It’s touted for relaxation, sleep, pain, inflammation. . . you name it. You can get it in a tincture. You can get it in a gummie. You can get it in a salve. According to GQ, you can rub it all over your body! I’ve seen creams, balms, and salves for topical application recently on friend’s bathroom counters and in fellow-gym-goer’s bags. It’s great for pain, they say! For muscle relaxation! For inflammation! So I had to dig in to the state of CBD and ask: is topical CBD a safe and effective remedy for musculoskeletal aches and pains? Here’s what I found:
First, what the heck is this stuff? Scientifically, CBD is a non-euphoriant, anti-inflammatory analgesic with CB1 receptor antagonist and endocannabinoid modulating effects. It’s considered a minor phytocannabinoid. It can be sourced from hemp or other cannibis-family plants (like the classic marijuana plants you probably think of).
- CBD a miracle drug! At least. . . if you’re a rodent, or maybe a child with epilepsy. A scientific literature search using PubMed turned up a few studies in animals (it seems to help rats with lab-induced arthritis), and a few looking at some specific medical conditions (MS, IBD, a few rare genetic syndromes). A regular old google search, though, was an embarassment of riches, with top hits from sites “ministry of hemp”, “leafly”, and “healthyhempoil.com”— all touting the miracle effects of products for sale. Ruh roh, this sets off a few alarm bells.
- Now, to be fair, some of the reason research is sparse is that it’s legally complicated. NIDA restricts federal funding and also access to cannibis in clinical research. I mention this because the “absence of evidence” is a barrier here, and one that’s propped up by the guvmint. There are a total of 138 studies registered in clinicaltrials.gov (that’s not a lot— for reference, there are over 10,000 on insulin). The most common indication studied is childhood epilepsy. Some of these were for cannabis which included both THC and CBD. Delivery forms were oils/tinctures, vaporizers, and a spray used in the mouth. There were zero studies on topical or transdermal CBD.
OK, there’s not a lot of evidence, we get it. So, is it safe??
- Overall, the evidence suggests that the safety profile of CBD is well established. But there are still things we don’t know!
- In-vitro and rat studies suggest possible hormonal effects, but whether this translates to humans or to doses used is not known.
- There is the potential for drug interactions, particularly for drugs cleared by the liver.
- There is no long-term data.
The next question: topical application of CBD-containing products actually help with pain or inflammation?
- I repeat: there are no clinical studies about this. Zero, zilch, goose-egg. So what follows is mostly theoretical.
- NIDA reports that CBD in general has neuroprotective, alalgesic, anxiolytic, and anti-inflammatory effects.
- Research also demonstrates that CBD is absorbed transdermally, meaning that if you apply it to the skin, it is detectable in the bloodstream. However, there are lots of parameters that could impact absorption! It’s not known what effect the carrier, temperature, concentration, or other parameters might have. It also isn’t know whether there is a local effect (the area you apply it) vs. a systemic effect (throughout the body). Since it isn’t absorbred very well orally, transdermal administration is a good option.
- The rat study I mentioned above suggested that in rats (this is important, since you are not a rat), transermal application of CBD lead to pain relief— but they did not apply the medication to the affected joint. They just used the skin as a way to get the drug into the body. So they were not studying the local effect on the painful area, as some people assume they were.
So the answer is: CBD is likely safe, it’s in a legal gray area, and there’s no science about whether or not topical application has clinical benefit, and if so, through what mechanism.