Weed cream. THC lotion. CBD salve. They go by many names, and there is a lot of interest and hope in the dermatological community that marijuana—or cannabis—may provide an alternate treatment pathway for a variety of skin diseases, especially atopic dermatitis (AD).
As of 2020, 33 states and Washington, D.C., have legalized some type of marijuana programs. These programs range from full legalization for recreational use, to medical use only, or decriminalization.
Dermatologists across the country, particularly in states where cannabis has been made legal, are inundated with questions such as, “Will tetrahydrocannabinol (THC) or cannabidiol (CBD) topicals work for my skin condition?”
Unfortunately, the fractured regulatory market of cannabis topicals makes it challenging for doctors, consumers and even regulators to understand the benefits and risks. In this article, we’ll take a look at the science and potential benefit behind the molecules found in marijuana for dermatological conditions.
The science behind medical marijuana
Marijuana, derived from the plant Cannabis sativa, is one of the oldest and most widely used drugs worldwide. Of the more than 60 agents in marijuana, only THC has intoxicating effects. This has not only contributed to its illicit status in the medical field, but has also hindered research on its health benefits.
Cannabis, marijuana and hemp are often lumped together as a single plant. Cannabis or marijuana, and other related colloquialisms such as weed, pot and ganja, are used to describe THC-rich cannabis varieties that, when used, make people feel intoxicated.
Hemp is legally defined as a cannabis plant having less than 0.3 percent THC, so it is often termed a “low THC variety.” Marijuana is legally defined as cannabis having greater than 0.3 percent THC. If that wasn’t complicated enough, marijuana and hemp are regulated separately, with less regulatory oversight for hemp.
Aside from the array of major cannabinoids, a variety of other molecules are produced by both hemp and marijuana, including terpenes, which create the unique scent from one strain of plant to another, and flavonoids, which contribute to the pigment of the plant.
Marijuana has relatively higher concentrations of cannabinoids, terpenes and other molecules leading to its intense scent and coloring, and these constituents interact with the human body through the endocannabinoid system, which then interacts with other physiological systems.
The relatively recent discovery of cannabinoid receptors throughout the human body has led to more open discussion on their role as a viable treatment for diseases.
Not all cannabinoids make people feel “high”
Best known as the main chemical agent in marijuana, THC is responsible for its psychoactive properties, which has stigmatized the plant in the minds of many people. However, cannabinoids are a diverse group of compounds that have great potential to treat many medical conditions without making the patient feel intoxicated.
There are five major cannabinoids found in marijuana:
- cannabidiol (CBD)
- cannabichromene (CBC)
- cannabigerol (CBG)
- delta (9)-tetrahydrocannabinol (THC)
- cannabinol (CBN)
Since the first human cannabinoid receptors were discovered in the late 20th century, many applications for these extracts of the cannabis plant have been found.
Of particular interest in AD are these respective cannabinoids’ anti-inflammatory and anti-itch properties. Additionally, the high safety profile and relatively low levels of cannabinoids needed to have an effect on the skin result in low systemic absorption into the bloodstream, which eliminates the risk of potential intoxication from THC.
How does cannabis help eczema?
It has long been observed that cannabinoids possess anti-inflammatory, antimicrobial and anti-itch qualities, but not until recently has high-quality research been published to understand the physiological effects underlying these anecdotal reports.
Dr. Henry Granger Piffard, MD (1842-1910), was one of the founders of American dermatology. He was the founding editor of the Journal of Cutaneous and Venereal Diseases, known by its current name, JAMA Dermatology.
The first textbook of dermatologic therapeutics was also written by Piffard. In it he notes, “a pill of cannabis indica at bedtime has at my hands sometimes afforded relief to the intolerable itching of eczema.” Since then, there have been myriad studies published on the potential benefits of cannabinoids in skin conditions.
Many features of AD contribute to itch, particularly dry skin, histamine release and sensory nerve fibers. Cannabinoids, however, have a powerful anti-itch effect. There are receptors in the skin that interact with cannabinoids that could reduce the symptoms and appearance of AD. These effects happen through a constellation of interactions between phytocannabinoids and our endogenous cannabinoid system.
Another way cannabinoids hold promise as a treatment are through management of Staphylococcus aureus colonization, which is both a complication and a driving factor of AD.
The antimicrobial characteristics of cannabinoids have been referenced since the 1980s, but a more detailed analysis of individual cannabinoids found that all five major cannabinoids showed potent activity against a variety of S. aureus strains.
What does this mean? Cannabinoids have an anti-microbial effect, but more testing is needed to understand the risks and benefits of cannabinoids in dermatology.
Cannabinoids also exhibit anti-inflammatory properties. Researchers demonstrated that topical THC suppresses allergic contact dermatitis in mice by activating CB1 receptors. Other molecules, similar to those present in cannabis, have also demonstrated significant anti-pain properties in rat models.
There are reports of direct improvement of AD with topical cannabinoids. A recent study demonstrated that a molecule interacting with the endocannabinoid system inhibited mast cell activation. Mast cells are immune cells that release histamine when activated, which leads to intense itching and inflammation.
In a human trial for patients with AD, an endocannabinoid cream improved severity of itch and loss of sleep by an average of 60 percent among subjects. Twenty percent of subjects were able to stop their topical immunomodulators, 38 percent ceased using their oral antihistamines, and 33.6 percent no longer felt the need to maintain their topical steroid regimen by the end of the study.
The future of cannabis creams for eczema
For eczema patients, extra caution should be taken because a variety of known irritants are very prevalent in many “weed creams”. The indiscriminate addition of terpenes that can be irritating are often included in these formulations.
Special attention should be given to choosing a product to ensure that only non-irritating terpenes are included in the formula. Topicals should be chosen based on the profile of ingredients that are known to reduce pain, inflammation and irritation for the skin, not formulations that may have been developed for muscle and joint pain. Additionally, excess solvents from the manufacturing process could also be present.
With 29 states and counting having some form of legalization of medical marijuana, this means that there are at least 29 state regulatory schemes.
To further complicate things, hemp-based products (low THC varieties) can be purchased online and have virtually no regulatory oversight for potency, consistency or contaminants including pesticides and metals.
Incorrect dosing and inaccurate labeling has plagued the industry since inception. A recent study by Penn State University determined that up to 70 percent of online CBD products are inaccurately labeled.
Until clinical data is created for specific products, the best advice may be to pay special attention to the ingredient lists and make sure that products are tested by a third-party laboratory instead of the manufacturer themselves. State markets with dispensaries typically regulate testing, which is an added consumer protection compared to purchasing a product on the internet.
Cannabinoids represent an exciting prospect for the future of AD therapy. With measurable anti-itch, anti-pain, anti-microbial and anti-inflammatory properties, the effect of cannabinoids in patients with AD has already begun to be demonstrated.
Disclaimer: The information provided in this article has not been evaluated or approved by the U.S. Food and Drug Administration (FDA). It is not medical advice. If you are considering making any changes to your lifestyle, diet or nutrition, you should consult with your doctor or other health care provider. Conflicts of interest statement: Helena Yardley, Ph.D. and Jon Fernandez, SVP are employees of CQ Science. Peter Lio, M.D. is on the advisory board of CQ Science.
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