A 79-year-old patient with newly diagnosed Alzheimer’s disease is started on Aricept (donepezil) 10 mg once daily. The prescription is written for 10 mg from the beginning rather than starting at 5 mg daily and increasing the dose after the patient has had time to tolerate the medication.
About one week later, the patient begins experiencing significant nausea, GI cramps, and decreased appetite. The patient reports feeling “sick to my stomach” but denies vomiting, diarrhea, fever, or chills. During a telephone encounter, the nausea is attributed to a possible gastrointestinal infection. Zofran (ondansetron) 4 mg as needed is prescribed for symptomatic treatment.
The patient’s nausea temporarily improves with Zofran, but their appetite remains poor. The family reports that the patient has become more fatigued and is eating much less than usual. Nobody initially recognizes that the timing of the nausea closely followed initiation of donepezil at a relatively high starting dose.
Donepezil commonly causes gastrointestinal adverse effects, including nausea, diarrhea, and vomiting (excellent board exam nugget). Starting at 10 mg daily can increase the likelihood of these problems compared with the usual initial 5 mg daily dose. In this case, the nausea is likely a medication adverse effect rather than an infectious illness.
This is a classic example of a prescribing cascade. A new symptom develops after a medication is started, the symptom is attributed to a new medical condition, and another medication is prescribed to treat the new symptom. The second medication may provide some relief while the original problem remains unrecognized.
A simple medication timeline could have helped: donepezil 10 mg daily started → nausea and GI cramping develop within days → nausea treated as a presumed GI infection → ondansetron added. When a new symptom appears shortly after starting or increasing a medication, healthcare professionals should pause before assuming that a new disease process is responsible.
The better question isn’t always, “What medication can we give for this symptom?” Sometimes the more important question is, “Did a medication cause this symptom in the first place?”
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