Abstract
Background: In recent years alternative medicine such as herbal medicines has been attractive and useful in dermatologic therapy. But there is little scientific information about its therapeutic effects and potential side effects. Objective: We performed this study to assess the whitening effect of the root of Ma Huang. Methods: Thirty subjects were tanned by UVB irradiation on their abdomen and 4 pigmented patches in square were obtained. In a single-blind fashion, participants applied the root extract of Ma Huang to two pigmented patches and vehicle to another patch on the abdomen twice a day, and applied nothing to the other patch for 8 weeks. Participants were followed up every week and checked on a melanin index with a mexameter. We also checked the last clinical improvement 8 weeks after the application of the root extract of Ma Huang. Results: MED of the middle back was 73${\pm}$24.66cmJ/cm$^2$. Melanin index of the abdomen was 473.2${\pm}$16.27. Eight weeks after application, the mean change percent of the melanin index of the right upper and lower squares applied with the root extract of Ma Huang were +0.02%(p=0.96) and -0.16%(p=0.76). The mean change percent of the left upper square applied with vehicle was -0.08%(p=0.89). The mean change percent of the left lower square untreated was +0.20(p=0.65). One-way layout ANOVA showed no difference among four squares. Clinical evaluation of improvement did not satisfy: no change 36%; slight improvement 53%; moderate improvement 9%; marked improvement 2%. Conclusions: The root of Ma Huang did not show the whitening effect on the UVB-induced pigmentation checked by the mexameter but showed slight improvement in visual assessment.