I was on Clarithromycin Suspension 500mg daily for about two years. I did find it worked for about 18 months or so. I switched back to Azithromycin about six months ago. I like taking the Azithromycin better since I only have to take 500mg three times per week. I hope you have success with the Clarithromycin. I did find this medication upsetting to my stomach if I did not take it with a snack or meal. Good luck to you.