Background: Side effects of prescribed and nonprescribed psychostimulant use are understudied. Objectives: The study examined side effects of prescribed and nonprescribed psychostimulant use in a college sample with attention to possible gender differences. Methods: 2716 undergraduates (1448 male) between the ages of 17 and 57 years (M = 19.43 years, SD = 1.7 years) completed an online survey that included questions about the subjective side effects of prescribed and nonprescribed psychostimulant use. Results: Results suggested that prescribed users more frequently reported side effects, compared to nonprescribed users. For prescribed users, females more frequently reported appetite, somatic, and anxiety-related side effects compared to males. For nonprescribed users, while females reported more somatic and anxiety-related side effects, males more frequently reported loss of sex drive and sweating as side effects. Conclusions/ Importance: These findings suggest prescribed users of psychostimulants more frequently report side effects with prominent gender differences in line with gender roles.