Cannabis as an analgesic to opioids

by Dr. Adie Wilson-Poe

Humans have used cannabis for health purposes for thousands of years. Starting around the year 2900 BCE, the Chinese pharmacopoeia included cannabis; the ancient Egyptians, the Greeks, and Romans followed suit. Cannabis was even a mainstream medicine in the United States throughout the 1800s.

All of these cultures shared a common use for cannabis: pain relief.

For today’s pain doctors and scientists, this comes as no surprise at all. Cannabinoids — the unique molecules found within the cannabis plant — have been extremely well-studied for their pain-relieving properties¹⁴. In short: Cannabinoid receptors are widely expressed throughout the brain’s pain processing regions, and when cannabinoids are administered directly to these brain areas (in animals), they produce profound pain relief¹¹.

Opioid receptors are expressed in these exact same brain regions, too. In fact, they’re found in the same brain cells (neurons) that express CB1 cannabinoid receptors, and it turns out the mechanisms of opioid and cannabinoid pain relief are staggeringly similar. That’s because both cannabinoid and opioid receptors belong to the same family of proteins — so both cannabis and opioid-based medications initiate nearly identical processes after binding to the receptors.

In other words, cannabis and opioid treatments spark similar reactions within our brains to relieve us of pain. However, the way cannabis does it is different in a few very important ways.

One molecule vs. hundreds

Prescription opioids generally consist of just one molecule. Cannabis, however, contains hundreds of distinct, biologically active molecules. Although tetrahydrocannabinol (THC) is very good at directly binding to CB1 receptors in the brain’s pain headquarters, it doesn’t act alone. Many of the molecules in cannabis have anti-inflammatory properties¹⁸, and inflammation is a huge part of the experience of pain.

To be clear, opioids are the best weapon we have against acute, severe pain. But long-term exposure to opioid-based drugs can have dire (even fatal) consequences, so despite cannabis’ relative “weakness” in relieving bodily pain in comparison, people with chronic pain overwhelmingly prefer it¹⁵.

The bodily sensation of pain may not completely disappear like it does with opioids, but because cannabis dramatically improves perceived control over pain, it also improves the ability to function in daily life⁶.

The most prominent reason for a patient’s preference for cannabis is the relative lack of side effects. Opioids are fundamentally dangerous drugs — it’s relatively easy to follow the doctor’s orders and still overdose. And even when used as directed, opioids can cause cognitive impairment, sleepiness, gastrointestinal distress, slowed wound healing, nausea, and itching.

In contrast, the side effects of cannabis are generally mild and well-tolerated, and fatal overdose is virtually impossible.

Cannabis shouldn’t be the alternative — it should be the initial treatment

So if cannabis is less addictive, non-lethal, has fewer undesirable side effects and can be safely taken over the long term, then why is it our last resort instead of a first-line tool for treating pain?

The answer to this questions is, unfortunately, a largely political and economic one. However, some recent developments may flip the script.

In 2016, the Centers for Disease Control and Prevention (CDC) released a new set of opioid guidelines as an attempt to manage the opioid crisis from its source: the doctor’s prescription pad. Among those recommendations was that non-opioid pain relievers should be used to treat most cases of chronic pain. On the heels of these recommendations, the National Academies of Science and Medicine conducted an exhaustive review of more than 10,000 studies on humans, concluding that cannabis is indeed safe and effective for the management of chronic pain.

So only one domino remains standing: Cannabis remains a Schedule I Controlled Substance at the federal level. Should cannabis be rescheduled, doctors will finally be able to counsel their patients on safe and effective cannabis use — so they’ll be able to openly discuss, prescribe, and receive continuing education about cannabis medicine. What’s more, they’ll finally be able to uphold their Hippocratic oaths to do no harm without also risking their careers and livelihoods.

There’s no doubt in my mind that like so many cultures before ours, we will welcome cannabis back into our standard of care for pain management.