Sunscreen stays fresh for three years and has an expiration date on the bottle. Sunscreen lasts for three years only if stored in cool places.
Sunscreen past its expiration date should be discarded. Sunscreen that has an odd coloration or an unusual consistency is not safe to use even within its expiration date. Those who use sunscreen regularly in the recommended amounts typically do not keep sunscreen from year to year. According to Mayo Clinic, people should use approximately 1 ounce of sunscreen, approximately enough to fill a shot glass, to cover all parts of the body exposed to the sun.