Could cannabis help treat psoriasis? What the evidence says

It’s been nearly eight years since cannabis was legalized in Canada, and interest in its potential therapeutic applications, including in dermatology, remains high.In June, during the Canadian Dermatology Association's annual conference in Calgary, dermatologist and researcher Dr. Mark Kirchhof delivered a talk detailing some of his research findings regarding cannabis and the potential promise it holds to treat skin conditions like psoriasis.“I learned how to write prescriptions for cannabis . . . and that led down a journey of investigation and evaluation of cannabis and cannabinoids for a variety of skin diseases,” he said.In a 2022 study published in the Journal of Cutaneous Medicine and Surgery, Dr. Kirchhof and his team surveyed 430 patients across Canada and found that 24% of respondents had used cannabis topically, with the most common dermatological purposes being for atopic dermatitis, acne and anti-aging. Psoriasis was ranked further down this list, but of the patients who used topical cannabis to treat the condition, 30% indicated improvement, while 56% indicated it was neutral and 10% said their condition worsened.Health Canada, for its part, has not approved cannabis as a treatment for any medical condition. Yet, its guide for healthcare professionals on medical uses for cannabis, the agency noted cannabis “may have therapeutic value in the treatment of certain inflammatory skin conditions” such as psoriasis, pruritus, dermatitis and acne, but noted the possibility for some cannabinoids to trigger “adverse skin reactions.”In his most recent study, published this summer also in the Journal of Cutaneous Medicine and Surgery, Dr. Kirchhof and his team conducted a gene analysis of psoriasis patients to identify potential therapeutic targets. Among their findings, cannabinoid 2 (CB2) receptors were found to be “notably up-regulated” in skin samples with psoriasis compared to healthy controls. In patients with psoriasis, CB2 was also shown to be more up-regulated in psoriatic lesional skin than is non-lesional skin.“Previous studies have found increased expression of the CB2 receptor in mice with psoriasis. We are the first to report it in human tissue,” Dr. Kirchhof said.Other cannabinoid-interacting receptors affected in psoriatic skin samples included the alpha, gamma and delta types of peroxisome proliferator–activated receptors (PPAR), as well as some serotonin receptors.“A population-based cohort study did reveal that the use of SSRIs in patients with psoriasis was associated with a decreased need for systemic treatments, which I thought was also very interesting,” Dr. Kirchhof added.During the Q&A session, an attendee asked whether patients might get a more “reliable” result if they were able to get a product with the cannabinoids isolated, compared to using the natural product.In response, Dr. Kirchhof said patients would likely have a “bigger, better response” with a synthetic cannabinoid.“We have lots of examples throughout medical history where we take the plant product, extract the important chemical, and manufacture the equivalent.”

Could cannabis help treat psoriasis? What the evidence says

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