Musculoskeletal pain is often treated with physical medicine therapies. Herbal cataplasms, or poultices, containing rubefacient substances, which result in redness of the skin by causing capillary dilation and an increase in blood circulation, are used to treat painful areas of the body. A cataplasm containing cayenne pepper (CP, Capsicum annuum, Solanaceae) applied to the skin at a painful area provides beneficial analgesic effects through a hyperemic response that involves both epidermis and muscle tissue nociceptor fibers. These authors sought to test the optimal CP concentration for cataplasm preparation by assessing its efficacy on selected functional and mobility parameters and to determine the safety of the treatment by examining the effects of the CP cataplasm (CPC) on biomarkers of inflammation, blood vessel activation, and neuroendocrine stress.
Twenty healthy adults were enrolled in the study. There were 14 females and six males with a median age of 43.2 ± 4.6 years and body mass index below 30 kg/m2 who were moderately physically active. Each participant underwent four CPC applications separated by seven to 10 days. At the beginning of each study visit, before-treatment assessments were done. For each application, two to three CPC patches were placed on the back of each participant from the seventh cervical vertebra down to segment one of the sacral spine. Participants were then covered with a towel and topped with sandbags to assure good contact. After 20 minutes, the CPC was removed, and the outcomes were reassessed.
The various concentrations of CP used to prepare the CPCs were 0% for placebo, 2.5%, 5%, and 10%. The CPC were used in random order over the four study visits for each participant. Assessments were made before and immediately after, 15 minutes after, and 30 minutes after CPC placement. The outcomes measured included cold sensation, skin temperature, blood pressure, sensitivity to light touch, the threshold for pain, and maximal voluntary trunk extension force.
A significant decrease in lumbar back skin temperature was observed for all doses of CP and for the placebo (P=0.000). No significant skin temperature effects were seen for concentration (P=0.869) or interaction (P=0.325) effects. The most significant change in skin temperature was seen immediately after the CPC application. These findings may indicate that other factors responsible for the drop in skin temperature partially counteract the vasodilation and hyperemia observed with the use of CPCs. No significant changes were seen in systolic blood pressure or diastolic blood pressure with any of the CPC concentrations (P>0.05).
Using a 0-10 visual analogue scale, participants rated their feeling of cold at an average of 5 immediately after and 15 minutes after the CPC applications (P<0.032 for all). The immediate changes in cold sensation in the placebo group were not significant. Other findings included decreased sensitivity to light touch for all CP concentrations but not for placebo, no changes in the results of a two-point discrimination test in which participants were asked to report feeling one or two pin touches, decreased sensitivity to pain caused by mechanical pressure when using the 5% and 10% CPC, and a significant drop in maximal voluntary trunk extension force observed with the 10% CPC.
With the 5% CPC treatment, serum concentrations of pro-inflammatory cytokines and an anti-inflammatory cytokine changed over time, though not significantly, and returned to baseline levels within 24 hours after treatment. Serum concentrations of C-reactive protein and albumin did not significantly change during the study.
Considering the results of this study, the authors suggest that the 5% CPC is the best choice for treating painful areas, as no additional effects were seen with the 10% concentration, and the effects were greater than those observed with the 2.5% CPC. The 5% CPC did not cause a significant increase in inflammatory-related biomarkers, suggesting that its 20-minute application had no negative systemic effects.
The authors report no conflicts of interest.
Sarabon N, Löfler S, Cvecka J, Hübl W, Zampieri S. Acute effect of different concentrations of cayenne pepper cataplasm on sensory-motor functions and serum levels of inflammation-related biomarkers in healthy subjects. Eur J Transl Myol. March 2018;28(1):105-116. doi: 10.4081/ejtm.2018.7333.