I once used roaccutane (some derivative of vitamin a) that cleared my acne completely. Now, many years later, I'm starting to relapse, so I thought I wanted to try over-the-counter vitamin a. I took 4400 micrograms/day (1500 IU) for 30 days with zero results. I took before and after photos each week or so and compared them carefully. Nothing, it's not working at all. I have superficial acne, not cystic.