44 J. Cosmet. Sci., 74, 44–62 (January/February 2023) Address all correspondence to Ana Raquel Madureira, rmadureira@ucp.pt The Multidisciplinary Process of Developing an Alcohol- Based Hand Sanitizer from Scratch CLÁUDIA CASTRO, INÊS PINTO-RIBEIRO, ISABEL PEREIRA, MARIA JOÃO CARVALHO, CLÁUDIA POPOV, DIANA TAVARES-VALENTE, HELENE R. MOREIRA, JOÃO C. FERNANDES, MANUELA PINTADO AND ANA RAQUEL MADUREIRA Amyris Bio Products Portugal Unipessoal Lda., Porto, Portugal (C.C., I. P-R., I.P., D. T-V., H.R.M., J.C.F., A.R.M.) Universidade Católica Portuguesa, CBQF -Centro de Biotecnologia e Química Fina – Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal (M.J.C., C.P., M.P.) Accepted for publication May 25, 2023. Synopsis Alcohol-based hand sanitizers (ABHS) have always been used in settings that require rigorous hand hygiene, but due to the COVID-19 pandemic, they are now also used by the general population. Considering the increase in demand for ABHS, the goal was to develop a formulation with plant-based and eco-friendly ingredients without compromising performance. Several formulations were developed, and ABHS F#8 was the final result. Skin hydration, transepidermal water loss, and pH were measured in vivo after application of this formulation. An improvement in skin hydration and capacity to retain water — and a normalization of the pH to 5.7 — were observed. The ABHS antimicrobial efficacy was assessed following European standards, and the formulation was classified as bactericidal, virucidal, and yeasticidal. To confirm the formulation’s safety for daily use, two tests were performed: an in vitro skin irritation test and an ex vivo topical application followed by a cell viability test. F#8 was considered nonirritant and safe for the epidermis and dermis. The formulation was submitted to a sensory consumer evaluation in a hospital and was considered better than the benchmark. In conclusion, the authors developed a formulation with plant-based emollients that has antimicrobial activity while improving skin health and is sensorily pleasant to consumers. INTRODUCTION The skin of the hands protects individuals against infectious organisms and toxic agents, but it is also responsible for the transfer of microorganisms between people and surfaces (1). Therefore, hand sanitizers are widely used in hospitals and other occupational settings that demand frequent hand hygiene (e.g., food production settings). There are several types of hand sanitizers, but alcohol-based hand sanitizers (ABHS) are among the most commonly used and effective ones, due to their rapid antimicrobial efficacy, convenience of use, and good tolerance on the skin (2). These hand sanitizers can be more effective than traditional hand washing with soap/detergents, because they require less time for application, are faster