Chris, this question is for you. I have a nasty sinus infection and have been taking Erythromycin (250mg) for six days. I can function again, but the infection is far from gone. Are these antibiotics too wimpy for the job? Also wondering how close Erythromycin is to penicillin since my Dad is so allergic to penicillin that a single dose would kill him. I heard that with an allergy like that you should skip a generation before using that drug again.