Which over-the-counter decongestant can cause blurry vision and diplopia, particularly with high intraocular pressure?

• A. Pseudoephedrine
• B. Diphenhydramine
• C. Acetaminophen
• D. Ibuprofen

Answer: (A)

Pupil dilation and increased intraocular pressure can be triggered by systemic sympathetic stimulation from certain OTC decongestants. Pseudoephedrine is a common example that activates alpha-adrenergic receptors, providing decongestion but also potentially dilating the pupil. In eyes with high intraocular pressure or narrow angles, this dilation can worsen outflow obstruction and raise IOP, leading to blurred vision and even diplopia in susceptible individuals. The other options lack this decongestant mechanism or don’t have the same risk of raising IOP; for instance, anticholinergic medicines like diphenhydramine can cause blurred vision through accommodation effects, but they’re not decongestants, and acetaminophen and ibuprofen don’t typically affect vision or IOP.