My daughter is taking azithromycin for strep. this is her last day of a 5 day course of meds. she still has redness and pus in the throat. she is 17 years old. while she isn't as uncomfortable, the throat still looks bad.

That should cover: strep. This medication is taken for 5 days, but continues to work for another 5 days, so she still has antibiotic in her system. However,I would expect her to be even better by this point in her treatment. She probably has a concurrent viral infection (one of which could be mono, if she has never had that); please have her rechecked by her doctor.