What are the most important adverse effects of calcium channel blockers?

• A. Hypotension and bradycardia
• B. Nausea and vomiting
• C. Rash and photosensitivity
• D. Dizziness, flushing, headache, peripheral edema, and constipation

Answer: (D)

Calcium channel blockers commonly cause adverse effects that reflect their vasodilating actions and effects on cardiac conduction. The most noticeable and clinically significant of these are dizziness, flushing, headache, peripheral edema, and constipation. Dizziness and headache come from dilation of cerebral and systemic vessels, while flushing also results from skin vessel dilation. Peripheral edema occurs because arteriolar dilation increases capillary hydrostatic pressure, pushing fluid into the interstitial space. Constipation, especially with non-dihydropyridine agents like verapamil, happens due to slowed gastrointestinal motility. Collectively, these effects are frequent across many patients and often guide dose adjustments and patient counseling.

Less common or less characteristic adverse effects include nausea and vomiting or rash/photosensitivity, which may occur but are not as prominent. Hypotension and bradycardia can occur, particularly with certain agents, but the broader and more consistently observed set of adverse effects centers on vasodilation-related symptoms and constipation.