A newly published decade-long study is reporting unusually large reductions in opioid use among patients receiving medical cannabis for severe chronic low back pain. Researchers followed 1,000 cannabis-naïve patients enrolled at a specialized orthopedic pain clinic and found that, among the 638 people who completed the full ten years of follow-up, average opioid consumption fell from 62.8 morphine milligram equivalents per day to 6.4 milligrams—a reduction of 89.8 percent. More than 91 percent of long-term participants reduced their opioid dose by at least half, while pain scores and measures of physical disability also improved substantially. The study was published September 14, 2026, in the European Spine Journal.
The results are remarkable, but the researchers themselves urge caution. This was a single-center observational study without a placebo or untreated control group, meaning it cannot establish that cannabis alone caused the reductions. Nearly 36 percent of the original cohort did not complete the full decade, and patients who continued for ten years may disproportionately represent people who responded well to treatment. The investigators explicitly acknowledge that their improvements were far larger than those seen in randomized cannabis trials and say survivorship bias, placebo and expectancy effects, regression to the mean and changes in other treatments likely contributed to the magnitude of the results. They describe the findings as hypothesis-generating rather than practice-changing.
Researchers Followed 1,000 Cannabis-Naïve Back Pain Patients for a Decade
The study was conducted by researchers affiliated with Rabin Medical Center, Tel Aviv University and Clalit Health Services in Israel. Investigators analyzed a prospective registry established in 2015 at a specialized orthopedic pain clinic. The cohort consisted of 1,000 consecutive adults with chronic low back pain who had never previously used cannabis, confirmed through patient history and urine testing. All participants had structural spinal abnormalities confirmed by CT or MRI and had experienced inadequate results from conventional approaches including physical therapy, anti-inflammatory medication and opioid therapy. Patients also had to have been taking opioids continuously for at least one year before enrollment.
The population was dealing with longstanding disease rather than temporary back discomfort. Average pain duration was approximately 9.8 years, and imaging showed conditions including spinal stenosis in 48.6 percent, disc degeneration in 26.9 percent and vertebrogenic low back pain in 22.9 percent; 42 percent had more than one structural diagnosis. Mean age was 48.9 years, and 64 percent were men. Baseline pain averaged 8.64 on a ten-point scale, while patients’ average Oswestry Disability Index score exceeded 52 percent, indicating substantial functional impairment.
Patients received physician-supervised medical cannabis from licensed producers. Treatment included vaporized dried flower and oral or sublingual cannabis oils, generally introduced according to a “start low, go slow” approach. THC-dominant preparations typically began around 2.5 to 5 milligrams of THC before gradual titration. Importantly, investigators did not force patients through a standardized opioid taper. Decisions to reduce opioids or other medications were made individually by patients and their physicians according to symptoms and clinical response.
Opioid Use Fell 89.8 Percent Among 10-Year Completers
The study’s primary endpoint was opioid consumption measured in morphine milligram equivalents, or MME. Among the 638 patients who completed all ten annual assessments, average opioid consumption declined from 62.8 MME per day at baseline to just 6.4 MME at year ten. That represented an absolute reduction of 56.4 MME and a relative decline of 89.8 percent. Researchers had defined a reduction of at least 50 percent as clinically meaningful; 582 of the 638 completers, or 91.2 percent, reached that threshold.
Interestingly, most of the opioid decline appeared early. Mean opioid consumption dropped to only 3.1 MME per day by the end of the first year, representing a 94.8 percent reduction from the completers’ original level, and remained comparatively low throughout subsequent follow-up. Despite the dramatic decline in average dose, complete opioid cessation was less common: 42 patients, or 6.6 percent of completers, were taking no opioids at year ten. This distinction is important because the headline finding reflects dose reduction across the group, not that nine out of ten patients stopped opioids entirely.
The scale of the decrease greatly exceeds what previous reviews have found. A 2021 BMJ Open systematic review examined five randomized trials and 12 observational studies of cannabis added to opioid therapy. The observational evidence suggested an average reduction of about 22.5 MME per day, but investigators rated the certainty of that evidence as very low because of methodological limitations. Randomized trials could not adequately determine opioid-sparing effects because participants were generally instructed not to change their opioid doses.
Pain Scores Fell From 8.7 to 1.4
Opioids were not the only measurement to change. Among ten-year completers, average pain intensity fell from 8.71 to 1.37 on a zero-to-ten numerical rating scale, an 84.2 percent reduction. Researchers considered a decline of at least 30 percent clinically meaningful; 96.6 percent of completers crossed that threshold, while 89.2 percent reported pain scores of three or lower at year ten.
That improvement is exceptionally large by chronic pain research standards—and it is also one of the main reasons the authors caution against interpreting the study as proof of cannabis efficacy. A major randomized, placebo-controlled phase 3 trial published in Nature Medicine in 2025 tested a standardized full-spectrum cannabis extract in 820 adults with chronic low back pain. Cannabis produced a statistically significant improvement over placebo, but the difference was only about 0.6 points on the pain scale. Approximately 54.1 percent of cannabis-treated participants achieved at least 30 percent pain reduction compared with 39.5 percent receiving placebo.
By comparison, the observational study’s 96.6-percent responder rate is dramatically larger. The authors themselves highlight this discrepancy and argue that it probably cannot be explained by pharmacology alone. Long-term self-selection, patient expectations, additional treatments, natural fluctuations in chronic pain and the fact that successful patients may have been more likely to remain in the program could all inflate the apparent benefit.
Physical Disability Improved More Slowly Than Pain
Functional recovery followed a different timeline. Researchers assessed disability with the Oswestry Disability Index, a standard measure evaluating how back pain affects activities such as walking, sitting, standing, sleeping and personal care. Scores range from zero to 100 percent, with higher values indicating greater disability. Among long-term completers, the average score declined from 52.9 percent to 36.8 percent, an absolute improvement of 16.1 points and relative reduction of 30.4 percent. Approximately 62.1 percent of completers achieved the researchers’ predefined clinically meaningful improvement of at least ten points.
Unlike pain and opioid consumption, however, functional improvement developed gradually. The average disability score remained around 50.5 percent through year five and was still 47.2 percent at year seven before falling more sharply by year ten. Investigators suggest that reduced pain may occur well before patients regain strength, mobility, conditioning and confidence after years of chronic disability. Psychological factors such as fear of movement, depression and pain-related avoidance can also persist after pain itself improves.
This lag is clinically significant because pain relief and restored function are not interchangeable. A therapy can make pain feel less intense without immediately reversing years of muscle deconditioning or structural spine disease. The finding therefore provides a more nuanced picture than the striking opioid statistics alone: even after major reductions in reported pain, many patients continued to experience meaningful physical limitations.
Use of Several Other Prescription Drugs Also Declined
One of the more unexpected findings was the reduction in medications beyond conventional opioids. At baseline, 89.7 percent of patients used tramadol or tapentadol, 78.8 percent used benzodiazepines, 77.7 percent used selective serotonin reuptake inhibitors and 31.3 percent used gabapentinoids. By year ten among completers, those percentages had fallen to 5.6 percent, 5.3 percent, 5.8 percent and 0.6 percent, respectively. Most of the reductions occurred during the first two years.
These changes were not dictated by the study protocol. Medication reductions were made through ordinary physician-patient decisions, making it impossible to determine whether cannabis directly replaced each drug. Patients may have reduced benzodiazepines because sleep or anxiety improved, for example, while antidepressants could have been discontinued for entirely separate reasons. Still, the broad decline suggests that long-term medical cannabis treatment was occurring within a much larger reduction in medication burden rather than simply replacing one opioid with another analgesic.
Earlier observational research has reported similar patterns. A 2020 study of 61 opioid-treated patients with chronic back pain found that about half eventually stopped prescription opioids after receiving medical cannabis recommendations, although the median time to discontinuation was more than six years. As with the new study, however, the lack of randomized controls prevents firm conclusions about causation.
Cannabis Doses Did Not Continuously Escalate Over Ten Years
Long-term tolerance is an obvious concern when evaluating any analgesic. In this cohort, average cannabis consumption increased during initial titration but stabilized by approximately year two. Among completers, mean use reached roughly 38.7 grams per month in year two and 47.5 grams per month by year ten, with an average of approximately 40.9 grams per month across the study. Researchers calculated an approximate THC-to-CBD ratio of 3.8:1. About 62 percent primarily used vaporized cannabis flower, 31 percent used oral oils and 7 percent used a combination.
The authors interpret the lack of continuous dose escalation as evidence against substantial pharmacological tolerance, but this conclusion should also be treated cautiously. Cannabis dosing measured in grams does not perfectly capture cannabinoid exposure, and products may differ in THC and CBD concentration. Furthermore, the cohort consisted of medically supervised patients using regulated products, so results should not automatically be extrapolated to unsupervised high-potency recreational cannabis use.
Reported Serious Adverse Events Were Rare
Across 8,089 patient visits, investigators recorded tolerability-related adverse events during 11.4 percent of visits. Dry mouth was most common, followed by gastrointestinal symptoms and eye irritation. Cognitive symptoms, palpitations, dizziness and hypotension were reported less frequently. Two visits involved serious psychiatric events, corresponding to 0.02 percent of recorded visits. Researchers reported no cannabis-related hospitalizations, deaths or treatment discontinuations and identified no clinical cases of cannabis use disorder.
Those results appear reassuring but should not be interpreted as establishing long-term cannabis safety. Patients with severe psychiatric illness or substance-use disorders other than prescription opioid use were excluded from enrollment, creating a population already at lower risk for some complications. The researchers also acknowledged that they did not systematically evaluate cannabis use disorder with a validated diagnostic instrument.
The distinction becomes particularly important when comparing controlled medical use with high-potency cannabis in the general population. The study involved physician-supervised titration and licensed products, conditions considerably different from unrestricted consumption.
The 36 Percent Dropout Rate Is a Major Limitation
Of the original 1,000 patients, 638 completed the full decade, meaning 362 participants were no longer providing complete ten-year data. Investigators report that departures were attributed primarily to patient preference, relocation, loss to follow-up and several deaths unrelated to treatment. Baseline characteristics of completers and non-completers were reportedly similar, and statistical sensitivity analyses incorporating all available observations produced endpoint estimates broadly consistent with the completer analysis.
Nevertheless, attrition remains one of the study’s largest weaknesses. People who continue a treatment for ten years are inherently more likely to be people who believe it is helping them. The authors explicitly acknowledge the possibility that the remaining cohort became enriched with unusually strong responders—what they call potential “super-responders.” Neither mixed-effects modeling nor carrying patients’ last measurements forward can fully remove that kind of bias.
The single-center design adds another limitation. Patients came from a specialized orthopedic pain clinic and had confirmed spinal abnormalities, severe pain, longstanding opioid exposure and failure of conventional treatments. Results therefore cannot automatically be generalized to people with mild or nonspecific back pain.
What the Study Adds to the Medical Cannabis Evidence
The research is still important precisely because randomized clinical trials rarely follow chronic-pain patients for a decade. The 2025 Nature Medicine randomized trial provides much stronger evidence that a standardized cannabis extract can produce a modest benefit for chronic low back pain compared with placebo. The new European Spine Journal study addresses a different question: what happened over ten years among severely affected patients who remained in a supervised medical cannabis program?
Its answer is striking. Among long-term completers, opioid use was almost 90 percent lower, pain scores dropped dramatically, disability improved and use of several other prescription medications declined. Yet the effect sizes were several times larger than those observed in controlled trials, making caution essential. The authors themselves state that the findings require confirmation through longer-term randomized or pragmatic controlled studies.
For now, the most defensible conclusion is not that medical cannabis has been proven to eliminate the need for opioids in chronic back pain. It is that one of the longest medical cannabis studies conducted in this population found a sustained association between supervised cannabis treatment and dramatically lower opioid exposure over ten years. Combined with emerging randomized evidence showing more modest but genuine analgesic effects, the results strengthen the case for rigorous trials specifically designed to determine whether cannabis can safely help selected chronic-pain patients reduce long-term opioid therapy—and by how much.
