If your child has breathing difficulties such as wheezing with shortness of breath, a blue tinge to the skin or lips, you should seek immediate advice from a physician. Many episodes of viral illness can last longer than 5 days. Post nasal drip can trigger a cough, and keeping the nasal passages clear can help. Nasal saline is sometimes just as effective as the over the counter cough medications. The antibiotic will only treat bacterial rather than viral illnesses. For any high fever or worsening symptoms, I would advice seeing your pediatrician.