Background and aims: Although the use of Herbal Cannabis (HC) for chronic pain is rising, scientific evidence for its associations with reduction in analgesics reduction is scarce. The aim of this study is to present the changes from baseline in analgesics consumption during one year of HC treatment. 
Methods: Patients with chronic pain for whom an application for using HC was completed, were requested to report their analgesics consumption at baseline and 1, 3, 6, 9, and 12 months following initiation of HC use. Mixed linear model was used to assess analgesic alterations from baseline.
Results: Study population consisted of 806 patients (459 men; age 49±16 years), with pain duration of 9±9 years for whom HC treatment was approved. Most patients had concomitant pain etiologies; neuropathic pain was the most common one (72%). Data on 806, 756, 630, 549 and 480 patients were available at the five follow-up time points. A significant (P<0.0001) reduction was observed in total amount of consumed analgesics. Generally, an average of 37% of the patients stopped using analgesic agents during the study period (χ²(5)=155.6, p<0.001). Specifically, 55% stopped using over the counter (OTC) analgesics, (χ²(5)=241.1, p<0.001), 55% -non-steroidal anti-inflammatory drugs (NSAIDs) (χ²(5)=263.4), 49% -weak opioids (χ²(5)=200.5), 34% -strong opioids (χ²(5)=194.2) and 43% -anticonvulsants and antidepressants adjuvant analgesics (χ²(5)=195.1 and χ²(5)=227.0, respectively).  
Conclusions: These findings suggest that HC treatment is associated with a long-term sparing effect for all analgesic classes among patients with chronic pain. Further follow-up is needed to substantiate these findings.

ASSOCIATIONS BETWEEN HERBAL CANNABIS TREATMENT AND DECREASE IN ANALGESICS CONSUMPTION: A MULTI-CENTER PROSPECTIVE STUDY OF PATIENTS WITH CHRONIC PAIN