I have been on this medication for 2 weeks now, I see no improvement! My doctor told me that since this is an antibiotic, my acne could only improve but it is just getting worse! I went from having about 5 severe whiteheads to 20 on each side of my face! When I started this medication I had discontinued tretinoin .05% cream a week before. My questions are, is the bactrim causing this "purge" and how long does it take to see positive results? Did the discontinuation of tretinoin aggravate my acne? Thank you for any input.