I’ ve had the severest form of acne possible....and have lived with it for probably more than10 years....
Tried a dozens a of dermatologist with no lasting effect....They probably prescribed for me all possible oral and topical treatments I thought...
But these medications gave only a temporary effect...and I could never leave without these medicines...Try try, thinking next morning my skin will be better....

But finally I met a doctor to whom I am really grateful....Dr. S S Trasi, she is from Mumbai...I consulted her at Hirananandani hospital, mumbai....

She put me on Isotroin and a no. of oral medications including some antibiotics....advised me to apply clingard(clindamycin phosphate). In addition they did glycolic peels for me every week for 2 months....
and followed by 5 sessions of laser....
Within  two months my acne was gone...and with laser scar appearance improved...
Obviously I cannot probably have a  completely smooth clear face but, I am not getting new acne any more which is itself a great satisfaction for me....
Though I must have spent around 20k on this treatment I think its fully worth....

I would like to add.....restrictions on diet cannot help reduce acne nor are they the cause.....
I dont put any restritions on my diet now still I havent got it back which proves that...

Yes using a mild glycerine soap helps, rather than using these face washes and harsh soaps...
Drinking water, I dont know how much it helps acne control, but it helps  keep  constipation at bay...

I would advice to get rid of acne meet an experienced dermatologist, rather than any doctor....May be take advice from your family physician on whom to consult...