"i&#039;m 14 years old and i have pretty bad acne which started about a year and a half ago. a year ago, my mom took me to the dermatologist to see what they could do. they prescribed me to monocyline (100mg) once a day. i cleared up in about two weeks and my skin was flawless. after about two months, my acne stared to come back. i got off the pill for about a month and resumed it only to find out it wouldn&#039;t clear up my acne anymore. i stopped using it over the summer and started again once school started but twice a day this time. it stopped breakouts from becoming as bad as they could&#039;ve been but didn&#039;t give me the same result as a year ago. my acne was still bad. all i am trying to put out there is stops working after a while. good luck."