How long after starting antibiotic is pink eye contagious ?

It Depends: If the pink eye is caused by bacteria and the drops have effective antibiotics, then it is thought 24-48 hrs eliminates the contagion. Since the drops are ineffective for viral pink eye, as long as the eye is red, the infection is probably contagious.

10-14 days: Use of antibiotics does not shorten the contagious stage, the drops shorten the time you have to deal with goopy eyes.