Background: Deep type of melasma is difficult to treat. Various compositions for peeling have been formulated to accomplish this.
Objective: Our purpose was to determine the safe use of the new formula, which was composed of phenol and castor oil.
Methods: Different concentrations of phenol and castor oil were mixed in five formulations, and the solutions were tested on the forearms of 10 volunteers. The application time was 1 minute, different from that of the original phenol-croton oil. Formula 4 was found to cause a high effect of peeling with least side effects and was used to treat deep facial melasma in 30 patients.
Results: Higher concentrations of castor oil produced more inflammation when mixed with phenol. Formula 4 was used to clear two cases of melasma in 1 week despite no effect from prior use of a modified antimelasma cream, while some degree of fading was noted in other cases. The total number of different melasma indices was reduced from 206.4 to 91.2 in 30 patients. Hyperpigmentation was noted in five cases and hypopigmentation in one case. Neither scar formation nor cardiac arrhythmia was observed.
Conclusion: A phenol-castor oil peel with an application time of 1 minute reduces pigments in the deep type of melasma with least side effects and a high efficiency when combined with an antimelasma cream. The safe formula and the technique of application are introduced.