Anyone who has paid any attention to the cannabis “wellness” industry in recent years – whether through state medical and recreational programs or the free-for-all national CBD market – will be familiar with cannabinoid-infused topicals marketed to treat minor aches and pains. Because they’re easy to use and non-intoxicating, these products may serve as familiar, low-risk entry-points for elderly, wary, or cannabis-naive individuals into the wider world of cannabis products.
Cannabis-infused salves, lotions, and the like work because cannabinoid receptors CB1 and CB2 – as well as secondary targets including TRP (“trip”) channels, PPARs (nucleus receptors), and serotonin receptors – are abundantly expressed in skin cells.12 Topically applied cannabinoids can bind directly with these receptors and thus reduce local inflammation and pain.
But properly formulated cannabis topicals may be able to do more than just that. For decades, researchers have studied cannabinoids’ ability to treat clinical skin conditions like acne, ulcers, and dermatitis. In the skin, as elsewhere, the endocannabinoid system works broadly to maintain balance, proper functioning, and immune response, including through the synthesis of the endocannabinoids anandamide and 2-AG.3 It’s even possible that cannabinoids taken internally, and not simply via a localized topical, may be able to help – especially if a condition is more widespread.
While skin disease remains a relatively little-known indication for cannabis use, and certainly demands more specialized attention than your standard soothing balm, numerous recent papers suggest it’s an area well worth exploring.
Cannabinoids for Inflammatory Skin Diseases
To start, consider a recent article in the journal Pharmaceuticals4 that examines previous research into cannabis-based medicines for inflammatory skin diseases such as acne,5 eczema, dermatitis, and psoriasis. The Portugal-based authors review 29 studies published between 2003 and 2021, 13 of which used human subjects and the rest cell and animal models. None of the human studies involved oral intake of cannabinoids per se, though one did find that increased consumption of hemp seed oil, but not olive oil, was associated with reduced symptoms of atopic dermatitis. The authors of the original study attributed this to the high concentration in hemp seed oil of polyunsaturated fatty acids, which are endocannabinoid precursors.
Topically delivered active ingredients in the other human studies cover quite a bit of ground: CBD, CBG, THC, hemp seed oil, the endocannabinoid anandamide, the cannabinoid-like endogenous compound palmitoylethanolamide (PEA), and the synthetic research cannabinoid HU210.
Given the mostly positive results of these studies and additional preclinical work, the review authors conclude that not only are cannabinoid-infused topicals well tolerated, but they show particular promise in the treatment of psoriasis, atopic dermatitis, and contact dermatitis.
“The studies reviewed here suggest that cannabinoids and cannabinoid receptor modulators can have a therapeutic action in several inflammatory skin diseases, due to their antiproliferative, immunomodulatory, and anti-inflammatory actions,” the authors conclude. “However, to further explore such possibilities, our knowledge of the cutaneous cannabinoid system must expand.”
The Skin Endocannabinoid System
Another recent review, published in the journal Cells in December 20226 by researchers at Germany’s Rostock University, takes an even broader look at the potential of cannabinoids to treat diseases of the skin. It begins with an illuminating overview of the endocannabinoid system’s role in a bevy of skin functions and processes.
Simply scanning the list may foster a deeper appreciation not only of the endocannabinoid system, the body’s master regulator, but also of skin itself, the body’s largest organ. From top to bottom, the authors’ compendium of ECS-mediated skin functions includes:
- melangenesis (the production and distribution of melanin, critical to protecting the skin from UV radiation and oxidative stress)
- wound healing
- cutaneous barrier function (including both “inside-out” protection against water loss and “outside-in” protection from external threats like infectious agents, chemicals, and allergens)
- sebocyte biology (or the function of sebaceous glands, which produce an oily substance called sebum, the overproduction of which can cause acne)
- hair follicle biology and the control of hair growth
- effects of photoexposed epithelium (for example, the authors suggest that CBD may reduce the harmful effects of UV radiation)
- cutaneous pain, or pain transmission and perception in the skin
- keratinization (the process in which cells from beneath the skin are converted to keratin, a protein that helps form hair, nails, and the skin’s outer layer or epidermis)
- skin aging processes
The Sky’s the Limit?
Next, the study authors review existing clinical and preclinical evidence on the effects of cannabinoid treatment for a long list of skin diseases both common and obscure. These include allergic contact dermatitis, keratin disorders, scars and keloids, epidermolysis bullosa, pyoderma gangrenosum, acne, acute inflammation, androgenetic alopecia, eczema, atopic dermatitis, dermatomyositis, hidradenitis suppurativa, histamine-induced itch, postherpetic neuralgia, pruritus, psoriasis, systemic sclerosis, urticaria, and venous leg ulcers.
Suffice to say, they are thorough. After all this, their final take? “It can be summarized that cannabinoid compounds have great potential in the treatment of skin diseases, both as topical applications and as systemic medication.”
But stay tuned for more, they add: “Since there are indications of possible effects of cannabinoids in several skin diseases other than those studied in patients so far, it can be further assumed that the potential of cannabinoids is far from exhausted and that further indications will be tested in the coming years.”
More Evidence
In fact, two more papers too new to be cited in the Cells review further support its conclusion. A November 2022 article in Tropical Medicine and Infectious Disease7 reports – based upon laboratory evidence – that both THC and CBD “may serve as therapeutic agents or in co-administrated therapy” for cutaneous leishmaniasis, a vector-borne parasitic disease that causes skin lesions. This condition affects people in nearly 90 countries but is particularly prevalent in Morocco, where the authors are based.
And a January 2023 study in Advanced Skin and Wound Care8 finds that among 45 digital ulcer patients followed for one to two months, those randomly assigned to receive a CBD-infused topical treatment reported reduced pain, increased scores on a health questionnaire, and improved sleep relative to controls receiving a non-CBD topical.
Nate Seltenrich, an independent science journalist based in the San Francisco Bay Area, covers a wide range of subjects including environmental health, neuroscience, and pharmacology.
Copyright, Project CBD. May not be reprinted without permission.
Footnotes
