Rule of thumb is once opened, if it's a liquid or gel, get rid of it in 4-6 months or by the expiration date. If it is unopened, then it is still good up to the expiration date. If your product doesn't have an expiration date, and you've had it in your possession over 6 months.... throw it away.
Anything that goes near mucus membranes should always be thrown away after an infection or illness. Anything like chapsticks, lipsticks, glosses, etc should be thrown away after a cold especially when they've been used. you can build up bacteria from illness and keep giving it to yourself. If you have a cold sore, throw away the product, you can spread them.
Always store your products in a cool dry place... NOT THE FRIGE or FREEZER. those can actually cause degredation of the products since most contain fats.