Tretinoin
"I tried tretinoin 0.05% a year ago and I stopped as it didn't have any effect no side effects either. So I went back to the doctor a month ago and the doctor said it can take up to 6 months before I could see any results but it's worth doing.  So I used the same cream and again I didn't notice any results until 3 weeks which gave dramatic improvement. It hasn't dried out my skin. My advice is stick at this medicine for at least 6 months because it's worth it. Take doxycycline antibiotics at early stages to help with negative side effects of acne getting worse in early stages."