Student loan debt has become a growing crisis. Considering that women are more likely than men to take on student loans and more likely to take on larger amounts, we examine whether the effects of student loans on young adults' mental health and substance use differ by gender. Participants: We used the National Longitudinal Survey of Youth 1997 (NLSY97) data collected from 1997 to 2015. The NLSY97 consists of a nationally representative sample of American youths born between 1980 and 1984. Participants included 2,607 men and 3,004 women who reported college enrollment. Methods: We analyzed data using hybrid regression models. Results: Student loans have more negative effects on young men than young women, in terms of mental health problems, smoking, and heavy drinking. Particularly, young men tend to increase substance use in response to cumulative loan amounts. Conclusions: Borrowing patterns and the health consequences of student loans are gendered.