Which is a common side effect of verapamil?

• A. Dizziness
• B. Nausea
• C. Headache
• D. Constipation

Answer: (D)

Verapamil commonly causes constipation because it slows gastrointestinal smooth muscle motility by blocking calcium entry into those cells. This reduction in peristalsis is a well-known, dose-related adverse effect of verapamil and tends to be more prominent with this drug than with others in its class. While dizziness, nausea, and headache can occur due to blood pressure changes and systemic effects, constipation is the most characteristic and frequently reported side effect. Management includes increasing fiber and fluids, and adjusting therapy if constipation becomes troublesome, especially in older patients.