Adverse Effects of Furosemide in Elderly Patients

A 65-year-old female patient with a history of heart failure is prescribed furosemide (Lasix) for the management of edema. During a follow-up visit, the patient reports increased weakness and dizziness, particularly when standing. As the nurse, you recognize that these symptoms may indicate a potential adverse effect of the medication. Considering the patient's age and current medication, which of the following adverse effects should you prioritize in your assessment?