The market for hemp-derived topical cannabinoid products has seen substantial growth since 2018, but research on these products is lacking. This case series study tested topical cannabinoid products representative of those available throughout the US for CBD and THC content. Although there are few to no clinical data to inform whether commercial topical cannabinoid products such as those examined here can deliver THC and CBD to users, preclinical studies^7,8,9,10 and clinical research with a pharmaceutical-grade CBD gel^11,12 have shown that cannabinoids can penetrate the skin and enter systemic circulation when applied topically via some formulations. Thus, our findings may have important implications for consumers of topical cannabinoid products.

Most products were inaccurately labeled for CBD. Products with lower CBD than advertised may be less likely to elicit the desired medical benefits. Products with more CBD than advertised may be a health concern given the potential for adverse effects from CBD (eg, liver toxicity) and drug-drug interactions between CBD and common prescription medications.^13,14 The labeled amount of CBD was usually expressed on the basis of the total contents of the product (eg, full lotion bottle) as opposed to the dose intended for each application. This labeling practice, in combination with vague or unclear application instructions, may contribute to inconsistent dosing and confusion among consumers.

THC was detected in 35% of products, most of which did not mention THC on the label or claimed to be THC free. Although THC concentrations were always under the legal limit for hemp (<0.3%), many products contained amounts of THC (up to 100 mg) capable of producing substantial intoxication when administered through other routes (eg, oral, smoked, or vaporized). That said, we measured the total amount of THC in these products and it is unlikely that someone would use an entire container on a single occasion. Controlled research is needed to determine whether topical products similar to those examined here can deliver THC to humans at levels capable of producing intoxicating effects. Research is also needed to determine whether topical products with THC can produce positive drug tests for cannabis, particularly when used repeatedly, as has been observed for hemp-based oral CBD products with low amounts of THC.¹⁵ Such research can inform whether individuals should abstain from using these products if they are drug tested for their occupation or other reasons. Ideally, future clinical studies should investigate a variety of topical products to elucidate whether product formulation is associated with cannabinoid absorption or acute drug effects.

The products examined often included therapeutic or cosmetic claims largely unsubstantiated by empirical evidence. For example, 22% of products claimed to be effective for pain relief, yet the FDA has not approved cannabinoid products (including topicals) for pain. Misleading claims may result in individuals using poorly regulated and expensive cannabinoid products instead of FDA-approved products that are established as safe and effective for a given health condition.