Based on evidence from one systematic review and four small RCTs, nabilone appeared to be safe and efficacious for the treatment of PTSD-associated nightmares, and for pain and spasticity for up to nine weeks of treatment. However, evidence of safety and efficacy beyond nine weeks is currently lacking. Patients with PTSD reported improvements in distressing nightmares and well-being while undergoing treatment with nabilone relative to treatment with placebo.¹⁰ Improvements in pain and quality of life were also observed in other conditions.^7,11,12 While adverse effects were common, they were not categorized as serious and were frequently related to the central nervous system. However, study authors noted that larger trials of longer duration were needed to replicate or confirm the results, given the limited durations of active treatment and limited numbers of included participants. No literature was identified that compared long-term and short-term use of nabilone in PTSD or other chronic conditions. As such, the durability of treatment efficacy remains uncertain and it is unclear if some adverse effects may improve over time with extended treatment.