Host: How quickly should treatments for a pinkeye work? Dr. Laura D. Cook: Well, if it's a viral cause of conjunctivitis, the virus has to run its course just like a cold and normally, with a supportive treatment, it's going to take 7-10 days for it to resolve. bacterial conjunctivitis, if treated with the appropriate antibiotic should begin resolution within 24-48 hours. As a side note, even bacterial conjunctivitis is usually self limited, meaning that even without treatment, it will resolve. If it's an allergic cause of conjunctivitis, starting the eye drop, usually depending on how severe it is may take up to three weeks and then lastly, toxic, again it depends on how severe that conjunctivitis is.