A HISTOLOGICAL COMPARISON OF 50-PERCENT AND 70-PERCENT GLYCOLIC ACID PEELS USING SOLUTIONS WITH VARIOUS PHS

BACKGROUND. Seventy percent glycolic acid solutions are being commonly used as superficial chemical peeling agents. The pH of these solution s ranges from 0.08 to 2.75. The histologic effects of these various pH solutions on human skin have not been studied. OBJECTIVE. The histolo gic effects of several commercially available glycolic acid solutions at various pHs were examined. METHODS. Test areas of seven glycolic ac id solutions were applied to facial skin of two patients. The skin was not prepped for a peel prior to the application of the acid. The solu tion was left in place for 30 minutes, then neutralized. After 48 hour s, a 2-mm punch biopsy was performed and examined histologically. RESU LTS. The peeling solutions with a pH below 2 demonstrated the potentia l to induce crusting and necrosis, which was not seen with the partial ly neutralized solutions with a pH above 2. The higher concentration a cids (70%) created more tissue damage than the lower concentration (50 %) when comparing solutions with free acid. CONCLUSION. This study dem onstrates that chemical peeling with a 70% free glycolic acid creates move tissue damage than a free glycolic acid. When using a 70% glycoli c acid solution, the lower pH products (below pH 2) create move necros is than the partially neutralized products with a pH above 2. At this rime there is no evidence that creating necrosis leads to a more favor able result of the peel. Therefore, the use of partially neutralized g lycolic acid solutions seems prudent, since they have a better safety profile than low pH solutions, which contain only free glycolic acid.