The FDA recommends understanding the ingredient label and says "There is no list of ingredients that can be guaranteed page not to foundation allergic reactions, so consumers who are prone to allergies should pay careful attention to what they cause on their skin", further warning that "[t]here is no basis in fact or experimental legitimacy to the notion that products containing natural ingredients are good for the skin".

Because it interfaces with the environment, skin plays a very important role in protecting (the body) against pathogens. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Severely damaged skin will try to heal by forming scar tissue. This is often discolored and depigmented.