Study reveals common medications trigger harmful prescribing cascades in older adults

A patient comes in with high blood pressure. The doctor writes a prescription. What the doctor may not realize is that the elevated reading might not be a new condition at all—it might be a side effect of an anti-inflammatory drug the patient started months ago for knee pain. By the time a second medication arrives to treat the blood pressure, the original problem has been buried under layers of prescribing logic that no one has stopped to question.

This pattern, repeated across thousands of patients in Ontario, is the subject of new research published in BMJ. Dr. Paula Rochon, who directs research at the Weston and O'Born Centre for Mature Women's Health at Sinai Health in Toronto, led a team that identified 24 distinct prescribing cascades—chains of medication where a side effect from one drug gets mistaken for a separate illness, triggering another prescription that was never actually needed. The cascades involve common medications: statins, iron supplements, nonsteroidal anti-inflammatory drugs. They are quiet, unrecognized, and they accumulate.

The mechanics are straightforward. A medication produces an unwanted effect. That effect looks like a symptom. A clinician, seeing the symptom, prescribes something to treat it. The patient, now on two drugs instead of one, may experience side effects from the second medication, which can prompt a third. What began as treatment for pain or cholesterol becomes a chain of interventions, each one logically justified in isolation, none of them questioned as a sequence.

Older adults face particular risk. They are more likely to be managing multiple chronic conditions simultaneously, which means they are already on several medications. When a new symptom appears, it becomes harder for both patient and doctor to trace it backward to its actual source. A woman in her seventies on medication for heart disease, arthritis, and diabetes has a harder time knowing whether her dizziness came from the new blood pressure pill or from something else entirely. The complexity obscures the cascade.

Rochon and her international team—researchers from the United States, Belgium, Italy, Israel, and Ireland, along with colleagues at Sinai Health—began with a list of 65 potential inappropriate prescribing cascades developed by 12 expert panelists in internal medicine, geriatric medicine, and clinical pharmacology. They then examined prescription data from ICES, Ontario's health data institute, to see which cascades were most common in the actual population and which posed the greatest risk of harm. That analysis narrowed the field to 24 cascades that warranted attention.

The gap Rochon identifies is not one of malice or incompetence. It is a gap in conversation. Doctors and patients do not routinely sit down and trace the history of each medication—when it started, why, whether the next one was truly necessary. Each prescription makes sense on its own. The sequence, however, often does not. "Our concern is that so often these conversations between the health care prescriber and the patient are being missed, so people don't recognize the sequences of events and that they are connected to one another," Rochon said.

Women over 65 carry an additional burden. They tend to live with more chronic conditions than men of the same age, which means they are prescribed more medications and experience more adverse drug events. The more drugs in the system, the higher the probability that a side effect will be misread as a new problem. The cascades are not random; they follow the contours of how medicine is practiced—one visit at a time, one symptom at a time, without the full picture held in view.

Breaking the pattern requires a shift in how physicians approach medication review. It means asking not just what a patient is taking now, but why each drug was started and whether the next one was truly needed. It means looking at the history, not just the present. For a healthcare system already stretched thin, the stakes are both clinical and financial. Unnecessary medications cost money. They also carry the weight of real harm—adverse events, drug interactions, the cumulative burden of polypharmacy on an aging body. The research suggests that harm is preventable, if only the sequences are recognized.