In a 67-year-old man with type 2 diabetes who has vomiting and diarrhea and cannot keep fluids down, which of his regular medicines should be withheld temporarily during an acute illness?

In a 67-year-old man with type 2 diabetes who has vomiting and diarrhea and cannot keep fluids down, which of his regular medicines should be withheld temporarily during an acute illness?

• A. Metformin
• B. Atorvastatin
• C. Amlodipine
• D. Lansoprazole

Answer: (A)

In this situation, the important concept is the risk of lactic acidosis with metformin during acute illness that causes dehydration or kidney function decline. Metformin is eliminated by the kidneys, so when someone is dehydrated or has reduced renal perfusion, the drug can accumulate and raise lactate levels. That makes withholding metformin during vomiting/diarrhea with poor oral intake the safest approach. It should be stopped for the duration of the illness and restarted only after rehydration and renal function are back to normal, typically after confirming that the patient can tolerate fluids and has stable kidney function. The other medicines listed don’t have an acute, universal need to stop simply because of dehydration from an illness. They can usually be continued unless there are other specific issues (such as liver concerns with a statin, or hypotension with certain blood pressure medicines).

In this situation, the important concept is the risk of lactic acidosis with metformin during acute illness that causes dehydration or kidney function decline. Metformin is eliminated by the kidneys, so when someone is dehydrated or has reduced renal perfusion, the drug can accumulate and raise lactate levels. That makes withholding metformin during vomiting/diarrhea with poor oral intake the safest approach. It should be stopped for the duration of the illness and restarted only after rehydration and renal function are back to normal, typically after confirming that the patient can tolerate fluids and has stable kidney function.

The other medicines listed don’t have an acute, universal need to stop simply because of dehydration from an illness. They can usually be continued unless there are other specific issues (such as liver concerns with a statin, or hypotension with certain blood pressure medicines).