This paper investigates the role that emotions related to local gender norms play in urban Mexican men's understandings of erectile dysfunction (ED) aetiology and drug treatment by analysing semi-structured interviews with 28 male urology patients. Analysing narrative data from our interviews, the paper examines how these men drew differently from locally intelligible ways of understanding health and masculinity to develop context-specific understandings of causes and potential treatment outcomes. Study participants' feelings of success or failure in life areas relating to the performance of 'responsible' masculinity, especially work and romance, strongly influenced understandings of ED aetiology and goals for drug treatment. Those who felt successful at being men collaborated with loved ones to adopt purely biological understandings of ED causation, while those who expressed negative emotions about their performances of masculinity viewed these feelings, as well as the structural and interpersonal problems that caused them, as key causes and consequences of dysfunction. I discuss how these different emotional experiences led to different ways of using medication, and the relevance of these findings for clinical practice.