Purging is a common occurrence when we're treating acne. What happens is that acne appears on the surface of the skin, but in reality a lot of it is below the surface of the skin. As we're addressing acne, we're removing that top layer of skin, getting rid of the acne that is on the surface and allowing that acne that's below the surface to come up. That takes about 4 weeks to actually finish. If after four weeks you're still purging, you're still feeling that your acne is not improving, it's important to see your skin care professional.