INTRODUCTION

The prevalence of cannabis use is rising among the US population.1 As cannabis continues to be legalized throughout the USA, people are turning to the internet and social media for information about its potential health benefits.2,3 In this study, we characterize internet claims about the health benefits of cannabis use in the lay press and evaluate the evidence base supporting those claims.

METHODS

We performed a cross-sectional study of internet claims focused on the health benefits of cannabis use. We extracted information on claims from two different sources on June 15, 2019: (1) We searched Google for “marijuana benefits,” “weed benefits,” and “marijuana health.” Our sample includes the top ten lay webpages from each Google search. (2) We searched Buzzsumo, a social media analyzer tool that calculates online engagement with news articles, to measure each article’s engagement by its number of likes, shares, and comments on social media sites. We used the terms: “marijuana benefits OR cannabis benefits OR weed benefits,” and “marijuana health,” restricting our search to articles published in the previous 2 years (2017–2019). We excluded articles irrelevant to the potential health benefits of cannabis use, and only included high-impact articles (over 10,000 engagements) because they had the most reach with an online audience. Internet links to the scientific literature were not included since the focus of this analysis was to characterize information available to the public in the lay press. Two reviewers (NL, MG) independently reviewed webpages and articles to extract and categorize claims about the health benefits of cannabis use and tally the frequency of each claim category. Two investigators with expertise in cannabis evidence review (SK, DK)4,5 evaluated the literature published before November 2019 to determine claim validity based on available evidence. The two investigators searched Medline to first identify published systematic reviews. For claims with no relevant systematic reviews, randomized controlled trials were sought. Health claims were compared to the existing trial evidence and categorized as not true, partly true, and true. Disagreements were resolved by discussion.

RESULTS

The Google search produced 20 unique lay webpages/articles, and the Buzzsumo search produced 116 high-impact articles. We excluded 16 articles for irrelevancy (e.g., focus on cannabis policies instead of use) and 15 for inaccessibility (expired webpages), leading to 105 total sources. We found 275 individual claims regarding the health benefits of cannabis use in Google sources, and 192 claims in Buzzsumo articles. The 467 individual claims in our sample comprised 81 distinct clinical categories (Fig. 1). Of the 81 categories, 65 (80.2%) were not true, 7 (8.6%) were partly true, and 4 (4.9%) were true; 5 (6.2%) were unable to be assessed due to being too broad or vague (e.g., anti-inflammatory or digestive function). Table 1 summarizes the 10 most common categories of claims. Claims regarding the benefit of cannabis in the treatment of pain were the most common. Other common claims included the efficacy of cannabis for glaucoma, depression, nausea, muscle spasms, Parkinson’s disease, and cancer therapy, and as an alternative to opioids or reducing opioid dependence. Claims classified as “Not true” related to general pain, cancer, anxiety, post-traumatic stress disorder, neuroprotection, and Alzheimer’s disease. The remainder of claims (among the top 10 common) were true (treatment of chemotherapy-induced nausea/vomiting and spasticity from multiple sclerosis) or partly true (treatment of seizures and sleep) (Table 1).

Figure 1
figure 1

Sample construction. a81 Clinical categories: general pain, cancer pain, nerve pain, migraines, fibromyalgia, epilepsy/seizures, anti-nausea/vomiting from chemotherapy, anti-nausea, cancer treatment, anxiety, multiple sclerosis, reduce muscle spasms, sleep, Alzheimer’s disease, alternative to opioids, reducing opioid dependence, neurogenesis, neuroprotective, appetite stimulant (general), eating disorders, appetite stimulant for people w/ AIDS, cachexia, improves weight loss for cancer patients, obesity, Crohn’s disease, ulcerative colitis, irritable bowel syndrome, glaucoma, depression, post-traumatic stress disorder, schizophrenia, obsessive compulsive disorder, ADHD, emotional, mood, and cognitive regulation, phobias, other mental health/mood disorders, dementia, autism spectrum disorder, leukemia, brain cancer, breast cancer, bladder cancer, lung cancer, pancreatic cancer, colon cancer, prostate cancer, skin cancer, treating movement disorders (general), amyotrophic lateral sclerosis, Parkinson’s disease, Tourette’s syndrome, respiratory, asthma, cardiovascular, blood sugar, chronic heart failure, hypertension, heart attack, stroke, treating alcoholism, quitting smoking, treating marijuana abuse, quitting other drugs, anti-inflammatory, arthritis, alcohol, sexual health, sexually transmitted diseases, female reproductive health, skin health, diabetes, hepatitis C, lupus, liver, malaria, bones, cartilage, degenerative disc disease, immune system, spinal cord injury, palliative care, digestive function.

Full size image
Table 1 Top 10 Most Common Clinical Categories of Claims, Examples of Individual Claims Related to that Category, and Review of Trial Evidence
Full size table

DISCUSSION

We found that less than 5% of the internet claims about the health benefits of cannabis use were proven to be true based on available evidence. The inadequacy of the current evidence enables the proliferation of untrue claims, which inform the current social discourse on the health benefits of cannabis. More studies on the health effects of cannabis are needed to better inform the public and health care providers. Patients and providers should be cautious consumers of health information on the internet given the current state of the evidence and proliferation of false claims.