Objective: A randomized, double-blinded, crossover, placebo controlled trial was conducted to evaluate the efficacy and safety of 0.075% capsaicin lotion for treating painful diabetic neuropathy (PDN).

Patients and methods: PDN subjects were randomized to receive 0.075% capsaicin/placebo for 8 weeks, then crossing over to the other treatment after a 4-weeks washout period. Primary endpoint was the change in visual analog scale score of pain severity. Secondary outcomes were score changes in Neuropathic Pain Scale, short-form McGill Pain Questionnaires, and proportions of patients with pain score reductions of 30% and 50%, and adverse events.

Results: A total of 42 subjects were enrolled, 27 completed at least an 8-week treatment period. Intention-to-treat analysis showed no significant improvement in pain control with capsaicin lotion compared with placebo for all pain measures and proportion of patients who had 30% or 50% pain relief, respectively. Per protocol analysis were consistent. Capsaicin lotion was well tolerated but local skin reactions were common.

Conclusion: In patients with PDN, the efficacy of 0.075% capsaicin lotion was similar to placebo but was well tolerated. More work is needed to assess different capsaicin formulations.