Older adults are at particular risk for drug and herbal interactions because they have multiple health problems that require treatment and are generally more susceptible to adverse drug effects. This study used a database containing self-reported herbal, prescription, and over-the-counter (OTC) drugs concurrently taken by a sample of 58 women who were aged 65 years or older. Drug-drug interactions (DDIs) were identified using a Web-based pharmaceutical program. At least 1 moderate or high-risk DDI was identified in 74% of participants, with 136 total DDIs identified. Fifty-two percent (71) of total DDIs were between prescribed and OTC or herbals, with 63% (45) of these involving nonsteroidal antiinflammatory drugs (NSAIDs). It is imperative that health care providers identify all prescribed, OTC, and herbal drugs taken by their patients and assess all interactions in order to avoid the possibility of adverse drug effects.