Expiration Date

Check the tanning lotion container for an expiration date. If there is not one, keep in mind that the U.S. FDA dictates that a sunscreen should remain at its labeled strength for three years from manufacture.

Effectiveness

Use fresh tanning lotion to ensure that it is giving you the protection that you expect. Products used past the expiration date can deteriorate and lose the ability to act as a sunscreen.

Storage

Store tanning lotion according to the package directions. The rule of thumb is to store at room temperature away from heat and light. Failure to do so can result in the tanning lotion losing strength before the normal expiration date.

Danger

Using expired tanning lotion will not harm skin in and of itself. The actual danger is in not getting the proper sun protection.

Time Frame

Tanning lotion will not have time to go bad if used liberally as specified by the American Academy of Dermatology. An application of sunscreen is one ounce. A four-ounce bottle only contains four applications if used to liberally cover all exposed parts of the body as recommended.