i was on minicyclin for a year and then like mustang, my body became tolerant of it so I saw a derm. for it. He switched me to ADOXA - which works even better, and gave me differin cream (acid like retin-a) and a cyndclimyican cream (antibiotic) for the day time. acne is minimal to nothing. great treatment. It was either that or annesteem (accutane) at 10mgs a day for 10 months..