A nurse inadvertently administers 160 mg of valsartan PO to a client who was scheduled to receive 80 mg. Which of the following actions is the priority for the nurse to take?

A. The primary concern after an overdose of valsartan is hypotension, as it can cause significant blood pressure lowering. B. Monitoring urine output is important but not the priority immediately after an overdose. C. Laboratory results are useful but not critical in this immediate situation. D. Nasal congestion is a possible side effect of valsartan but is not as urgent as monitoring for hypotension.