Background: While distinct health issues are associated with breast cancer and related therapies, comprehensive assessment of medication use before and after breast cancer diagnosis compared to age-matched, cancer-free controls has not been reported. Methods: From the 93,338 postmenopausal participants in the Women’s Health Initiative trials, medication inventories by pill container review were serially obtained before and > 3 years (mean 5.3 + 2.1 SD) after early stage breast cancer in 1730 cases matched with 1730 controls on age, dates of initial and follow-up medication inventories, body mass index, and smoking. Number of medications and medication classes (excluding tamoxifen and aromatase inhibitors [AI]) in cases and controls were compared. Results: Medication use (n) was comparable at baseline in both groups and significantly increased at follow-up in both cases (4.12 + 2.73 vs 6.47 + 3.29, P< .0001) and controls (3.92 + 2.59 vs 5.94 + 3.37, P < .0001), with clinically marginal but statistically significant additional medication use 0.53 ± 3.93 by breast cancer survivors (P < .0001). More breast cancer survivors used antidepressants (15.3% vs 12.2%, P = .006) and bisphosphonates and/or calcium/vitamin D (62.2% vs 54.8%, P < 0.001). Use of the following classes did not differ: anti-diabetic, cardiovascular, anti-anxiety, and narcotic and non-narcotic analgesics. Medication use at follow-up inventory by adjuvant endocrine therapy are outlined below. Medication use in breast cancer survivors on tamoxifen was lower than controls while those on AIs used more medications. Conclusions: Reflecting age-related co-morbidities, medication use significantly increases over time in both breast cancer survivors and controls. Overall, breast cancer impact on medication use is limited.

*Adjusted Poisson regression used for test of case-control differences.