Usually, acne is a sign that something is wrong and your body is having a hard time reacting to it and solving the problem. There is no easy way to tell how long your acne will last. You will just have to start healing yourself and solving your acne problem. I suggest going natural, instead of using medicine, chemicals, and antibiotics. Those will ruin things in your digestive system, and maybe other parts of your body too, which may over all make your acne worse.