Other studies show similar results. Like I thought this was not supposed to happen when you're on birth control?! Scared this is going to make my acne worse than before I was on it! This is despite wearing a clean mask every single time. Yaz , like all BCPs , do cause fluctuations in your hormone levels for 3-4 months when you first start them and also when you first end them. I've never experienced anything like this before and did not change my diet or gained weight or anything like that.