Out of all the topical retinoids offered to me through my 12 years with acne this has been the most effective. My acne is extremely resistant to treatment and I've been on Accutane twice but this kept it at manageable levels. If starting out with this, only use it a few nights a week. It's drying and irritating. Each time I've gone back to using it I've had an extreme initial breakout / purge which is so difficult to deal with but overall it's my favourite topical I go back to again and again.