A new study released earlier this month on May 2 in the research journal Pain suggests that an injection of cannabis terpenes is “roughly equal” to the number of pain reduction markers from an injection of morphine.
“Terpenes from Cannabis sativa induce antinociception in a mouse model of chronic neuropathic pain via activation of adenosine A2A receptors” features researchers hailing from multiple departments at the University of Arizona as well as with awarded funding from the National Institutes of Health.
Researchers sought out to see how cannabis can potentially treat chronic pain. “A question that we’ve been very interested in is could terpenes be used to manage chronic pain?” said John Streicher, PhD, who is the lead author of the study. “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.”
While both CBD and THC have been found to be beneficial in treating chronic pain, researchers explained that the effects are moderate, and “can come with unwanted psychoactive side effects.” Terpenes are a path around the use of psychoactive substances, which “offer an alternative path to pain relief without adverse side effects.”
For the purpose of this study, researchers examined five different terpenes: alpha-humulene, beta-caryophyllene, beta-pinene, geraniol, and linalool. Researchers utilized a mouse model focused on neuropathic pain, which is a well-known condition that stems from nerve damage caused by chemotherapy medications.
Each terpene was tested on its own and the results were compared with morphine as well. All five terpenes showed significant pain reduction “near to or above the peak effect of morphine” individually, and even more powerful effects on pain when combined. “That was really striking to us, but just because something relieves pain doesn’t necessarily mean it’s going to be a good therapy,” Streicher said.
The negative effects of using opioids include an activation of the reward system in the brain, which can lead to an increased tolerance to the effects over time, and addiction as well. But terpenes don’t lead to these same effects. “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?” said Streicher. “What we found was yes, terpenes do relieve pain, and they also have a pretty good side effect profile.”
Researchers also examined the method of consumption with terpenes, including injection, oral dosing, and inhalation. When orally administered or inhaled, the effects were “significantly reduced or absent.” “A lot of people vape or smoke terpenes as part of cannabis extracts that are available commercially in states where cannabis use is legal,” said Streicher. “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. Part of the confounding factor is that terpenes smell quite nice and it’s hard to disguise that aroma, so people could be kind of having the psychosomatic placebo-style effect.”
Previously, Streicher and his team published their findings from a similar study back in July 2021. At the time, their results showed promising evidence regarding terpenes being used for pain relief, especially when studying the benefits of the entourage effect. Although their hypothesis was to examine how cannabinoids affected pain, they were ultimately surprised by how powerful the entourage effect actually was. “It was unexpected, in a way,” Streicher said in 2021. “It was our initial hypothesis, but we didn’t necessarily expect terpenes, these simple compounds that are found in multiple plants, to produce cannabinoid-like effects.”
Looking toward the future, Streicher plans to utilize these results in his next research endeavor. In a press release, he explained that his next hypothesis will explore if terpenes can block the body’s reward system and also still provide the same pain treatment as seen in the most recent results. “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. That’s what we are looking at now,” said Streicher.
Over time, other terpene studies have revealed how they can serve as a treatment option for certain conditions.
A study from 2020 published in Molecules defined terpenes in detail to “describe sources of cannabis terpenes and to explain the biosynthesis and diversity of terpene profiles in different cannabis chemovars.” Their results showed that terpenes and cannabinoids used together show evidence of the entourage effect.
In February 2023, one study from researchers at the University of New Mexico found that patient relief was best experienced with higher terpene levels.
In October 2023, a study performed by researchers at Abstrax Tech and published in the American Chemical Society’s journal, Omega, showed that the importance of terpenes is “overstated” when it comes to defining the differences between cultivars. “This discrepancy suggests that while these classifications may be helpful for chemotaxonomic purposes, they lack the chemical information necessary to differentiate these varieties from an aroma perspective,” the study stated.