Background The Drug Burden Index (DBI), a measure of exposure to anticholinergic and sedative medications, has been independently associated with physical and cognitive function in a cross-sectional analysis of community-dwelling older persons participating in the Health, Aging and Body Composition study. Here we evaluate the association between DBI and functional outcomes in Health, Aging and Body Composition study participants over 5 years. Methods DBI was calculated at years 1 (baseline), 3, and 5, and a measure of the area under the curve for DBI (AUCDB) over the whole study period was devised and calculated. Physical performance was measured using the short physical performance battery, usual gait speed, and grip strength. The association of DBI at each time point and AUCDB with year 6 function was analyzed in data from participants with longitudinal functional measures, controlling for sociodemographics, comorbidities, and baseline function. Results Higher DBI at years 1, 3, and 5 was consistently associated with poorer function at year 6. On multivariate analysis, a 1-unit increase in AUCDB predicted decreases in short physical performance battery score of .08 (P =.01), gait speed of .01 m/s (P =.004), and grip strength of .27 kg (P =.004) at year 6. Conclusion Increasing exposure to medication with anticholinergic and sedative effects, measured with DBI, is associated with lower objective physical function over 5 years in community-dwelling older people.