Which of the following is a common side effect of beta-blockers?

Beta-blockers are a class of medications primarily used to manage conditions such as hypertension, heart failure, and arrhythmias. One of the well-documented side effects of beta-blockers is fatigue. This occurs because beta-blockers work by blocking the effects of adrenaline (epinephrine) on beta-adrenergic receptors, leading to a decrease in heart rate and cardiac output. While this can be beneficial for reducing strain on the heart, it can also result in feelings of tiredness or reduced energy levels in some patients.

In contrast, nausea is generally less common and not directly associated with the mechanism of action of beta-blockers. Insomnia, while possible, is not as frequently reported as a side effect and can vary widely among individuals. Increased heart rate is also unlikely since beta-blockers are designed to lower heart rate rather than increase it. Therefore, fatigue stands out as a typical side effect experienced by patients taking these medications.