More older adults are taking over-the-counter drugs and supplements with their prescription medications than ever, and as many as 15% of them may be in potentially life-threatening combinations, according to a new study reported in JAMA Internal Medicine.

The researchers conducted descriptive analyses of a longitudinal, nationally representative sample of community-dwelling older adults aged 62–85 years. In-home interviews with direct medication inspection were conducted in 2005–2006 and again in 2010–2011.

The number of older adults who used at least one prescription medication slightly increased from 84.1% in 2005–2006 to 87.7% in 2010–2011. Concurrent use of at least five prescription medications increased from 30.6% to 35.8%. Although the use of over-the-counter medications declined from 44.4% to 37.9%, the use of dietary supplements increased from 51.8% to 63.7%. In 2010–2011, approximately 15.1% of older adults were at risk for a potential major drug-drug interaction, compared with an estimated 8.4% in 2005–2006.

The findings emphasize the importance of oncology nurses taking a full medication history and specifically asking patients about their use of supplements and over-the-counter medications.