Topical capsaicin in painful diabetic neuropathy. Effect on sensory function

To examine the effect of capsaicin on sensory function in painful diabetic neuropathy.

We examined the effects of topical 0.075% capsaicin cream on thermal and vibration thresholds in 22 subjects with painful diabetic neuropathy who participated in a double-blind vehicle-controlled therapeutic trial.

After 8 wk of use, there was no significant change in warm and vibration thresholds, but the cold threshold was significantly reduced by capsaicin and vehicle creams to an equal degree. In fewer subjects who used capsaicin cream in an open-label study, there was no significant effect on sensory thresholds after up to 32 wk of use.

Although our results and those of others show no adverse effects of topical 0.075% capsaicin on human sensory function, even in subjects with preexisting neuropathic sensory impairment, the small number of subjects tested does not justify an inferential statement on safety. Further studies in more subjects are warranted to ensure the long-term safety of capsaicin for pain relief in humans.