Drug & supplement interaction

Calea Zacatechichi + Cetirizine

Cetirizine brand names: Cetirizine, Zyrtec, Quzyttir.

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

Calea Zacatechichi has a minor interaction with Cetirizine. Theoretically, Calea zacatechichi might increase the sedative effects of CNS depressants.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Calea Zacatechichi and Cetirizine

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

Minor

CNS DEPRESSANTS

Why this applies to Cetirizine

Cetirizine falls under CNS DEPRESSANTS — the group Calea Zacatechichi interacts with.

Theoretically, Calea zacatechichi might increase the sedative effects of CNS depressants.
Calea zacatechichi can cause CNS depression in animals and humans.
Severity Minor 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 simple version: cetirizine (Zyrtec) is a newer antihistamine that's much less sedating than older ones, but it can still make some people feel drowsy or a little foggy. Calea zacatechichi, the 'dream herb,' has shown some calming or sedating activity in animals and in a few people. So putting the two together could, in theory, add up to more sleepiness than either one alone.

I want to be honest about the strength of this concern. It's theoretical, based on how these things work, not on solid studies in people taking them together. For most folks the effect would be mild at most. Still, if you notice extra drowsiness, go easy on driving and talk with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  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

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

Calea Zacatechichi Also Interacts With Other Medications

Calea Zacatechichi has 333 minor known drug interactions in our database — the Cetirizine one above is one of them. If you take anything else, check it against the full list below.

Minor 333 No known interaction 2,497 (incl. Cetirizine)
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.

From our Q&A

Questions About Calea Zacatechichi or Cetirizine

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 Cetirizine, 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 Cetirizine

This page covers Calea Zacatechichi only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Cetirizine page lists 100 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: 7 major · 78 moderate · 15 minor.

From our pharmacist’s overview on the Cetirizine page

“Cetirizine (Zyrtec) treats allergies, but even this newer antihistamine can make some people drowsy, and that weak spot is where most of its 100 documented supplement interactions land. Seventy-eight of the ingredients on this page add their own sedative pull on top of the drug's, and 7 of the 100 rate major, so treat this list with re…”

Reviewed by 2 · Jul 18, 2026

Open the Cetirizine 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. Your product may carry other ingredients that interact with Cetirizine too, on top of Calea Zacatechichi — 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 Calea Zacatechichi and Cetirizine 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

#1,264 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Cetirizine
Top 25%

#408 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 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.

Read the full Calea Zacatechichi monograph & all interactions
Medication

About Cetirizine Injection

What Is Cetirizine Injection Used For?

Brand names: Cetirizine, Zyrtec, Quzyttir

Quzyttir (cetirizine injection) is approved to treat acute urticaria — a sudden outbreak of hives — in adults and in children 6 months of age and older. It is given by intravenous (IV) injection in a medically supervised setting.

Quzyttir is not recommended for children under 6 years of age who have impaired kidney or liver function.

See full Cetirizine Injection 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
333Minor
2,496No known interaction
333 Minor 2,496 No interaction
Minor

333 interactions

Showing 60 of 333 minor interactions — see all 333 on the Calea Zacatechichi page.

No interaction 2,496 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 2,496 medications checked with no known interaction — see the full Calea Zacatechichi list.

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

Can you take Calea Zacatechichi with Cetirizine?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Calea Zacatechichi and Cetirizine interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Cetirizine and Calea Zacatechichi?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.