The prescription domino effect: How one drug's side effects can quietly trigger another

One pill leads to another — and not always for the right reasons. A large Ontario-based study published in the BMJ has identified 24 common "prescribing cascades," where a side effect from one medication is mistaken for a new medical condition, prompting an additional — and potentially unnecessary — prescription. Think NSAIDs raising blood pressure, which then gets treated as a new hypertension diagnosis instead of reconsidering the pain medication.

Older adults are particularly vulnerable, as they're more likely to be managing multiple conditions and juggling several medications at once. Mature women face even greater risk, tending to experience more chronic conditions, more drug therapies, and more adverse drug events over their lifetimes.

Key Takeaways:

• Clinicians should track not just what medications a patient takes, but when each was started and why — a new symptom may trace back to an existing drug
• Pharmacists embedded in prescribing decisions could help catch cascades that physicians might miss
• Automated clinical decision support tools could flag potential cascades at the point of care before another prescription is written

Why it matters: Prescribing cascades are a hidden but common source of drug-related harm — and avoidable healthcare costs. Recognizing the pattern is the first step to breaking it.