The Brightening Effect of Turmeric Extract (Curcumin) on Lip Color: A Double-Blind Randomized Controlled Trial

Introduction: Curcumin, with its antioxidant and melanogenesis-modulating properties, holds promise for treating lip hyperpigmentation. Thus, this study aimed to assess the efficacy of a curcumin-based lip balm in reducing physiological lip darkness. Methods: In a double-blind, randomized controlled trial, ۵۶ subjects with physiological lip hyperpigmentation were consecutively sampled and randomly assigned (۱:۱) to apply either a curcumin-based lip balm or an identical curcumin-free placebo every four hours for six months. Then, standardized monthly photographs were evaluated by a blinded investigator using a ۰–۵ ordinal lip-color scale. Ultimately, between-group differences and within-group changes were assessed using independent t-tests and paired t-tests, respectively. Results: Participants consisted of ۷ males (۱۲.۵%) and ۴۹ females (۸۷.۵%), with a mean age of ۲۷.۱±۴.۵ years. Baseline lip-color scores were comparable between groups (curcumin: ۳.۵۷±۱.۱۷ vs. control: ۳.۶۱±۱.۲۰; P=۰.۸۷۹). The control group showed minimal early changes, with noticeable improvements starting at month ۳ and a mean reduction of –۰.۹۶ by month ۶ (P<۰.۰۰۱). Moreover, the curcumin group demonstrated earlier improvements from month ۲, achieving a sharper decline of –۱.۸۹ by month ۶ (P<۰.۰۰۱). Between-group differences were nonsignificant through months ۱–۳ (P>۰.۴۷) but became significant from month ۴ (mean difference ۰.۵۰, P=۰.۰۳۱), increasing to ۰.۸۹ by month ۶ (P=۰.۰۰۴). Nonetheless, the results revealed no adverse reactions. Conclusion: The curcumin-based lip balm was safe and provided earlier, more pronounced, and clinically meaningful improvements in lip hyperpigmentation compared to a placebo, with significant superiority emerging from mid-treatment onward.