ORIGINAL RESEARCH Effectiveness of water as the neutralising agent for glycolic acid peels in skin phototypes IV-V Irma Bernadette S. Sitohang | Githa Rahmayunita | Vashty Amanda Hosfiar | Shafira Ninditya | Maureen Augustin Department of Dermatology and Venereology, Faculty of Medicine Universitas Indonesia, dr. Cipto Mangunkusumo Hospital, Jakarta, Indonesia ABSTRACT The aim of the study is to evaluate the effectiveness of water as a substitute for sodium bicarbonate plus solution in the neutralisation process of chemical peeling using a 35% glycolic acid solution. This ran- domised, double-blind, split-face, controlled trial was conducted in an outpatient setting. A total of 126 healthy patients with skin phototypes IV–V aged between 18 and 60 years old were recruited. Chemi- cal peeling was performed with 35% glycolic acid solution. One side of the face was neutralised with water, and the other side of the face was neutralised with a sodium bicarbonate plus solution. The main outcome of this study was measured by the degree of erythema, pruritus and pain scores. Significant difference in the pain score immediately after the neutralisation process of the chemical peeling with glycolic acid was seen. However, there were no sig- nificant differences in the degree of erythema or the pruritus score. These results indicate that water can be used as a substitute for sodium bicarbonate plus solution in the neutralisation process of chemical peeling with 35% glycolic acid in patients with skin phototypes IV–V. Key words: chemexfoliation, glycolic acid peel, skin phototypes IV–V, sodium bicarbonate, split face, water. INTRODUCTION Chemical peels are classified according to the depth of penetration of the skin: superficial, medium and deep. The depth of penetration is influenced by the composition, con- centration and pH of the peeling agent, anatomical location, epidermal integrity, skin priming, application technique, occlusion and contact time. 1-5 Superficial peels target the epidermis and the epidermal–dermal interface and cause decreased corneocyte adhesion, partial or complete necro- sis, increased epidermal enzyme activity leading to epider- molysis, and increased dermal collagen deposition. 1,6-14 Superficial chemical peels are suitable for all Fitzpatrick skin phototypes; 4,14 however, patients of Asian descent are more sensitive to skin irritation induced by alpha-hydroxy acids (AHA). 15 Alphahydroxy acids were developed as more superficial peels to treat hyperkeratosis. 16 Subsequently, peeling with glycolic acid, the most commonly used alphahydroxy acids, was developed. 17 Glycolic acid is the most widely used chemical peeling agent worldwide. 2,18 The main advantage of chemical peels using glycolic acid is that it is not absorbed systematically, though it still needs to be neutralised. 19 Neutralisation is the process of applying a weak base solution with a pH ranging from 9 to 10 in the area of the skin where the glycolic acid was applied for 3 to 5 min. 20-22 Water is also known to be a neutralising agent for chemical peeling. 5 Until now, there has been no study comparing the effectiveness of water as a substitute for sodium bicarbonate plus solution in the neutralisation pro- cess of chemical peeling using glycolic acid. METHODS Randomisation, sample size and ethics Block randomisation was performed using a computer- generated random number list prepared by an Correspondence: Irma Bernadette S. Sitohang, Department of Dermatology and Venereology, Faculty of Medicine, Universitas Indonesia, dr. Cipto Mangunkusumo Hospital, Jalan Salemba Raya No. 6, Jakarta, 10430, Indonesia. Email: irma_bernadette@yahoo. com Funding: This study was supported by the research fund from dr. Cipto Mangunkusumo Hospital, Jakarta, Indonesia. The sponsors had no role in the conduct of the study. Conflict of Interest: None. Irma Bernadette S. Sitohang, PhD, Githa Rahmayunita, MD, Vashty Amanda Hosfiar, MD, Shafira Ninditya, MD, Maureen Augustin, MD Submitted 19 July 2020; revised 31 August 2020; accepted 9 September 2020. Australasian Journal of Dermatology (2020) , – doi: 10.1111/ajd.13486 © 2020 The Australasian College of Dermatologists