I have a cough that produces phlem/mucus...possible respiratory infection. dr prescribed me kflex 500mg. taken 3 so far in 24 hrs. will it clear me up?

It should...: Keep taking the antibiotic until it finishes. It should clear up. If it doesn't, then go back to your doctor. But, give it more time. Hope you feel better.

Depends: You should probably not be taking antibiotics unless proven to have a treatable bacterial infection. In a non-smoker what you describe is likely to be viral unless shown to have infiltrates on chest x-ray (pneumonia). You will probably get better in 7 days with Keflex and in one week without it.