This Swedish register-based cohort study examined whether asthma, hay fever and allergic dermatitis in late adolescence identified in the early 1970s are associated with antidepressant medication in middle age, between 2006 and 2009. After adjustment for childhood and adulthood sociodemographic characteristics, psychological, cognitive and physical function, and comorbidity, the magnitude of the associations diminished for asthma, while hay fever and atopic dermatitis retained associations. Hay fever and atopic dermatitis in adolescence have potentially important implications for future mental health, while asthma may already have influenced an individual’s ability to cope with stress by late adolescence.