Diuretics are used to treat a number of conditions including hypertension and edema. Now, imagine Mrs. Jane Doe who is prescribed hydrochlorothiazide, a diuretic, to better control her high blood pressure. In a subsequent check-up, her physician notices that results from a blood sample analysis reveals a high level of uric acid. Hyperuricemia is indicative of gout. In good faith, Mrs. Doe's good doctor decides to prescribe allopurinol, an anti-gout medication that will help reduce uric acid to a more normal level.
In turns out that diuretics are often the source of increased levels of uric acid. It turns out Mrs. Doe's doctor has failed on two counts: 1) he misinterpreted the diuretic's hyperuricemic effect as a new medical condition, that is, gout and 2) there is no need to treat the increased uric acid level unless it becomes symptomatic.
This is an example of the prescribing cascade which leads to the consumption of inappropriate medication. In this case, a better approach would have been to reduce the dose of the diuretic (and/or perhaps add another antihypertensive if needed to regulate blood pressure) or find an alternative medication that is not associated with increases in uric acid.
Many more examples of prescribing cascades exist. As such, before initiating a new medication, all physicians need to ask themselves one important question: 'Is this new medication being used to treat the effects of another drug'.