What is a common side effect of systemic antihistamines on the eyes?

Systemic antihistamines are widely used to treat allergic reactions and conditions like allergic rhinitis. One common side effect of these medications is dry eyes, which occurs because antihistamines have anticholinergic properties that can decrease tear production by inhibiting the activity of the parasympathetic nervous system. This leads to a reduction in the aqueous component of tears, resulting in decreased moisture on the surface of the eyes. This can cause discomfort, a gritty sensation, and potential exacerbation of any pre-existing dry eye conditions.

Recognizing the impact of systemic antihistamines on ocular health is important for both patients and practitioners. Managing this side effect may involve monitoring symptoms and potentially recommending lubricating eye drops to alleviate dryness. Understanding the mechanisms behind these side effects can help in developing a comprehensive treatment plan for individuals who require antihistamine therapy for allergies, while also addressing any ocular discomfort they may experience.