The best physician to ask when it comes to questions about whether or not you kid is contagious is your pediatrician
. Pink eye is a common term used to describe conjunctivitis which is an inflamed conjunctiva. The conjunctiva is the clear outer lining of the eye. When it gets inflamed, the blood vessels fill with blood causing it to turn red or pink hence the name pink eye. There are many different types of conjunctivitis, but the 2 most common are allergic and viral. Allergic conjunctivitis occurs when the eye is exposed to an allergen. It is often itchy as well as red. Viral conjunctivitis is caused by a virus usually the same types of virus that cause the common cold. Viral conjunctivitis is typically painful and a bit itchy. A rarer type is bacterial conjunctivitis and is a much more serious infection. Sometimes early on its hard to tell if the infection is viral or bacterial. For this reason we always treat for bacterial, even when it is most likely viral. So in your child's case, most likely the antibiotics were just there "in case" it was bacterial. Thus, they might not be doing anything to shorten the infection.
Again, please discuss this with your child's pediatrician. As long as your child's doctor
initially examined him, it should be known how long he should stay away from other kids. As a general rule, 24 hours after the symptoms are completely gone he probably isn't contagious anymore, but that rule is not 100%.