CBD (cannabidiol) products are all the rage right now, with countless companies and merchandisers offering a wide variety of options. While edibles are usually the products of choice, some prefer topical CBD products to avoid gastrointestinal problems or to reap potential pain reduction effects from local application to specific body parts, such as a sore shoulder or ankle. It is, however, extremely probable that there are significant differences in outcomes between oral and topical administration of CBD products. 

What’s CBD and what is it good for?

CBD is one of the many compounds found in Cannabaceae plants, or, as most people call them, cannabis plants. It can be extracted from both the marijuana and hemp plants; however, most US states require that CBD oil products come from hemp and do not contain more than 0.03% THC. CBD oil does not produce a high, but it does interact with brain chemistry, so saying it is completely non-psychoactive would be inaccurate. 

The effects of CBD on the body can be pinned to the body’s endocannabinoid system, which regulates numerous processes such as appetite, pain, and mood. The body produces its own cannabinoids, but introducing CBD into the body amplifies the endocannabinoid system. 

There is evidence that CBD may be effective in treating some very dangerous childhood epilepsy syndromes, including Lennox-Gastaut syndrome (LGS) and Dravet syndrome. CBD seems able to reduce the number of seizures or stop their incidence altogether, even in some patients who don’t respond to typical antiseizure medication. In 2018, the FDA approved the first ever cannabis-derived, medically certified drug for these conditions, Epidiolex, which is formulated with CBD. 

Regarding its health benefits, there is evidence to suggests CBD can relieve pain and anxiety. In 2017, researchers at the National Center for PTSD-Dissemination & Training Division in Palo Alto, California, concluded that some CBD products may help patients sleep better. 

“Cannabidiol (CBD) may have therapeutic potential for the treatment of insomnia,” researchers wrote in their study. “THC may decrease sleep latency but could impair sleep quality long-term,” they said. 

Edibles vs topicals 

CBD is hydrophobic, meaning it repels water molecules and therefore cannot be water-soluble—not on its own at least. It is also lipophilic, meaning it is attracted to oils and fats. For this reason, CBD applied on the skin tends to stay on the outer layers and doesn’t cross into the bloodstream.

Few studies focus on CBD alone for managing pain, and all are on animals. Most studies to find pain relief properties involve the whole cannabis plant, and contain THC and CBD, along with dozens of other cannabidiols. A 2017 study published in the journal Pain, gave rats a dose of CBD or saline directly into their knee joints through an intra-arterial injection, after previously injecting them with a substance that caused osteoarthritis. According to the results, the rats that received a high dose of CBD exhibited less inflammation in the joint area and a reduction in pain-related behavior, such as shaking or withdrawing the affected paw, when compared to controls that received the saline solution. 

Another similar study, which was published in the European Journal of Pain, also investigated arthritis in rats, but this time using a topical formulation of CBD instead of an injection. The rats received either a 10% CBD formulation or a 1% CBD compound for four consecutive days. The rats that received the highest dose of topical CBD showed significantly lower levels of inflammation and lower pain-related behaviors. 

However, while those results are encouraging, rat studies don’t always translate to humans, so such findings should be taken with a grain of salt. For instance, although many people anecdotally claim that topical CBD products help them manage their pain after a workout or injury, they might be experiencing reduced anxiety, which is known to interfere with how we manage pain. CBD topical products could also act like placebos. There is really no way to tell unless clinical trials are performed on humans, which are expensive and ethically challenging. 

Zynerba Pharmaceuticals performed the only phase two clinical trial that we know of, using a CBD transdermal gel that the company developed in-house. The study involved 320 patients with knee osteoarthritis who received either 250 mg of ZYN002 4.2% CBD gel daily, 500 mg of ZYN002 daily, or a placebo, over 12 weeks. Although the study found some evidence of a reduction in pain and improvements in physical function, scores for measures of pain were not statistically different from placebos. 

While the effects of edibles and topical CBD on animals looks positive and are good to read, more scientific research is needed before definitive conclusions can be reached about its effects on humans. 

Is topical CBD safe? 

The bottom line is that there is insufficient evidence demonstrating that topical CBD products are effective for managing pain, which is the main reason people buy them. We simply cannot come to definite conclusions until more clinical trials are performed. But are there any downsides to using CBD? CBD oil taken orally is known to cause side effects such as nausea, fatigue and irritability. CBD may also interact with blood thinner medication. 

The main problem with CBD right now, however, is that oftentimes customers do not buy products for their advertised uses. CBD is primarily marketed and sold as a supplement, not a medication. By US law, the FDA does not regulate the safety and purity of dietary supplements. If you do decide to purchase topical CBD products, only buy from vendors that can supply a certificate of analysis that attests that the products contain the correct amount of CBD, as advertised.