Cannabidiol (CBD), relatively unknown just a few years ago in regard to its potential for improving health, is now one of the most popular supplements in the United State. In fact, OTC (over the counter) sales are projected to reach $20 billion in the next 5 years.
CBD is one of the many constituents of cannabis (i.e. marijuana) and is the active ingredient in the FDA approved prescription drug Epidiolex. Epidiolex is available as an oral solution and is used to treat two rare seizure disorders, Lennox-Gastaut and Dravet syndrome.
CBD products are widely available as dietary supplements, topicals, and infused-food and drinks, despite their questionable regulatory status. Topical CBD specifically, is most commonly used for pain, rashes and other associated skin conditions.
Unfortunately, there is no high-quality evidence that supports topical CBD as an effective treatment for joint pain. Not only is this a function of the simple fact that we have really just begun to investigate CBD in-depth, but its legal status can also make it difficult for large-scale university studies to commence.
Nevertheless, studies of topical CBD in animals suggest it may be beneficial for neuropathic pain and osteoarthritis.
It’s important to note that these experiments involve animal models of disease and do not always translate to the same or similar effects in humans. Therefore, these types of studies need to be evaluated with a small measure of discernment.
Neuropathic pain occurs when nerves inappropriately send pain signals to the brain. Neuropathic pain can be the result of nerve damage, diabetes, trauma or physical injury, and even some medications.
Neuropathic pain is often described as a shooting and burning sensation like pins and needles.
Arthritis is the medical term for joint inflammation. There are many different types of arthritis, but osteoarthritis is the most common form. Osteoarthritis occurs when the cartilage between bones breaks down over time due to wear and tear.
Symptoms of osteoarthritis include joint swelling, stiffness, and decreased range of motion.
Symptoms are usually localized to one or two weight-bearing joints such as the knees or hips and cause pain in the affected joint(s). Inflammation and neuropathic pain often co-occur with osteoarthritis and can worsen joint pain.
Very few studies using topical CBD for joint pain have been carried out to date. CBD has poor absorption when taken orally, so using topical CBD may more effectively deliver CBD to painful joints.
Animal studies suggest that transdermal delivery of CBD results in better absorption than CBD taken orally.
“The transdermal administration of CBD has also been observed to provide better absorption than the oral administration route…”
Topical and transdermal dosage forms are both applied to the skin, but topical dosage forms affect the site of application whereas transdermal dosage forms are intended to be absorbed and have a more widespread effect.
Topical CBD products often contain other potentially active ingredients such as camphor, menthol, essential oils, and other aromatic compounds. Due to the multiple potentially active ingredients in these products, it’s hard to determine if an effect is due to CBD, or other ingredients present in the product.
CBD has a variety of effects, but we will focus here on its mechanism behind a potential reduction in joint pain due to neuropathic pain.
CBD binds and activates a receptor on our nerve endings called the transient receptor potential vanilloid-1 (TRPV1).
TRPV1 receptors are expressed on nerve fibers in our skin and are involved in pain perception. Qutenza (capsaicin) is a transdermal patch that’s approved by the FDA for the treatment of neuropathic pain.
Capsaicin works by activating TRPV1 receptors, which might initially increase pain, but then decreases the amount of TRPV1 receptors on nerve endings resulting in a reduction of pain.
This mechanism of CBD holds the most weight in my opinion because it’s been verified to work in clinical trials by the FDA and because the evidence supporting CBD’s affinity to bind and activate the TRPV1 receptor is well documented:
“(CBD) behaved as a full agonist as compared to capsaicin…The efficacy was almost identical to that of a maximal concentration of capsaicin.”
In theory, topical CBD may activate TRPV1 receptors in the skin and reduce joint pain similar to how capsaicin works, but more evidence is needed to confirm this mediates pain relief in humans.
In addition to binding TRPV1 receptors, CBD may work to reduce pain in other ways. Topical CBD reduced two markers of inflammation in an animal model of osteoarthritis.
“Topical treatment with CBD reduced leukocyte trafficking and joint hyperemia…”
A reduction of leukocyte (white blood cell) trafficking and hyperemia (excess blood volume) may have contributed to pain relief observed in the same study:
“…local CBD administration inhibited pain and peripheral sensitization in established OA (Osteoarthritis).”
CBD is also known to have neuroprotective effects. This means it preserves the structure and function of nerves.
Again, the same study mentioned above showed that CBD used before osteoarthritis prevented a form of nerve damage called demyelination.
“Prophylactic CBD reduces joint nerve demyelination in MIA-induced OA”
While studies in humans are limited, some animal studies show that topical CBD may be effective for joint pain due to osteoarthritis and neuropathic pain.
Although preliminary animal studies have shown promise, more large, well-designed studies in humans are necessary.
As discussed, there is no high-quality evidence supporting topical CBD’s effectiveness for joint pain in humans.
Topical CBD products tend to use multiple, potentially active, ingredients, so determining if an effect is due to CBD alone is difficult.
Animal studies suggest that topical CBD may reduce joint pain due to osteoarthritis and Neuropathic pain by activating TRPV1 receptors and through less established anti-inflammatory and neuroprotective pathways. More studies are needed to further understand these mechanisms and to establish topical CBD’s effectiveness in humans.
As with any drug or natural product, you should talk with your doctor before using topical CBD.