A 45-year-old man with a persistent cough is taking multiple medications. Which medication is most likely causing his symptoms?

The presence of a persistent cough in this patient is most likely due to the use of lisinopril, which is an angiotensin-converting enzyme (ACE) inhibitor. One of the most common and well-recognized side effects of ACE inhibitors like lisinopril is a dry cough. This occurs due to the accumulation of bradykinin, which is a peptide that can cause irritation in the respiratory tract.

Patients often report this cough as a bothersome side effect, and it can be persistent enough to interfere with daily activities. In contrast, the other medications listed are less commonly associated with cough. Amlodipine, a calcium channel blocker, is typically used to manage hypertension and does not have cough as a side effect. Aspirin, while sometimes irritating to the stomach, is not associated with cough. Clonidine, an alpha-2 adrenergic agonist used for hypertension, is also not linked to causing a cough.

Thus, in the context of this patient who is experiencing a persistent cough and is on multiple medications, lisinopril stands out as the agent most likely responsible for these symptoms.