An examination of the phenol-croton oil peel: Part I. Dissecting the formula

This article investigates which ingredients are the active ones in the most popular peel formula. The benefits of the "phenol" peel have been attributed to the effects of phenol on the dermis. Baker published a simple peel formula in 1962 that became a classic that has been used since by almost all plastic surgeons and dermatologists. Brown et al., in 1960, passed along a set of dogmas: (1) phenol is the active ingredient; (2) phenol peels more deeply in lower concentrations; and (3) adding a surface tension-lowering agent increases the peel. This article seeks to dissect the Baker formula by removing the croton oil. A patient was peeled serially with 18% phenol, 35% phenol, and 50% phenol solutions containing Septisol (surface tension-lowering agent) but no croton oil. This showed that increasing concentrations of phenol caused more clinical tissue reaction as evidenced by edema and erythema, but no significant dermal injury was seen. USP 88% phenol without Septisol did cause injury to the dermis. To test the effect of croton oil in the formula, the patient's face was peeled with two variations: the perioral area was peeled with 50% phenol to which croton oil was added to a strength of 2.1% and the remainder with 50% phenol without croton oil. The perioral area showed vesiculation, slough, and dermal exposure characteristic of a deep peel requiring 11 days to heal. The remainder of the face treated with 50% phenol without croton oil showed only edema and erythema without significant dermal injury. This experiment shows that the main postulates of Brown et al.--that phenol in lesser concentrations peels more than in higher concentrations and that phenol is the sole agent--are not true. In a fourth peel, a 0.7% concentration of croton oil in 50% phenol was applied to the parts of the face not peeled with croton oil in the third peel. The areas peeled with 50% phenol with 0.7% croton oil healed in 7 days, whereas the treatment with 50% phenol with 2.1% croton oil required 11 days. Deconstructing the Baker formula reveals fallacies in the four-decade-long belief system regarding these peels. The serial peels performed in this study show that increasing concentrations of phenol without croton oil cause increasing skin reaction but insignificant peeling effect. The addition of croton oil to 50% phenol, however, causes a marked increase in the depth of peeling into the dermis. Lowering the concentration of croton oil caused a lesser burn, as evidenced by fewer days to heal. The depth of the peel, therefore, seems to be more dependent on the concentration of croton oil than phenol. This will be further explored in Parts II, III, and IV.