Melatonin for neuropathic pain: a double-blind, placebo-controlled, randomized, crossover trial

Neuropathic pain (NP) is a common challenging problem, and there is a growing need to develop safe and effective nonopioid treatments. Sleep disturbance is commonly associated with NP because pain intensity of NP conditions is often worse at night. Some evidence suggests that the pineal hormone, melatonin, may reduce pain in clinical settings. We conducted a clinical trial to evaluate the efficacy of melatonin for NP. Using a double-blind, placebo-controlled, crossover design, 31 adults with NP were randomly allocated to 1 of 2 sequences of treatment with melatonin and placebo. During each of 2 treatment periods, participants took capsules containing melatonin or placebo for 4 weeks, followed by a 7-day washout period. The primary outcome was mean daily pain intensity (0-10) at maximally tolerated doses (MTD) during each period. Secondary outcomes, assessed at MTD, included adverse events, and measures of sleep, mood, and quality of life. Thirty-one participants were recruited, and 30 participants completed both treatment periods of the trial. The mean maximal tolerated dose of melatonin in this trial was 11.9 mg/day. Treatment-emergent adverse events with melatonin were infrequent and not statistically different from placebo. At MTD, mean daily pain (standard error) was 4.1 (0.3) for melatonin and 4.2 (0.3) for placebo ( P = 0.8). There were no statistically significant differences between placebo and melatonin for any secondary outcomes. Overall, the results of this trial do not provide any evidence to suggest promise for melatonin as an effective treatment for NP.