Evidence for cannabis products in dermatology only skin deep

The use of cannabis-based skin products is ever more popular, but how useful they are for dermatologic conditions is a mixed and complex story with most products having little to no evidence for their usefulness. But their use is common and on the rise. According to a 2019 marketing report from Grand View Research, the global cannabinoid (CBD) skin care market size was valued at $234.1-million US in 2018 and is expected to grow 32.9% from 2019 to 2025. While there is some evidence for specific cannabinoids being helpful for a handful of conditions, most skin conditions see no benefit from cannabis products and, in some cases patients can actually develop skin problems from cannabis such as contact dermatitis, according to said Dr. Mark Kirchhof, head of the division of dermatology at the University of Ottawa. He spoke at the recent annual meeting of the Canadian Dermatology Association. He noted that ‘cannabinoid’ “refers to any chemical, regardless of structure or origin, that binds cannabinoid receptors of the body and brain and that have similar effects to those produced by the Cannabis plant.” Read: Medical cannabis may have role in decreasing opioid use: study Two types of CB receptors (CB1 and CB2) occur throughout the body, with one or both occurring in parts of the nervous system, various organs, in the lymphatic and immune systems, upper airway, bone, all the layers of the skin, and other areas. A review article published in 2018 in the Journal of Cutaneous Medicine and Surgery coauthored by Dr. Kirchhof, explained that the body produces its own cannabinoids, endocannabinoids, which are endogenous lipid-based retrograde neurotransmitters which bind to cannabinoid receptors. The receptors play roles in everything from pain modulation, neural functions such as motor coordination and various physiologic functions. But overall, “the cannabinoid system in our body is poorly understood.… The problem is the cannabinoid system itself is pleiotropic. There are different types of cannabinoids and different types of receptors. That makes the system hard to understand,” he told the Medical Post in an interview. In the skin, CB1 and CB2 receptors are found in epidermal, keratinocytes, cutaneous nerves, sebaceous cells and more. They appear to help regulate keratinocyte activity, but also play roles in diseases such as psoriasis which is characterized by keratinocyte over-proliferation and skin inflammation. There are still a lot of unknowns, yet there are hundreds of cannabis-based products on the market making claims about being able to treat a wide variety of dermatologic conditions. Products are in the form of topicals, sublingual administration, oils and inhaled. For the vast majority there is scant evidence that these products do anything helpful. Some promising evidence But a small number of conditions do have some evidence. In the U.S., medical marijuana has been approved for use for pain, lupus, nail-patella syndrome, psoriasis, Ehlers-Danlos syndrome, Lyme disease, neurofibromatosis and Sjogren syndrome. But while there are compelling reasons they can help at least some patients, with these and other conditions, the evidence isn’t very strong, Dr. Kirchhof said. Studies that have been published are highly variable “and range from case reports to in vitro or lab-based evidence. There is a lack of well-controlled trial-based data and comparisons to other approved drugs,” he said. The one area that has the most research behind it is for the treatment of pain. Cannabis plants contain at least 483 chemicals, 60 to 70 of which are cannabinoids as well as other compounds that also have biologic effects. There are varying combinations and ratios of these compounds in the wide variety of cannabis plants out there. Many of the compounds have not been studied, and how they each affect people is unknown. On top of that there are variations between products on the market, meaning there is no real standardization. They can also interact with other medications people are using. Studies conducted by Dr. Kirchhof and colleagues suggest between 10% to 25% of the Canadian population have used cannabinoid products to try to treat skin conditions. In a study Dr. Kirchhof and colleagues recently conducted, patients have used topical cannabis for everything from eczema, acne, sunburn, itch and even melanoma. The same study found most patients reported neutral to no effect, although 7.2% to 27.8% reported they experience some level of efficacy depending on the indication. Unfortunately, advertisements for the products make a wide variety of unsubstantiated claims about what cannabis products can do. Some claim products can cure or treat cancer including melanoma, “and that is a potentially dangerous thing to tell consumers,” he said. There are several dermatologic conditions where cannabinoids have not yet been approved for use in the U.S., but basic-science and small studies suggest there may be promise. These include acne, atopic dermatitis, hidradenitis suppurativa, Kaposi’s sarcoma, and melanoma (one lab study suggests THC may help initiate melanoma cell apoptosis, but there are no clinical data). More basic research along with randomized, controlled trials using standardized products is needed. At the same time, cannabinoid products can have dermatologic side-effects including arteritis, pruritus, urticaria, and contact dermatitis. Regular users have an increased risk of oral cancers. In his own practice, Dr. Kirchhof has treated contact dermatitis in workers from a cannabis product plant. For other patients, he sometimes writes prescriptions for medical cannabis—but not as first-line treatments. The scripts are generally for patients who have failed other treatments. “If they are still suffering after exhausting other allopathic treatment options, then I work with them to try to find alternatives,” he said. His experience has been with systemic cannabinoids for hidradenitis suppurativa (for pain control and sleep); pruritus without primary lesions and lymphomatoid papulosis. He has prescribed systemics or topicals for atopic dermatitis, and topicals for psoriasis. The experience has been mixed, with some patients having notable responses, but little to effect on others. He suggests all physicians should ask if their patients are using cannabis products. Try to be informed about the evidence and look at the peer-reviewed scientific literature.

Evidence for cannabis products in dermatology only skin deep

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