Concomitant dietary supplement and prescription medication use is prevalent among US adults with doctor-informed medical conditions.

Information on patterns of concomitant dietary supplement (DS) and prescription medication (PM) use among US adults is limited. Thus, the prevalence of concomitant DS and PM use as a function of doctor-informed medical conditions (DIMC) was determined in a cross-sectional, observational study of a nationally representative sample of noninstitutionalized, civilian adults aged ≥20 years in the United States (N=9,950) from the 2005-2008 National Health and Nutrition Examination Survey (NHANES). Data were weighted for the complex, multistage, probability sampling design. Approximately one third (34.3%) of all US adults reported concomitant DS and PM use (approximately one in three adults). The prevalence of use was significantly higher among those with vs without a DIMC (47.3% vs 17.3%). Adults with a DIMC were more than two and a half times more likely to concomitantly use DS and PM than adults without a DIMC, after adjustment for sex, age, education, and household income. Multivitamin plus other ingredient(s), followed by antacids and multivitamin plus botanical ingredient(s), were the most prevalent DS categories used with a PM among those with and without a DIMC. The most prevalent PM categories used with a DS were cardiovascular agents (among those with a DIMC) and hormones (among those without a DIMC). These findings demonstrate that presence of a DIMC may be a risk factor for concomitant DS and PM use among US adults. Multivitamins containing nonvitamin or mineral ingredients are more commonly used than standard multivitamins with PM by US adults. This may be an emerging trend that warrants further consideration.