By Pat Anson, PNN Editor

What gives the cannabis sativa plant it’s pain-relieving properties?

Most people will tell you it’s cannabidiol (CBD) and/or tetrahydrocannabinol (THC), the two most well-known chemical compounds found in cannabis.  

But researchers at University of Arizona Health Sciences say terpenes -- aromatic compounds that give cannabis its distinctive “skunky” smell – have analgesic effects as well. In fact, in a new study published in the journal PAIN, they report that cannabis terpenes are just as effective as morphine in reducing neuropathic pain in laboratory animals.

“A question that we’ve been very interested in is could terpenes be used to manage chronic pain?” lead researcher John Streicher, PhD, a Pharmacology Professor at UA’s College of Medicine in Tucson, said in a press release. “What we found is that terpenes are really good at relieving a specific type of chronic pain with side effects that are low and manageable.”

Terpenes are found in all plants and are the main component of essential oils. Terpenes give lavender, sage and eucalyptus oils their distinctive smells, which are used to promote relaxation or even reduce pain and inflammation. In nature, terpenes help plants attract pollinators such as bees or to protect themselves from predators.

Most plants have only two dominant terpenes, but cannabis has up to 150 terpenes. Streicher and his colleagues tested five of the cannabis terpenes by injecting them into mice with chemotherapy-induced neuropathic pain.

They found that each of the five terpenes reduced nerve pain significantly, at levels similar to or even better than morphine. And when combined with morphine, the analgesic effects were enhanced even further.

Perhaps the most striking discovery is that the mice showed no signs of euphoria or “liking” terpenes – a sign that they may not have abuse potential.

“We looked at other aspects of the terpenes, such as: Does this cause reward? Is this going to be addictive? Is it going to make you feel awful?” Streicher said. “What we found was yes, terpenes do relieve pain, and they also have a pretty good side effect profile.”

In addition to injections, researchers also administered terpenes to the mice orally and through inhalation from a vaporizer. The results were the same. The mice had significant pain relief with no side effects or signs of addiction.

More research is needed, but some cannabis companies are already incorporating terpenes into their products. Lemon Kush, for example, is a marijuana strain that contains limonene, a terpene that smells like lemon, while the hybrid Blue Dream has a terpene that’s also found in blueberries.

“A lot of people vape or smoke terpenes as part of cannabis extracts that are available commercially in states where cannabis use is legal,” Streicher said “We were surprised to find that the inhalation route didn’t have an impact in this study, because there are a lot of at least anecdotal reports saying that you can get the effects of terpenes whether taken orally or inhaled.”

The next step for Streicher and his research team is to study whether terpenes can block the abuse potential of opioids, while at the same time enhancing their analgesic effects.

“This brings up the idea that you could have a combination therapy, an opioid with a high level of terpene, that could actually make the pain relief better while blocking the addiction potential of opioids,” Streicher said.