Diabetic peripheral neuropathy (DPN) is a type of nerve damage associated with diabetes that affects the feet and legs. It results in pain, numbness, and tingling in the extremities. Current pharmaceutical treatment options include antidepressants, anticonvulsants, or opioid medications, which can result in side effects, interactions, and the risk of addiction, abuse, and withdrawal.
Researchers wanted to evaluate the efficacy and safety of capsaicin in DPN. Capsaicin is a chili pepper extract that produces a burning sensation when applied to the skin. It affects the nerves and reduces the activity of pain receptors. The study, published in the Journal of Pain, found that capsaicin treatment provides modest improvements in pain and sleep quality.
About the study
The double-blindrandomized controlled trial included 369 participants with an average age of 63 years old. The participants had painful DPN for at least one year and were also receiving additional treatment, such as medications. The capsaicin was introduced as an additive therapy. Participants were randomized to one 30-minute treatment with either a capsaicin 8% patch or a placebo patch to painful areas of the feet. Study results were measured at 2, 4, 8, and 12 weeks using 0-10 rating scales for both pain and sleep interference.
The reduction in the mean daily pain score was:
- 27.4% for the capsaicin group and 20.9% for the placebo group over 2-8 weeks
- 28% for the capsaicin group and 21% for the placebo group over 2-12 weeks
The improvement in mean daily sleep interference scores was:
- 33.1% for the capsaicin group and 24.2% for the placebo group over 2-8 weeks
- 34% for the capsaicin group and 24.7% for the placebo group over 2-12 weeks
How Does this Affect You?
A randomized trial is considered the most reliable form of research, but how the research is done will affect its reliability. In this study, many participants in the capsaicin group would have known they received some form of treatment given the reaction at the patch site, which was 33.9% in the capsaicin group compared to 8.2% in the placebo group. The most common reaction was burning sensation and pain at the application site. In addition, there may not be a meaningful reduction in pain for all that initial burning. Scales were used to determine average improvement; however, it is questionable whether participants would have noticed the 7%-9% difference between treatment and placebo groups, especially since they were already receiving other treatments to reduce pain. More studies will need to be done to compare capsaicin patches to traditional treatments to determine efficacy.
Other studies have also determined that capsaicin might reduce neuropathic pain. However, it may not be a practical treatment as many patients may not be able to tolerate its burning side effects. A low-dose cream is currently available to treat DPN pain. Talk to your doctor about whether it is right for you and whether the benefits outweigh the side effects.
RESOURCES
American Diabetes Association http://www.diabetes.org/
Family Doctor—American Academy of Family Physicians http://www.familydoctor.org
References
Diabetic peripheral neuropathy. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115259/Diabetic-peripheral-neuropathy . Updated May 18, 2017. Accessed May 23, 2017.
Simpson DM, Robinson-Papp J, et al. Capsaicin 8% in painful diabetic neuropathy: a randomized, double-blind, placebo-contgrolled study. J Pain. 2017 Jan;18(1):42-53. Available at: http://www.sciencedirect.com/science/article/pii/S1526590016302449. Accessed May 24, 2017.