"read whole thing- i had mild acne before going on doxy, which i took for about 3 months. i wasn&#039;t breaking out quite as much at that point, but i still got occasional blemishes. i&#039;m not sure if the meds caused this improvement but it wasn&#039;t that significant of a difference. i wasn&#039;t breaking out as much but for some reason every single zit that popped up would leave a dark red mark (no scar tissue or indentation, just coloration) and these marks did not fade for months. my cheeks looked as if i had tons of acne even though i would only have one active breakout at a time. i had never heard of doxycycline causing something like this, but i decided to stop the meds and within a few weeks the discoloration drastically improved."