This is an over-the-counter allergy drop, useful for itching and swelling of the eyelids. This drop actually contains two separate drugs. The first is called pheniramine – this is an antihistamine to decrease inflammation. While effective, it is not as powerful as stronger antihistamines found in newer drops. The other drug is called naphazoline. This is a vasoconstrictor that makes the eyes less red, but can cause a rebound redness when the drop wears off (an effect similar to Visine). Overall, Naphcon-A and the other generic equivalents are effective but I never prescribe them as they are not as powerful as newer allergy drops like Alaway/Zaditor or the prescription drops Bepreve and Pataday.