What is a common side effect of calcium channel blockers?

Calcium channel blockers are primarily used to manage conditions such as hypertension and angina. One of their key pharmacological effects is the relaxation of smooth muscle, which is crucial for dilating blood vessels and lowering blood pressure. This smooth muscle relaxation occurs because calcium ions play a significant role in muscle contraction, and by blocking these channels, calcium influx into the cells is decreased, leading to relaxation.

While the other options may describe effects or symptoms related to other medications or conditions, they do not accurately capture the fundamental action of calcium channel blockers. For instance, increased heart rate may occur as a compensatory mechanism in response to low blood pressure resulting from the use of these blockers, and muscle cramping or dry mouth are not direct or common effects of this class of drugs.

Thus, recognizing the primary effect of calcium channel blockers on smooth muscle allows you to understand their therapeutic use and potential side effects more clearly.