ABSTRACT: Importance:Use of cannabidiol (CBD) has markedly increased in the past 5 years, concurrent with marketing claims that over-the-counter CBD can be used to treat almost any health condition. However, the reasons why individuals use CBD remain unclear. Objective:To assess whether individuals are using CBD for diagnosable conditions that have evidence-based therapies. Design, Setting, and Participants:This case series assessed claimed treatment applications reported by CBD users in public testimonials shared on the Reddit forum r/CBD. The r/CBD forum was selected because it includes a large, naturally occurring sample of 104?917 registered individuals who publicly discuss their experiences using CBD. All r/CBD posts were obtained from January 1, 2014, through August 31, 2019. A random sample of posts was drawn (n?=?3000) and filtered to include posts in which self-identified CBD users testified why they take CBD (n?=?376). Exposures:Self-reported use of CBD for medicinal purposes. Main Outcomes and Measures:Cannabidiol testimonials were divided into 11 subcategories corresponding with the condition's medical subspecialty and 2 subcategories corresponding with wellness benefits. Posts were allowed to receive more than 1 label. Results:Of the 376 posts labeled as testimonials, 90.0% (95% CI, 86.8%-92.8%) of testimonials claimed that CBD treated the individual's diagnosable conditions. Psychiatric conditions (eg, autism or depression) were the most frequently cited subcategory, mentioned in 63.9% (95% CI, 59.0%-69.1%) of testimonials, followed by orthopedic (26.4%; 95% CI, 21.8%-31.1%), sleep (14.6%; 95% CI, 11.3%-18.5%), and neurological (6.9%; 95% CI, 4.4%-9.6%) conditions. Testimonials also claimed that CBD treated gastroenterological conditions (3.9%; 95% CI, 1.9%-6.1%), as well as addiction, cardiological, dermatological, ophthalmological, oral health, and sexual health conditions (<2.0% each). By contrast, just 29.5% (95% CI, 24.8%-34.2%) of testimonies claimed any wellness benefit, with most citing mental wellness (eg, "quieting my mind") (29.5% [95% CI, 24.2%-34.4%]); 1.4% (95% CI, 0.3%-2.8%) claimed a physical wellness benefit (eg, "exercise performance"). Conclusions and Relevance:The findings of this case series suggest a need for regulation of factors associated with CBD being used to treat diagnosable conditions, engagement of health care professionals with patients on their potential CBD use, and implementation of public health campaigns that encourage the public to seek treatment advice from health care professionals regarding evidence-based therapies.