Chronic pain is a pervasive issue affecting an estimated 20% of the human population, according to the Journal of Pain Research. Traditionally, opioids have been the go-to pharmacological therapy for managing chronic pain. However, the opioid epidemic, fueled by dependence and overdose risks, has prompted a search for safer alternatives. Cannabis is emerging as a promising option, but a critical question remains: does long-term cannabis use increase sensitivity to pain in the same way that opioids do?

Understanding Hyperalgesia and Opioids

One lesser-known but significant issue with long-term opioid use is opioid-induced hyperalgesia. This condition results in increased sensitivity to pain, necessitating higher doses to achieve the same pain relief. As patients' tolerance to opioids grows, so does their sensitivity to pain, creating a vicious cycle that elevates the risk of addiction and overdose. Given that both cannabinoids and opioids interact with the nervous system in similar ways to reduce pain, it’s essential to explore whether cannabis carries the same risk of hyperalgesia.

Cannabis and Pain Sensitivity: The Research Question

A recent study led by Michelle St. Pierre, a doctoral student at the University of British Columbia (UBC), sought to answer this very question. Published in April 2020, the study compared regular cannabis users with non-users to determine any differences in pain sensitivity. The researchers hypothesized that, like opioids, cannabis might increase pain sensitivity following acute use.

Conducting the Study

The study involved 83 adult students from UBC, divided into two groups: regular cannabis users (more than three times per week) and non-users (either never used cannabis or hadn’t used within the last month). Importantly, the cannabis users were recreational rather than medical users. Pain sensitivity was assessed using the cold-pressor task, a common method in clinical trials for evaluating pain tolerance and sensitivity.

In the cold-pressor test, participants submerge one hand in ice water for up to two minutes. Pain builds until the individual withdraws their hand. Researchers measured pain sensitivity by recording the time until participants first reported pain and pain tolerance by the total time they kept their hand submerged. The results were assessed using a Visual Analogue Scale, a validated measure for acute and chronic pain.

Findings: Cannabis and Hyperalgesia

The study found no difference in pain sensitivity and tolerance between regular cannabis users and non-users. This result stands in stark contrast to opioid therapy, suggesting that cannabis may not carry the same risk of hyperalgesia as opioids. According to co-author Zach Walsh, this finding is particularly encouraging for patients using cannabis to manage pain, as increased pain sensitivity with opioids can complicate treatment.

Considerations and Limitations

While these findings are promising, several limitations must be noted. The study relied on self-reported cannabis use, and researchers did not confirm cannabinoid metabolites, potentially leading to misclassification of participants. Additionally, the duration of cannabis use prior to the test was not recorded, which might influence pain reactivity. The cold-pressor task, while useful, may not fully replicate real-life pain experiences, and the study’s participants were healthy young adults, limiting generalizability to the broader population, including those using cannabis for chronic pain.

Looking Forward: The Need for Further Research

In their conclusion, the researchers called for ecological momentary assessment (EMA) studies to better understand how cannabis interacts with pain in real-life scenarios. EMA studies allow participants to report symptoms, moods, and behaviors close to the time of the experience, offering a more detailed and accurate measurement than other research methods.

The question of whether cannabis increases sensitivity to pain like opioids is critical in shaping pain management strategies. While current evidence suggests that cannabis does not cause hyperalgesia, the complexities of cannabis interactions with the human body warrant further research. As we continue to explore cannabis as a safer alternative to opioids, it’s essential to stay informed and cautious, ensuring that we maximize benefits while minimizing risks. For now, the findings offer a hopeful outlook for those seeking effective pain relief without the pitfalls of increased pain sensitivity.