Although you may think makeup can last forever if kept closed tightly and stored in a cool, dry place, I've got news for you...negatory! Makeup does expire; as soon as a product is opened, bacteria begin to grow.
Since makeup companies are not required to post expiration warnings on their labels, you have to use your judgement and be informed of the guidelines recommended by experts. It can be difficult to keep your makeup out of the sun and heat but that is what kills the preservatives that help fight off nasty germs.
Also, never use makeup if you have an eye infection. The bacteria can spread and fester and infect everything it touches. Never, ever share your makeup with others. Lastly, discard of any makeup that seems like it has changed color or smells funny. Here is a consolidated list regarding the shelf life of cosmetics.
To see the expiration dates read more