Abstract
Objectives. To characterize regulatory practices related to nonmedical cannabis warning labels in states across the United States that have legalized retail nonmedical cannabis.
Methods. In March 2024, we conducted a content analysis of regulations for nonmedical cannabis warning labels required on product packages in 20 states where, as of March 2024, adults could legally purchase nonmedical cannabis in retail environments. For each state, we examined requirements related to warning label content and characteristics.
Results. Required warning label content and characteristics varied widely across states. Only 2 states required a warning about mental health risks (10%) and 2 states required a warning for high potency products on risk of psychosis (10%). No states required front-of-package warning placement, only 2 states required rotating warnings (10%), and 4 states required contrasting colors (20%). Warnings were often verbose (mean = 57 words), vague, and had small or no minimum font size.
Conclusions. Opportunities exist for states to improve the alignment of their nonmedical cannabis warning label regulations with evidence that has been generated so far in cannabis effects, cannabis warning efficacy, and warning label design. (Am J Public Health. 2024;114(S8):S681–S684. https://doi.org/10.2105/AJPH.2024.307722)
As of March 2024, 24 US states (plus the District of Columbia) have legalized nonmedical (recreational) cannabis use. As legalization has spread, the prevalence of cannabis use has increased, and perceptions of cannabis risks have decreased.1 Although cannabis causes less harm than tobacco or alcohol,2 it is not without risks, which include harms to a fetus, car crashes, and worsened mental health (including psychosis, particularly for the developing brain).3
Researchers have emphasized the importance of ensuring access to knowledge of the potential harms of cannabis to promote informed and responsible use.1,4 Real-world evidence from Canada shows that well-designed cannabis warning labels (i.e., prominent, concise messages on evidence-based health risks that rotate periodically and use contrasting colors) can increase notice and recall of warning content, suggesting they are a promising strategy to inform consumers about cannabis risks.4-6
All 20 US states that have legalized retail nonmedical cannabis mandate warning labels on product packages. However, the influence of warning labels largely depends on their design.6 To our knowledge, the most recent content analysis of US cannabis warning label regulations was conducted in August 2019.7 Since then, the number of states that have legalized nonmedical cannabis has more than doubled, the cannabis market has evolved, and science has progressed. We, therefore, conducted an updated content analysis of US state nonmedical cannabis regulations in March 2024, exploring alignment with contemporary evidence and best practices to facilitate the development of evidence-based regulatory policy.
METHODS
Our study included 20 US states in which adults could legally purchase nonmedical cannabis containing greater than 0.3% THC in retail environments as of March 2024: Alaska, Arizona, California, Colorado, Connecticut, Illinois, Maine, Maryland, Massachusetts, Michigan, Missouri, Montana, Nevada, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, and Washington. We extracted regulatory text related to the content (e.g., health risks mentioned) and characteristics (e.g., font size, format, position, length) of nonmedical cannabis warning labels required on physical product packages. We found regulations on states’ cannabis regulatory agency websites and contacted agencies to verify that we had the most up-to-date text. We then conducted a content analysis using a mix of deductive and inductive codes to explore the prevalence of different warning features (Table 1). We used a Microsoft Excel (Microsoft, Redmond, WA) spreadsheet to track features across states’ warnings and generate descriptive statistics. Two research team members independently extracted and coded warning features, discussing any discrepancies to standardize our coding of warning labels and warning features.
TABLE 1—
Required Warning Features of US States That Have Legalized Retail Nonmedical Cannabis: March 2024
| Warning Features | No. (%) or Mean (Range) | Selected Example |
| Warning to keep the product away from children | 17 (85) | Store in a securely locked cabinet away from children. |
| Warning against use if pregnant/breastfeeding | 13 (65) | WARNING: USE BY PREGNANT OR BREASTFEEDING WOMEN, OR BY WOMEN PLANNING TO BECOME PREGNANT, MAY RESULT IN FETAL INJURY, PRETERM BIRTH, LOW BIRTH WEIGHT, OR DEVELOPMENTAL PROBLEMS FOR THE CHILD. |
| Warning against driving after using the product | 17 (85) | Marijuana impairs concentration, coordination, and judgment. Do not operate a vehicle or machinery under its influence. |
| Warning about potentially delayed effects of product | 16 (80) | CAUTION: When eaten or swallowed, the intoxicating effects of this product may be delayed by 2 or more hours. |
| Warning about physical health risks of smoking/vaping product | 6 (30) | Marijuana smoke contains carcinogens and can lead to an increased risk for cancer, tachycardia, hypertension, heart attack, and lung infection. |
| Warning about physical health risks general to cannabis use | 8 (40) | There is limited information on the side effects of using this product, and there may be associated health risks. |
| Warning about mental health risks of any product use | 2 (10) | Warning: Frequent and prolonged use of cannabis can contribute to mental health problems over time, including anxiety, depression, stunted brain development and impaired memory. |
| Warning about risk of psychosis for high potency products | 2 (10) | This is a high potency product and may increase your risk for psychosis. |
| Requirement for minimum font size of text | 13 (65) | Text must be no smaller than size 6 font, bolded, legible, unobscured, and visible to the customer. |
| Requirement that warning must contrast sufficiently with the background | 4 (20) | Be displayed in a bright yellow box as to stand out from other labeling requirements. |
| Requirement for rotating warning | 2 (10) | At least 1 of a selection of warning statements rotated quarterly on an alternating basis. |
| Requirement for the warning to appear on front of packages | 0 (0) | NA |
| Number of characters (without spaces) | 296 (87–713) | NA |
| Number of words | 57 (17–141) | NA |
Note. The sample size was n = 20 states. NA = not applicable.
RESULTS
Themes in required warning label content varied widely across states. Most states required warnings to keep the product away from children (85%) and against use if pregnant or breastfeeding (65%). Most states also required a warning against driving after using the product (85%; though no states specified how long to wait) and required a warning about potentially delayed product effects (80%; with the timing of stated delays ranging between 2 to “4 or more” hours). Less than one third of states required a warning about the health risks specific to smoking or vaping (30%), while 40% of states required a warning about health risks general to any cannabis use (often vaguely worded). One state required a warning about harms to the developing brain, specifically for those aged 25 years or younger. Two states required a warning about mental health risks (10%) on all cannabis products and 2 states required a warning about psychosis on high potency THC products (10%).
Characteristics required of cannabis warning labels also varied widely across states. More than half of states required text to be a minimum font size (65%), ranging from 6- to 8-point font. Four states had requirements for contrasting text, border, or background (20%). Two states required periodically rotating warning messages to supplement permanent core messages (10%). No states required warnings to appear on the front of packages (0%). Warnings contained a mean of 296 characters (range = 87–713), excluding spaces, and 57 words (range = 17–141).
DISCUSSION
Our study examined US state nonmedical cannabis warning label regulation content and characteristics, allowing for a comparison between state regulatory practices, existing evidence in cannabis effects and cannabis warning efficacy, and best practices in warning label design.
When considering the warning content that states required on cannabis product labels, our study revealed mixed alignment with evidence related to cannabis effects and cannabis warning efficacy. Areas of highest alignment with known risks of cannabis use included messages related to children, pregnancy and breastfeeding, impaired driving, and delayed effects of edible products.3,4 However, despite substantial evidence of an association between cannabis use and the development of mental health problems,3 as well as evidence that messaging about mental health on cannabis warning labels can be highly efficacious,4 85% of states did not require a warning about mental health risks or psychosis on any type of product. Evidence of higher mental health risk for consumers of high potency products,8 combined with evidence that legalization is associated with increased use of high potency products,9 further supports the rationale for the requirement of warning content related to mental health risks across US states.
Our study also identified several opportunities to improve the design of cannabis warning labels. Canada’s cannabis warning label regulations reflect best practices in warning label design, requiring periodically rotating health warnings on the principal (front) side of packages in contrasting colors in a font size larger than or equal to that of the brand name.4-6,10 In our analysis, only 2 states required rotating health warnings, no states required warning labels to be on the front of packaging, few states required contrasting colors, and while some states had minimum font sizes, they were small.
Several factors complicate the development of effective cannabis warning label regulations in the United States. The wide variety of cannabis products (e.g., varied potency, content, mode of administration) creates a complicated patchwork of varying health risks that may necessitate different warnings for different products. Furthermore, the evidence on cannabis health effects is still emerging. More research is needed on (1) short- and long-term effects of cannabis (and how these vary by product) 11 and (2) real-world evidence on how cannabis warning labels can be better designed in the United States. The development of strong evidence to back state nonmedical cannabis warning label regulations is particularly critical when considering potential First Amendment challenges that will likely accompany the spread of cannabis legalization and commercialization.12
This study is limited in that both the market and policy landscape of nonmedical use cannabis is rapidly evolving at the state level. While these findings provide a snapshot of regulatory practices in March 2024, continued monitoring and updating is necessary.
PUBLIC HEALTH IMPLICATIONS
In the absence of federal legalization, states that legalize nonmedical cannabis face a daunting regulatory design task with limited evidence to guide their path.11 However, they also have a unique opportunity to bake evidence into regulation, setting precedent in favor of public health amid the growing business interests that accompany the spread of legalization.12 Product warning labels are a key regulatory tool in empowering cannabis consumers to make informed decisions about cannabis use.4–6 This paper identifies actionable opportunities for states to improve the alignment of their cannabis warning label regulations with evidence that has been generated so far.
ACKNOWLEDGMENTS
This project was funded by an internal planning grant from the UNC Center for Health Promotion and Disease Prevention.
The authors thank the US state cannabis regulatory agencies for verifying their state’s current cannabis regulations.
Note. The content is solely the responsibility of the authors and does not necessarily represent the official views of the UNC Center for Health Promotion and Disease Prevention or US state cannabis regulatory agencies.
CONFLICTS OF INTEREST
The authors have no conflicts of interest to disclose.
HUMAN PARTICIPANT PROTECTION
No protocol approval was necessary because this study did not involve human participants.
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