A prescribing cascade is a sequence of events where an adverse drug event is misinterpreted as a new medical condition, leading to the prescription of an additional, potentially avoidable, medication12. This process can lead to further side effects and unanticipated drug interactions, which may result in further symptoms and misdiagnoses3.
For example, a patient might be prescribed a calcium channel blocker, which can cause ankle edema. If this side effect is misinterpreted as a new medical condition, a diuretic might be prescribed to treat the edema2. In another example, a patient develops a cough after starting an angiotensin-converting-enzyme inhibitor. A cough syrup with guafenasin and codeine is prescribed, leading to lethargy. Levofloxacin is started for presumed pneumonia, which leads to diarrhea, followed by delirium and admission to hospital2.
Prescribing cascades contribute to inappropriate polypharmacy, particularly in older adults2. Patients with chronic conditions and geriatric syndromes that require complex drug regimens are at increased risk for problematic and inappropriate polypharmacy2.
To prevent prescribing cascades, healthcare providers should ask themselves if a patient’s new symptom could be an adverse drug event from a medication they are already taking. If so, they should consider whether the initial drug could be substituted for a safer alternative or if the dose could be reduced, potentially eliminating the need for the subsequent drug therapy2. Deprescribing, or the process of tapering or stopping drugs that may not be indicated, can also be considered when a cascade is identified2.