What is the most common systemic side effect of topical beta blocker use?

The most common systemic side effect of topical beta blocker use is primarily cardiovascular effects. Beta blockers, when administered topically, especially in the context of treating conditions like glaucoma, can be absorbed systemically despite their local application. This systemic absorption can lead to a variety of side effects, with cardiovascular effects being the most notable. These may include bradycardia (a decrease in heart rate), hypotension (low blood pressure), or other cardiac dysrhythmias.

Although CNS effects can occur given the role of beta blockers in the central nervous system, they tend to be less frequent compared to the cardiovascular manifestations. Systemic absorption may affect the lungs, particularly in patients with reactive airway diseases, but pulmonary effects are typically not as common as cardiovascular effects. Gastrointestinal effects, while possible, are also less frequently reported in relation to beta blocker usage.

Therefore, the understanding that beta blockers primarily influence the cardiovascular system helps clarify their commonly noted side effects in the context of topical administration.