Plain packaging and health warnings made cannabis products less appealing in a large experiment

In a factorial experiment with 45,378 people in Canada and the US, plain packaging reduced cannabis product appeal while health warnings increased perceived harm and improved message recall, especially Canadian-style specific warnings.

Goodman, Samantha et al.·Preventive medicine·2021·Strong EvidenceRandomized Controlled Trial
RTHC-03164Randomized Controlled TrialStrong Evidence2021RETHINKTHC RESEARCH DATABASErethinkthc.com/research

Quick Facts

Study Type
Randomized Controlled Trial
Evidence
Strong Evidence
Sample
N=45,378

What This Study Found

Full branding was rated most appealing and plain packaging least (p<0.001). Health warnings made products significantly less appealing and more harmful than no warning (p<0.001). Canadian warnings (specific: pregnancy, adolescent risk, impaired driving) had higher recall than the US warning (general risk categories). White backgrounds with no branding were unexpectedly rated as less harmful than colored backgrounds.

Key Numbers

45,378 participants; 3x4 factorial design; plain packaging least appealing (p<0.001); health warnings reduced appeal and increased perceived harm (p<0.001); Canadian warnings had higher recall than US; white backgrounds rated less harmful (p<0.01)

How They Did This

Online factorial experiment randomizing participants to view cannabis packages across 3 health warning conditions (none, Canadian, US) and 4 branding conditions (plain to full branding). Measured product appeal, perceived harm, and free recall of warning messages.

Why This Research Matters

As more jurisdictions legalize cannabis, packaging regulations can meaningfully influence consumer perceptions. This large-scale evidence from a randomized design provides actionable guidance for regulators.

The Bigger Picture

The lessons from tobacco plain packaging appear to transfer to cannabis. Regulations that restrict branding and require prominent, specific health warnings could reduce product appeal and increase risk awareness among consumers.

What This Study Doesn't Tell Us

Online experiment may not perfectly simulate real-world purchasing decisions. Self-reported appeal and perceived harm may not predict actual behavior. Only tested visual package design, not actual products. Short-term perceptions measured.

Questions This Raises

  • ?Would plain packaging regulations actually reduce cannabis consumption, or just shift purchasing to unregulated markets?
  • ?Do the effects persist after repeated exposure to warnings?

Trust & Context

Key Stat:
Canadian-style specific warnings had higher recall than US general warnings
Evidence Grade:
Large randomized factorial experiment with clear effects, providing strong evidence for packaging regulation impact on perceptions.
Study Age:
Published in 2021 using 2019 data.
Original Title:
Influence of package colour, branding and health warnings on appeal and perceived harm of cannabis products among respondents in Canada and the US.
Published In:
Preventive medicine, 153, 106788 (2021)
Database ID:
RTHC-03164

Evidence Hierarchy

Meta-Analysis / Systematic Review
Randomized Controlled TrialGold standard for testing treatments
This study
Cohort / Case-Control
Cross-Sectional / Observational
Case Report / Animal Study

Participants are randomly assigned to treatment or placebo groups to test cause and effect.

What do these levels mean? →

Frequently Asked Questions

Do health warnings on cannabis work?

Yes. Products with warnings were rated significantly less appealing and more harmful. Specific warnings (like those used in Canada, mentioning pregnancy, youth, and driving risks) were better remembered than general risk statements used in the US.

Does plain packaging reduce appeal?

Yes. Moving from fully branded to plain packages significantly reduced product appeal. This is consistent with decades of evidence from tobacco plain packaging research.

Read More on RethinkTHC

Cite This Study

RTHC-03164·https://rethinkthc.com/research/RTHC-03164

APA

Goodman, Samantha; Rynard, Vicki L; Iraniparast, Maryam; Hammond, David. (2021). Influence of package colour, branding and health warnings on appeal and perceived harm of cannabis products among respondents in Canada and the US.. Preventive medicine, 153, 106788. https://doi.org/10.1016/j.ypmed.2021.106788

MLA

Goodman, Samantha, et al. "Influence of package colour, branding and health warnings on appeal and perceived harm of cannabis products among respondents in Canada and the US.." Preventive medicine, 2021. https://doi.org/10.1016/j.ypmed.2021.106788

RethinkTHC

RethinkTHC Research Database. "Influence of package colour, branding and health warnings on..." RTHC-03164. Retrieved from https://rethinkthc.com/research/goodman-2021-influence-of-package-colour

Access the Original Study

Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.

This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.