How To Cure Facial Pimples ?

i am getting pimples on my face from past 3 months and on my back from last 2-3 years.I consulted a doctor today and she gave me doxycycline and lactic acid bacillus capsules;a strip of antioxidents,multivitamin,multimineral and methylcobalamin tablets;Clindamycin phosphate gel USP;Benzoyl Peroxide gel BP;Dermadew Soap and Ketoconazole solution for dandruff.So i just wanted to know how long will it take to clear all the pimples?