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California Poppy

California poppy is a golden-flowered plant whose extracts contain alkaloids that appear to act on calming pathways in the brain, including GABA and serotonin receptors. People mostly look at it for anxiety, but the evidence is limited: a trial of about 264 people found a combination product with hawthorn and magnesium eased mild to moderate anxiety. Because that product was a blend, and the other findings come mostly from rodents and lab work, it's unclear what California poppy does on its own.

Sources: PMID 14696882; PMID 14741074

Best evidence
Grade C
Conditions studied
1
Outcomes
4
Graded outcomes
0013

Evidence by condition

  • Strong
  • Moderate
  • Limited
  • Very limited

1 condition, plus general outcomes

Anxiety Disorders (Other)

Anxiety Disorders (Other): outcomes studied for California Poppy
GradeOutcomeEffectSizeStudiesPeopleStudies list
Anxiety

In rodent models, California poppy extracts showed anxiolytic effects in elevated plus-maze and behavioral tests, attributed to GABA-A receptor and 5-HT1A receptor modulation by isoquinoline alkaloids. One double-blind, placebo-controlled RCT (n=264) found a combination product (Sympathyl) containing California poppy, hawthorn, and magnesium significantly reduced mild-to-moderate anxiety scores, though the individual contribution of California poppy cannot be isolated from the other ingredients.

Improves (the measure goes down)Moderate effect10 studies264 people

Studies that measured anxiety

General

General: outcomes studied for California Poppy
GradeOutcomeEffectSizeStudiesPeopleStudies list
Sleep Quality

In rodent studies, California poppy extracts prolonged barbiturate-induced sleeping time and reduced locomotor activity, consistent with sedative properties mediated through GABA-A receptor and benzodiazepine binding site modulation. No human clinical trials have evaluated California poppy as a standalone sleep aid.

Improves (the measure goes up)Moderate effect7 studies

Studies that measured sleep quality

Pain

California poppy alkaloids (protopine, escholtzine) demonstrate weak binding affinity for opioid receptors in vitro, and the plant has longstanding traditional use for pain relief among Native American populations. Limited animal data suggest mild analgesic effects, but no human clinical trials have evaluated standalone analgesic efficacy.

Improves (the measure goes down)Small effect6 studies

Studies that measured pain

Drug Metabolism Interactions

In vitro studies demonstrate that California poppy alkaloids modulate cytochrome P450 enzymes (CYPs), P-glycoprotein (P-gp), and pregnane X receptor (PXR), suggesting potential for herb-drug interactions. A 2023 study confirmed alkaloid intestinal permeability and microbiota interactions, but clinical significance in humans remains uncharacterized.

Improves (the measure goes up)Small effect6 studies

Studies that measured drug metabolism interactions

Key findings

  • AnxietyAnxiety Disorders (Other)Improves (the measure goes down)
  • Sleep QualityImproves (the measure goes up)
  • PainImproves (the measure goes down)

Shop California Poppy

Third-party tested California Poppy products. The evidence above is limited, so read it before you buy.

  • Grade C

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Studies cited

12 studies from PubMed

  1. Comprehensive Metabolomic Profiling and Biological Activity Analysis of Eschscholzia californica Extracts Using LC-ESI-QTOF-MS.Food Science & Nutrition, 2025 · PMID 40909255
  2. Alkaloids in commercial preparations of California poppy - Quantification, intestinal permeability and microbiota interactions.Biomedicine & Pharmacotherapy, 2023 · PMID 37673017
  3. Modulation of CYPs, P-gp, and PXR by Eschscholzia californica (California Poppy) and Its Alkaloids.Planta Medica, 2016 · PMID 27054913
  4. Modulatory Effects of Eschscholzia californica Alkaloids on Recombinant GABAA Receptors.Biochemistry Research International, 2015 · PMID 26509084
  5. Plant-based medicines for anxiety disorders, Part 1: a review of preclinical studies.CNS Drugs, 2013 · PMID 23436255
  6. Alkaloids from Eschscholzia californica and their capacity to inhibit binding of [3H]8-Hydroxy-2-(di-N-propylamino)tetralin to 5-HT1A receptors in Vitro.Journal of Natural Products, 2006 · PMID 16562853
  7. A double-blind, placebo-controlled study of an herbal combination product for the treatment of mild to moderate anxietyCurr Med Res Opin, 2004 · PMID 14696882
  8. Double-blind, randomised, placebo-controlled study to evaluate the efficacy and safety of a fixed combination containing two plant extracts (Crataegus oxyacantha and Eschscholtzia californica) and magnesium in mild-to-moderate anxiety disorders.Current Medical Research and Opinion, 2004 · PMID 14741074
  9. Neurotropic action of the hydroethanolic extract of Eschscholzia californicaPlanta Med, 2001 · PMID 15070161
  10. Neurophysiological effects of an extract of Eschscholzia californica Cham. (Papaveraceae).Phytotherapy Research, 2001 · PMID 11507727
  11. Binding of various isoquinoline alkaloids to biogenic amine receptorsPlanta Med, 1997 · PMID 8991978
  12. Behavioural effects of Eschscholzia californica: sedative and anxiolytic propertiesPlanta Med, 1991 · PMID 1353889