Which of the following is a common side effect of diphenhydramine?

Bradycardia refers to an abnormally slow heart rate, which is not a common side effect of diphenhydramine. While some medications can lead to bradycardia, diphenhydramine primarily affects the central nervous system and is more associated with sedation and anticholinergic effects rather than alterations in heart rate.

Hypertension, or high blood pressure, is not a typical side effect of diphenhydramine. Instead, antihistamines like diphenhydramine can sometimes cause hypotension due to their sedative effects and potential to relax blood vessels, but they are not known to raise blood pressure.

Joint pain is not recognized as a common side effect of diphenhydramine. While some individuals may experience discomfort or pain due to various reasons, diphenhydramine is not typically associated with musculoskeletal side effects, as its primary action relates to antihistaminic and sedative properties.