Non-stick pans use Teflon, which can cause illnesses over a longer time. Bad quality non-stick coating contain harmful chemicals like PFOA and PTFE, they release into your egg through overheating. Thus, they can damage your immune system in the longer run. For this reason, always buy non-stick pans from renowned brands with proven expertise and assurance of high quality materials. Read: Food Safety of Non-Stick Cookware.