In contrast, transdermal products deliver CBD in a manner that penetrates through the upper barriers of the skin and into the bloodstream. Animal studies have shown that CBD administered as a transdermal gel makes its way into the bloodstream and increases plasma levels of the cannabinoid.
How cannabinoids interact with the skin
Upon applying a cannabinoid product to their skin, people often assume the cannabinoid enters their bloodstream. But just how true is this supposition? Well, it really depends. CBD and other cannabinoids can be applied to the skin in two distinct methods: topical and transdermal.
Several studies have investigated the effects of cannabinoids on common dermatological issues. For example, a study in the Journal of Dermatological Science looked at the effects of this family of molecules against keratinocyte hyperproliferation, which is associated with
red, flaky, and scaly skin.
A review published in Trends in Pharmacological Sciences states that the endocannabinoid system of the skin plays a key role in several crucial processes. External cannabinoids share a similar structure to those found in the body, and also target the same receptor sites.
If you (like me) feel like your CBD cream is truly having an effect, it’s likely unrelated to the CBD itself. And because there are plenty of other pain management options out there that we know more about—including medical cannabis—it’s important to talk to a health care provider to make sure you’re not overlooking something else that might be more helpful.
The first thing to be aware of is the amount of CBD that a product claims to contain. Because the studies we have about CBD and pain all looked at systemic administration rather than truly local, we don’t really know what the correct dose would be when applied locally. It’s tempting to go for the highest amount you can find, but it’s really up to you since we don’t even know where to start.
In fact, the most compelling research they found for using cannabinoids for pain came from a large review and meta-analysis published in JAMA in 2015. For the study, researchers looked at results from 79 previous studies of cannabinoids and various medical conditions, including chronic pain. However, of those studies, only four involved CBD (without THC)—none of which were looking at pain. So although we might assume that CBD is doing something to help address pain—according to the studies involving the whole cannabis plant—we don’t have great evidence to prove it.
So…is CBD cream just an expensive placebo?
Why does the body have receptors for compounds in cannabis? Well, it doesn’t exactly. Cannabinoids like THC and CBD are similar enough to compounds that your body naturally makes, called endocannabinoids, that they can interact with this system. Normally, the endocannabinoid system is thought to play a role in a variety of functions in the body, helping to regulate things like parts of the immune system, the release of hormones, metabolism, and memory.
That said, we don’t always know exactly what’s in the CBD products out there due to a lack of regulation. Until recently, CBD was regulated as a Schedule 1 substance, meaning that the federal government believed it had a high potential for abuse and no accepted medical value. But the FDA approval of Epidiolex last year and the passage of the Farm Bill in December 2018 changed things by lifting the federal ban on commercial hemp production (hemp also contains CBD in lower amounts than cannabis). But it also made things more confusing because we’re still waiting on actual CBD regulations from the FDA. In the meantime, companies are treating hemp-derived CBD as if it’s perfectly legal, Dr. Tishler says.
And even though the lotion was applied topically in the rat study, it wasn’t applied locally to the knee. Instead, the researchers were really using the topical application to get it into the rats’ bloodstream, or what’s called systemic administration. But you’d likely need a different dose for it to be effective locally (if you applied it just to your aching shoulder, for instance) in a human. We have no idea what that dose should look like.
It’s also important to remember that, although generally benign, side effects have been reported with some forms of CBD. For instance, oral CBD taken in the large amounts that have shown some limited promise in helping with anxiety issues may come with side effects, such as diarrhea, reduced appetite, fatigue, and interactions with other drugs you might be taking, specifically blood thinners, Cooper says.