What is one of the concerns associated with the use of first generation antihistamines?

First generation antihistamines are known for their efficacy in treating allergic symptoms; however, one of the prominent concerns associated with their use is the strong anticholinergic effects they can produce. These effects occur because first generation antihistamines can cross the blood-brain barrier, leading to central nervous system side effects such as sedation, dizziness, and impaired cognition. Additionally, peripheral anticholinergic effects can include dry mouth, blurred vision, urinary retention, and constipation, which can be particularly concerning for older adults or individuals with certain preexisting conditions.

Understanding the implications of these strong anticholinergic effects is crucial for healthcare providers when recommending treatment options, especially in populations that may be more sensitive to these side effects. In contrast, options like low cost and availability, rapid onset of action, and high efficacy in treating congestion highlight benefits of first generation antihistamines but do not address the significant concerns regarding safety and tolerability that arise from their anticholinergic properties.