I'm 23 and started zithromax last november. Since then its been a great help. I was getting sick with colds,broncitis,flu,etc all the time but after i started it ive had 1 cold and it lasted 4 days and my lung fuction is holding steady. I take 500mg mon,wed,fri....but i hear others take it daily. U'll need to talk to your doctor about wat may be best for u.