Which of the following is a common side effect of α1 antagonists?

The correct answer identifies a common side effect of α1 antagonists, specifically dry mouth. This occurs due to the mechanism of action of these medications, which inhibit alpha-1 adrenergic receptors. By blocking these receptors, α1 antagonists lead to peripheral vasodilation and decreased blood pressure. However, this blockade can also impact the neural regulation of salivation, subsequently reducing saliva production and resulting in a sensation of dry mouth.

While other choices can potentially be side effects, they are less commonly associated with α1 antagonists. For instance, dizziness may occur due to orthostatic hypotension but is not as specific to α1 antagonists as dry mouth. Similarly, nausea and blurred vision can arise from various medications or conditions but are not characteristic effects of α1 receptor antagonism. Thus, dry mouth stands out as a more specific and common side effect associated with this class of antihypertensive agents.