Which of the following is a common systemic side effect of beta-adrenergic agonists?

• A. Dizziness
• B. Hypotension
• C. Tachycardia
• D. Miosis

Answer: (C)

Beta-adrenergic agonists stimulate beta receptors throughout the body, and the heart is rich in beta-1 receptors. When these receptors are activated, the SA node speeds up and conduction increases, producing an increased heart rate—tachycardia. This is the most consistent and direct systemic effect you see with these drugs because it reflects the primary action of beta-1 stimulation on cardiac pacemaker activity.

Dizziness can occur but is not as characteristic or direct a result of beta-adrenergic stimulation. Hypotension is not the typical systemic effect of beta-agonists and would usually require other mechanisms. Miosis is a parasympathetic effect, not driven by beta receptor activation, so it doesn’t fit with the beta-adrenergic action.