Even ruthless purgers tend to hold on to lotions and potions for too long. But all items become less effective over time. Throw out anything that smells or looks funny or that you know is well past its prime. Many products have a “period after opening” label, a number followed by the letter M (shown). It indicates how many months the item is effective after opening. In general eye makeup is good for six months, foundation a year, and lipsticks two (but pay attention to preservative-free products, which typically degrade more quickly than others).