According to the American Academy of Pain, nearly 50 million Americans suffer from persistent pain. Unfortunately, it is estimated that four out of every ten people living with moderate-to-severe pain have yet to experience relief. After reviewing a series of trials in 1997, the U.S. Society for Neuroscience concluded that “substances similar to or derived from marijuana could benefit the more than 97 million Americans who experience some form of pain each year93.” Although a wide variety of prescription analgesic drugs ranging from aspirin to oxycontin are available to treat pain, none of these drugs are completely adequate for all patients and many cause severe side-effects with continued use. Opiate painkillers are notorious for causing severe nausea, constipation, disorientation, and drowsiness. Prolonged use of opiates can increase tolerance and, in some cases, result in dependence or addiction. Even milder, over the counter analgesics can pose serious toxic risks. Drugs such as aspirin can cause
stomach irritation and in some cases ulceration. Prolonged use of acetaminophen can result in liver damage. Ibuprofen use can cause kidney failure and vascular damage. Each of these analgesics can produce fatal overdose, unlike cannabis.

The safety record of cannabis is remarkable, and its centuries of use as an analgesic well documented94,95. In their meta-analysis of the available data as of the late 1990s, the Institute of Medicine acknowledged the wide use of cannabis for pain, noting that “after nausea and vomiting, chronic pain was the condition cited most often to the IOM study team as a medicinal use for marijuana10.” Currently, pain is by far the most common condition for which physicians recommend the use of cannabis.

Many well-designed, double-blind placebo-controlled clinical trials clearly demonstrate that cannabis can reduce pain of many types, not just hard-to-treat neuropathic pain. A review of the body of scientific research concerning the analgesic effects of cannabis concluded that there is now unequivocal evidence that cannabinoids are anti-nociceptive (capable of blocking the transmission of pain) in animal models of acute pain96-100.” Human and animal studies have demonstrated that cannabinoids also work well in combination with opiate painkillers. One animal study found that the pain-relieving dose of morphine was lowered with the addition of a small dose of THC. Codeine’s efficiency was also significantly enhanced97. Research suggests that direct and indirect interactions between opioid and cannabinoid receptors not only enhance analgesia but also reduce the development of tolerance to opiates in mammals. These interactions hold promise for developing therapeutic strategies that provide better pain relief with a lower doses of opiates, resulting in fewer of the dangerous and debilitating side effects that patients reliant on opiate pain killers experience100,101.

Decades of research on cannabis' effectiveness in pain management include clinical human trials and volumes of anecdotal evidence, as well as new understanding of how activation of the cannabinoid system in the central nervous system reduces sensitivity to pain76,102-107. Some of the most encouraging clinical data on the effects of cannabinoids on pain involve the treatment of intractable cancer pain and hard-to-treat neuropathic pain. Somewhere between 25% and 45% of cancer patients experience neuropathic pain. As mentioned in the discussion of treating HIV, the effectiveness of cannabis and cannabinoids in relieving neuropathic pain has been demonstrated in dozens of preclinical and clinical trials. Reviews of the literature often note that a large number of research articles have demonstrated the efficacy of cannabinoids for treating neuropathic pain and conclude that cannabinoids show promise as a treatment1,76,108-110. Multiple clinical trials have shown that a dosage-controlled whole-plant extract of cannabis (Sativex) relieves intractable cancer pain, and does so better than THC alone. A recent double blind, randomized, placebo-controlled trial of 360 cancer patients in 14 countries found that pain scores improved significantly with a cannabis extract. Researchers report that the combination of natural cannabinoids in Sativex “is an efficacious adjunctive treatment for cancer-related pain” for patients who do not get adequate relief from opiate painkillers such as Oxycontin or Vicodin111,112.

Pain from spinal injuries may also be treatable with cannabis. Several sets of researchers have recently published findings on the efficacy of cannabinoids in treating pain resulting from spinal cord injuries (SCI). A French team, noting that “very few pharmacological studies have dealt specifically with neuropathic pain related to SCI,” suggests that for “refractory central pain, cannabinoids may be proposed on the basis of positive results in other central pain conditions (e.g. multiple sclerosis).” Researchers have demonstrated in an animal model of SCI pain that cannabinoids yield more consistent positive results than conventional analgesics such as opiates, which “decrease in efficacy with repeated treatment over time,” concluding that drugs targeting the body's cannabinoid receptors  “hold promise for long-term use in alleviating chronic SCI pain113.”
Researchers have also determined that neuropathic pain may be treatable via bolstering the body's natural cannabinoids, the endocannabinoids. A study that inhibited the two enzymes that break down the body's natural cannabinoids found that preserving them “reduces neuropathic pain through distinct receptor mechanisms of action” that “present viable targets” for developing new analgesic drugs114. Drugs which can selective target CB2 cannabinoid receptors, which are almost completely absent from the central nervous system, have also been shown to have therapeutic potential for both inflammatory and neuropathic pain control115.


Abrams, D. I., Couey, P., Shade, S. B., Kelly, M. E. & Benowitz, N. L. Cannabinoid–Opioid Interaction in Chronic Pain. Clin Pharmacol Ther 90, 844–851 (2011).