 [ Symptoms ] how can i know if my coldflu has become bacterial so i can take a ampicillin  i am aware that ampicillin does nothing if my coldflu is a virus but i have been sick for a week now and although my body is not soreweak anymore i still cough up alot of mucus and coughing hurts my chest a bit and i have a sore throat also runny nose with alot of mucus as well [ Disease ] it would not be wise to self diagnose yourself as having a secondary bacterial infection from your recent viral illness and self prescribed ampicillin it would be advisable for you to be properly examined and diagnosed first by a medical professional ampicillin is not used very much any more so it is unlikely that even if you did have a bacterial infection this would not be the antibiotic of choice signs of secondary bacterial infection such as pneumonia as a result of a respiratory virus would be a high fever a worsening cough with expectoration of dark phlegm chest discomfort rapid respiration and lethargy a mild sore throat or runny nose does not necessarily indicate a need for ampicillin