Purpose: The purpose of this study was to use a pharmacy claims database to identify associations between and the timing of antidepressant and other medication use by age and sex. Material/Methods: A retrospective cohort study was conducted of the 70,519 members of the Deseret Mutual Benefit Administrators (DMBA) insurance company who were continuously covered from the years 2001-2011. Results: During 2009-2011, 13.3% of males and 21.6% of females had at least one pharmacy claim for antidepressants. Those prescribed one of 25 different drug classifications were more likely than the general population to have used antidepressants the previous year. For all of the drug classifications, the use of antidepressants was significantly more common the same year and the year after the drug was first prescribed. The positive association between antidepressant use and other selected drug classifications generally depended on age rather than sex, with the positive association more pronounced in the youngest age group. Conclusion: The positive association between antidepressant use and other selected drug classifications suggests that depression may both lead to and result from many chronic diseases. This association is the strongest among younger individuals, so this age group proves a valuable target for public health interventions.