21 patients with neuropathic pain received placebo, 2.5%, 6.0%, and 9.4% THC in a randomized order. The primary outcome was average pain intensity over time, and patients were also assessed for sleep, mood, quality of life, and subjective feelings of happiness, relaxation, stress, and feeling high. Adverse effects were also documented. Results indicate that only the 9.4% THC dose significantly improved pain intensity, anxiety and sleep compared to placebo over 5 days, but was also associated with an increased rate of adverse events. There were no significant differences between treatments with regards to mood or subjective feelings.