INTRODUCTION:Sex-based medicine, which can be defined as the process of understanding the inherent differences in disease pathophysiology and response to medications that exist between the sexes, seems like a necessary step in the movement towards personalized medicine. While there are strict guidelines for weight-based dosage of pediatric medications, similar guidelines do not exist for the treatment of adults, despite prominent biologic differences between the sexes. The lack of individualization is of particular importance in the treatment of adult patients in the emergency department (ED), because it can determine the trajectory of a patient's stay at the hospital. OBJECTIVES:This review was conducted to better understand the need for and possible benefits of altering drug dosing guidelines for different categories of medications in the ED. PubMed, SCOPUS, and Google Scholar were queried using a combination of the keywords "gender differences," "sex differences," "treatment," and "emergency". Abstracts, unpublished data, and duplicate articles were excluded. DISCUSSION:In considering some of the most common causes of ED visits, the majority of diseases demonstrate differences in morbidity and mortality between female and male patients, despite similar treatment regimens. These differences can be attributed to variations in drug pharmacodynamics and pharmacokinetics, which may be affected by sex-based biologic variations in body mass index and body composition, and physiologic variations such as hormonal changes, menstruation, pregnancy, and lactation. Regardless of the mechanism of these differences, there is overwhelming evidence that universal drug dosing results in suboptimal outcomes for both male and female patients. CONCLUSIONS:Female sex is a risk factor for clinically significant adverse drug reactions, which range from cutaneous reactions to major bleeding, and can have long-standing implications on patient outcomes. However, future studies are needed to understand the exact pathophysiology of these sex differences, after controlling for potential confounding factors such as demographic differences and provider bias in treatment.