Most people recognize that when the top of their toothpaste tube looks a little green or gets a little crusty, it’s probably time to replace that toothpaste. And with sunscreens, the manufacturer puts expiration dates on the sunscreen, and we discussed the meaning of those expiration dates all the way back in episode 3 of DermTV. But what about skin care products such as moisturizers and eye creams which have no expiration dates and for which the manufacturer doesn’t tell you how long the product is good for, how do you know when to replace those products? The answer is very simple—as long as the cream or lotion looks the way it should, then that skin care product is probably good but, if the water has separated out on top of the cream, then that skin care product is no longer good and, if that happens, you can’t treat it the way we treat orange juice by just shaking it up to make it all miscible again—the water won’t go back into that cream, so that skin care product should then be replaced.