Background: Natural anti dandruff efficacy is an area of interest as there is a consumer need for natural technologies in over-the-counter shampoo formulations.

Aim: This research explored dipotassium glycyrrhizate (DPG) for anti dandruff benefits utilizing in vitro and in vivo methodologies, examining a shampoo formulation with 0.15% DPG.

Patients/Method: The in vitro investigation focused on the evaluation of antimicrobial efficacy of DPG in a shampoo formulation by use of bacteriostatic efficacy testing as well as a short interval kill test against well known dandruff causing microorganism i.e. malassezia. Clinically, 28 female and male subjects possessing visible dandruff were enrolled in a non-comparative study with 1 shampoo formulation containing 0.15% DPG. A trained investigator conducted visual technical assessments evaluating dandruff intensity at baseline and after product use over 2 weeks. A product performance self-assessment questionnaire was also completed for all subjects. The clinical was conducted under the supervision of a dermatologist.

Results: Shampoo formulation with 0.15% DPG showed bacteriostatic efficacy against well known dandruff causing microorganisms i.e. malassezia. The short interval kill test shows that a shampoo formulation with 0.15% DPG is more effective against malassezia furfur (ATCC 14521) compared to the placebo, a non-anti dandruff shampoo. Clinically, a shampoo formulation with 0.15% DPG significantly reduced visible flakes/dandruff after 1, 7 and 14 days of use from baseline and the greatest improvement as compared to baseline was seen at week 2 (P < 0.001) with 90% improvement in reduction of visible flakes/dandruff. The self-assessment questionnaire results correlated to the visual technical assessment results.