Most condoms have expiration dates printed on the packaging. Avoid using a condom after it has passed the expiration date because it will start to break down and become much less effective at preventing STDs and pregnancy.
It's not just the expiration date that matters, though. Sometimes condoms haven't been stored properly and the material breaks down before the expiration date. If a condom ever seems dry, sticky, or stiff when it comes out of the package, don't use it. Instead, get a new condom.
It's best to store unused condoms in a cool, dry place where they won't get creased (not in a wallet or pants pocket) or dried out. And never use oil-based lubricants such as lotion, massage oil, mineral oil, petroleum jelly, or baby oil with condoms because these substances can break down the material.