Teflon is a chemically stable and nontoxic material at temperatures up to 500 ⁰ F or 260 ⁰ C. At temperatures above 660superscript F or 350 ⁰C, it begins to show considerable amount of decomposition. The products released on decomposition are toxic in nature and sometimes nonbiodegradable. In other words, these decomposition products cause biological harm to birds and flu to human beings. To avoid such ill effects, it is suggested that Teflon-coated cookware should never be heated empty. It has also been found that one of the chemicals, perfluorooctanoic acid (PFOA), used in the manufacture of Teflon, can be carcinogenic in nature. Nevertheless, a Teflon product in finished form does not contain PFOA.

Studies have indicated that heating Teflon may produce harmful gases, such as CFCs, which depletes the ozone layer and causes global warming.