329 J. Cosmet. Sci., 73, 329–344 (September/October 2022) Address all correspondence to Akil Ahmad, siti-h@utm.my aj.ahmad@psau.edu.sa Insights into the Application of Reverse Micelles in Cosmetic Formulations: A Review JOHN PETER VELLU, HASMIDA MOHD NASIR, SITI HAMIDAH MOHD SETAPAR, AKIL AHMAD, SING CHUONG CHUO AND MOHAMMED B. ALSHAMMARI Department of Chemical Process Engineering, Malaysia-Japan International Institute of Technology, Kuala Lumpur, Malaysia (J.P.V., S.H.M.S., S.C.C.) Centre of Lipid Engineering and Applied Research, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, Johor, Malaysia (H.M.N., S.H.M.S., S.C.C.) SHE Empire Sdn. Bhd., Johor, Malaysia (H.M.N., S.H.M.S.) Department of Chemistry, College of Science and Humanities in Al-Kharj, Prince Sattam bin Abdulaziz University, Al-Kharj, Saudi Arabia (A.A., M.B.A.) Accepted for publication December 19, 2022. Synopsis Reverse micelles are aggregates of amphiphilic molecules in nonpolar solvents. They have polar cores surrounded by surfactant head groups that can solubilize various hydrophilic compounds such as dyes, proteins, and antibiotics. They are frequently studied for extraction of organic and inorganic compounds. Advantages of reverse micelles are ease of production, high encapsulation efficiency, and protection of encapsulated compounds. The cosmetic market has been continuously growing over the years as more innovative cosmetics products are released into the market. Reverse micelles can be used as nano-sized carriers to encapsulate various hydrophilic active ingredients in cosmetic formulations. They can be prepared using safe, biocompatible, nontoxic, and biodegradable materials, thus are suitable to be incorporated into cosmetic products. The viscoelastic property and the skin permeation property can be adjusted. Targeted delivery and sustained release of active ingredients can be achieved through proper formulation. In addition to being directly included in formulations, reverse micelle systems are also used for the preparation of active ingredients and the analysis of cosmetic products for quality control. Therefore, reverse micelles show great potential for application in the cosmetic sector. This paper reviews related works in past two decades and provides some insights for future studies to broaden the implementation of reverse micelle systems in cosmetic products. INTRODUCTION Beyond the beauty of the face or attractiveness of the skin is the health of the skin itself. Human beings tend to spend a lot of money on beauty products to improve their individual appearance. In recent decades, skin care has gained increasing attention of people of all ages. This leads to the rise of the cosmetic market around the world. The cosmetic market in Asian countries is one of the fastest growing markets (1). The sum value of global