A red eye can be a sign of several problems or irritations. It could be the start of pink eye a virus in the eye that can itch really bad or even be painful. Pink eye is very contagious. A red eye could be the signs of an eye infection sometimes caused by extending the wear of contacts. A red eye could be a sign of allergies. Allergies can cause a red eye sometimes followed with an itch. If your eye is red and has any other problems call your local opthomalogist or optometrist for an appointment.