Research into medical cannabis in pain relief so far has been limited to only five or six randomized controlled trials and just three cohort studies. They primarily investigated the effects of cannabinoids on the relief of chronic pain that was not alleviated by optimized opioid therapy. But for most patients, the most extreme condition is not necessarily relevant.
Medical cannabis does have some mild adverse effects from cannabinoids when used in cancer treatment. Still, they are generally well tolerated by patients even when the negative effect is moderate.