Herb & supplement monograph

Calea Zacatechichi Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Calea Zacatechichi interacts with medications. The heart of this page is the interaction list — every drug Calea Zacatechichi is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Calea Zacatechichi is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Calea Zacatechichi Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Calea Zacatechichi drug interaction appears low for most people. Every interaction on record for this herb is rated minor, with none classified as moderate or major.

Interactions deserving the most attention

Two areas are worth a closer look, though both rest on limited evidence. Animal research shows Calea zacatechichi can lower blood glucose, so combining it with diabetes medications could in theory add to their effect and nudge blood sugar lower than expected. The herb has also caused drowsiness in animals and humans, so pairing it with sedatives and other CNS depressants might increase sleepiness. Neither effect has been confirmed as clinically meaningful in human studies.

What the rest of the list means

Although the list of interacting medications is long, that number reflects how many individual drugs fall into these two broad groups, not hundreds of separate proven problems. The concerns are theoretical, drawn mostly from animal and lab research rather than documented harm in people. For most medications, no meaningful interaction with this herb has been shown.

Check your medications against Calea Zacatechichi

Based on HelloPharmacist’s Calea Zacatechichi interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Calea Zacatechichi

334 medications have a known interaction with Calea Zacatechichi, graded by severity. Select any drug for the full evidence-based detail.

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Tell us the medications you take and we’ll check each one against Calea Zacatechichi using our pharmacist-reviewed interaction data.

AI summaries are generated from our Calea Zacatechichi interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Calea Zacatechichi combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Calea Zacatechichi affects

Every type of medication (drug category) Calea Zacatechichi is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Calea Zacatechichi interacts with

Antidiabetes DrugsCns Depressants

Antidiabetes Drugs

Theoretically, taking Calea zacatechichi with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research shows that Calea zacatechichi lowers blood glucose levels. Theoretically, combining Calea zacatechichi with antidiabetes drugs might result in additive effects.

Likelihood Possible Evidence D

Cns Depressants

Theoretically, Calea zacatechichi might increase the sedative effects of CNS depressants.
Calea zacatechichi can cause CNS depression in animals and humans.

Likelihood Possible Evidence D

Monograph

Calea Zacatechichi: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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.

Scientific name: Calea ternifolia
Family: Asteraceae
Part used: Leaves and flowering tops (dried)
Common forms: Dried leaf tea, capsules, tincture/liquid extract, and smoked dried leaf

People commonly use it for

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

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

It has a long folk-use history but little modern safety data, and it can cause nausea and vomiting.

PregnancyInsufficient reliable information

Insufficient reliable evidence; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable evidence; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Calea zacatechichi (botanical name Calea ternifolia) is a shrubby plant in the daisy family that grows in Mexico and parts of Central America. It is sometimes called the "dream herb" or "bitter grass" because of its very bitter taste and its traditional reputation for affecting dreams.

It has a long history of use among Indigenous peoples of Mexico, who have used the dried leaves and flowers as a tea, in smoke, or as an extract. Traditionally it was taken to encourage vivid or meaningful dreams during sleep and to help with stomach problems and fever.

Today it is sold as a dietary supplement in the form of dried leaf, tea, capsules, and tinctures, often marketed for dreaming and relaxation.

How it works

The plant contains a mix of natural compounds, including bitter substances called sesquiterpene lactones, along with flavonoids and other plant chemicals. These bitter compounds are thought to be behind its strong taste and possibly some of its traditional effects on digestion.

How it might affect dreams or the brain is not well understood. Most ideas about its mechanism are based on laboratory studies or animal experiments, not on careful human research. Because of this, any explanation of "how it works" should be considered preliminary.

Effectiveness

Does Calea Zacatechichi work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 12 uses evaluated

12 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Calea Zacatechichi, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 12 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Anxiety