Liquid foundations are best used in three to six months, while cream foundations maintain their quality for four to six months. If your foundation is in a wide-mouthed jar, it can be exposed to more airborne bacteria and may need to be replaced sooner. If you notice any change in the color or odor of your makeup, toss it. Keep in mind that you really shouldn’t use any foundation if you’ve had it for more than a year.
To ensure your foundation stays in good condition, store it in a cool, dry place away from direct sunlight. If you have a water-based foundation that dries out before its expiration date, add a couple drops of alcohol-free toner and shake it to mix it — this won’t work on oil-based foundations.