What's the most effective way to prevent contact dermatitis from football helmet?

Coat the area: If the dermatitis is from an irritation, try to get a better fitting one. If the dermatitis is itchy, the reaction may be from a contact allergy to the material which comes into contact with the face (rubber in particular). If you are allergic to rubber , try to find a substitute containing no rubber. If no such substitute is available, try to coat the area with polyurethane or clear nail polish.