Background <p>Transdermal drug delivery is a noninvasive system that enables continuous drug release and is widely utilized across various therapeutic fields. However, differences in skin structure and physiology between sexes may affect drug absorption and therapeutic effects, raising the question of whether sex-related factors should be considered in precision medicine. Therefore, this review aims to evaluate the clinical significance of sex differences in transdermal absorption by synthesizing existing literature and examining the necessity of a sex-specific approach in the development and application of transdermal formulations.</p> Area covered <p>In this study, sex-related factors that may affect transdermal drug delivery were analyzed based on physiological characteristics, including skin thickness, stratum corneum structure, moisture (water) content, sebum secretion, skin blood flow, and skin surface pH. In addition, existing pharmacokinetic and pharmacodynamic studies on various transdermal formulations were compared to evaluate the effect of sex differences on drug delivery efficiency. In particular, sex differences were minimal in areas where transdermal preparations were mainly applied (e.g. forearms, upper arms, and chest). Although pharmacokinetic differences were reported for some drugs, most variations disappeared after adjusting for individual physiological variables such as body weight and body surface area (BSA).</p> Expert opinion <p>In summary, based on the interpretation of pharmacokinetic and pharmacodynamic results obtained from transdermal medicines available to date, sex differences in transdermal drug delivery may affect some skin structural differences and drug absorption patterns but do not result in clinically significant variations. Thus, separate dose adjustments or transdermal formulation designs based on sex are likely to be ineffective. Instead, prioritizing individual physiological factors (such as body weight, BSA, and skin characteristics) would be more relevant in transdermal drug delivery systems. Therefore, a sex-specific approach in the development and clinical application of transdermal formulations is unlikely to offer significant economic and practical benefits. Future research should focus on optimizing strategies that account for interindividual skin physiology rather than sex differences.</p>