More than one in five older Americans take medications that risk major drug interactions, according to a study published in JAMA. Researchers analyzing data from U.S. adults aged 62 to 85 found that simultaneous use of multiple prescription drugs and dietary supplements has grown, even as overall interaction risks show a modest decline.
Polypharmacy and Supplement Use Climb Among Older U.S. Adults
Nationally representative data from the National Social Life, Health and Aging Project were evaluated for the research, which was headed by Dima Mazen Qato of the USC Schaeffer Center for Health Policy and Economics and the USC Mann School of Pharmacy and Pharmaceutical Sciences. Supported by the National Institute on Aging, researchers compared medication and supplement patterns between 2015-2016 and 2021-2023.
The findings show that polypharmacy—defined as taking five or more prescription medications at the same time—rose from 31 percent to 35.7 percent. At the same time, dietary supplement polypharmacy increased from 12.6 percent to 16.7 percent.
Dr. Spencer Kroll, a physician with expertise in pharmacology, noted that the simultaneous growth in prescribed medicines and dietary preparations creates significant pharmacological challenges. From a pharmacological point of view, this is alarming because each additional chemical entity increases the pharmacokinetic and pharmacodynamic complexity of the aging body,
Kroll told Newsweek.
Prevalence of Major Drug Interactions and High-Risk Medication Classes
Although the study observed a decline in potentially major drug-drug interactions from 25.7 percent down to 22.3 percent during the study period, researchers emphasized that more than one in five older adults remained at risk during 2021-2023.
The medication classes most frequently involved in potentially major interactions remained consistent over time. Antidepressants, statins, and antiplatelet therapies were the most commonly used medications appearing in high-risk combinations.
“These are essential medicines for managing the health of the cardiovascular system and the mental health in older populations, so we can’t avoid them. But it also requires the greatest caution because interactions between these drug classes can lead to severe complications, such as increased bleeding and reduced metabolism.”
Dr. Spencer Kroll, physician with expertise in pharmacology, via Newsweek
Patient harm and a greater chance of toxicity can arise from slowed metabolism, even when drugs are correctly prescribed to better health outcomes.
Prescribing Cascades and Systemic Healthcare Fragmentation
Beyond direct drug interactions, older adults face risks from prescribing cascades, which occur when a medication side effect is mistaken for a new medical condition, leading to another medication being prescribed unnecessarily. A separate study published in The BMJ examined 24 potentially inappropriate prescribing cascades in a large Ontario study.
“Prescribing cascades can be difficult to recognize because the original adverse effect may resemble a new medical condition.”
Paula Rochon, MD, FRCPC, MPH, director of research at the Weston and O’Born Centre for Mature Women’s Health at Sinai Health in Toronto, via Medical News Today
Rochon added that recognition is further complicated by variable timing, as some cascades develop within weeks while others develop over several months. Studies indicate that women tend to face a heavier load of multiple medical conditions, which frequently leads to higher prescription counts compared to men.
Experts note that structural flaws in the healthcare system exacerbate these challenges. Kanwar Kelley, MD, JD—co-founder and CEO of Side Health in Orinda, California, who was not involved in the study—pointed to systemic fragmentation. Patients often see a number of doctors, none of whom have access to the full record and limited communication. Common symptoms such as swelling, constipation, dizziness, nausea, and poor sleep are frequently dismissed as being due to aging rather than evaluated as potential adverse drug reactions.
Public Health Challenges in Geriatric Care
While experts welcome the modest decline in potentially serious drug-drug interactions, the continued exposure of over one-fifth of the elderly highlights an ongoing public health challenge. Better medication reviews, clinical decision-support tools, and greater involvement of pharmacists are cited as ways to help clinicians recognize potentially inappropriate prescribing cascades.
“As the population grows older, our patients’ health and independence will depend increasingly on the ability to negotiate these complex interactions in a safe and sensible manner.”
Dr. Spencer Kroll, physician with expertise in pharmacology, via Newsweek