liquid extract, and smoked dried leaf

An interaction check asks whether these two react with each other — it does not ask whether Calea Zacatechichi is a good idea for someone in your situation. Here is what our Calea Zacatechichi record says about it on its own.

Calea Zacatechichi: dosing

There is no established or standardized dose for Calea zacatechichi. The amount of active compounds can vary a lot from product to product, which makes safe dosing hard to judge.If you choose to use it, follow the directions on the product label and do not exceed them.

From our Calea Zacatechichi monograph — the full record covers uses, side effects and every documented interaction.

Read the full Calea Zacatechichi 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 & Calea Zacatechichi

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

0Major
0Moderate
334Minor
2,495No known interaction
334 Minor 2,495 No interaction
Minor

334 interactions

Showing 60 of 334 minor interactions — see all 334 on the Calea Zacatechichi page.

No interaction 2,495 drugs checked — show the list

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

Showing the 60 most looked-up of 2,495 medications checked with no known interaction — see the full Calea Zacatechichi list.

See the full Calea Zacatechichi interactions page
See every supplement checked against Clemastine, ranked by severity
Evidence & sources

Calea Zacatechichi References

The 2 references that drive our Calea Zacatechichi monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Mayagoitia, L., Diaz, J. L., Contreras, C. M. Psychopharmacologic analysis of an alleged oneirogenic plant: Calea zacatechichi. J Ethnopharmacol. 1986;18:229-243. PubMed
  2. Roman, Ramos R., Alarcon-Aguilar, F., Lara-Lemus, A., and Flores-Saenz, J. L. Hypoglycemic effect of plants used in Mexico as antidiabetics. Arch.Med.Res 1992;23:59-64.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Calea Zacatechichi and Clemastine Together: Common Questions

Is it safe to take Calea Zacatechichi with Clemastine?
We do not list a known interaction between Calea Zacatechichi and Clemastine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Calea Zacatechichi and Clemastine have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Calea Zacatechichi and Clemastine used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Calea Zacatechichi in each. That is a conversation for your prescriber, especially if Clemastine is being adjusted to a target.
How was the Calea Zacatechichi and Clemastine combination checked?
Interactions in our licensed database are recorded against drug classes. Clemastine is filed under 4 classifications, and Calea Zacatechichi has documented interactions with 2 drug classes — none of Clemastine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Calea Zacatechichi interact with any other medications?
Yes. Calea Zacatechichi has 334 documented drug interactions in our database — Clemastine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Clemastine interact with any supplements?
Yes. Clemastine has documented interactions with 72 supplements in our database — Calea Zacatechichi is not one of them. The Clemastine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Calea Zacatechichi monograph Uses, safety profile, and every drug interaction in one place Clemastine drug information The full plain-English guide to this medication Clemastine supplement interactions Every supplement checked against Clemastine, 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 References The 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Clemastine and Calea Zacatechichi?

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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.