Acne medicine from dermatologist?

Ok so im 16, and my acne is/was pretty bad. I went to the derm and they gave me pills to take and i have seen an improvement. But it seems to have stop improving, like it got to a certain point then it stopped, uhm i've been taking the pills for like a month so i wanna know if you have taken this how long it takes to improve and also if it helps get rid of scares too because that seems to be the main problem right now. thanks :)