The overall goal of this study is to compare active high cannabidiol (CBD)/ low (−)-trans-Δ9- tetrahydrocannabinol (THC) cannabis vs placebo cannabis in patients with serious medical disorders. Participants will be referred from clinicians and will come to the laboratory daily (3-5 times weekly) for cannabis (15.76% CBD; 3.11% Δ-9-THC) vs placebo (0.0% CBD/ 0.01% Δ-9-THC). The cannabis will be vaporized or smoked as a cannabis cigarette. The participants can choose which option they prefer. The cross-over design will be used where participants receive 2 weeks of active cannabis vs two weeks of placebo in counterbalanced order, with participants blinded to the condition. The outcome measures primarily include measures of pain, with secondary measures of mood, nausea/appetite, quality of life, and the both the potentially positive and negative subjective effects of cannabis (e.g., high, mellow, anxious, paranoid).