Over-the-counter eye drops designed to reduce redness can actually cause more serious problems.
Researchers at the Cullen Eye Institute at Houston's Baylor College of Medicine found that these non-prescription drops can produce conjunctivitis symptoms, such as redness, swelling and itching.
"Some people experienced a rebound effect, where their eyes became increasingly red," said an ophthalmologist who co-authored the study. "The other problems we found were allergic reactions in the eyes and eyelids and swelling of the eyelids."
Artificial tears, without medications to reduce redness, are safe alternatives, he said.