As a general rule, a facial moisturiser should not be kept for more than 6 months. Some ingredients, like essential oils and botanical actives, may shorten the shelf life even more. Also, if your moisturiser contains SPF, the level of sun protection could decrease over time. Store your creams cool and dry; and with well closed lids. Preferably utilise a spatula, rather than your fingers, when extracting the product.
Liquid foundations are usually water based, meaning they provide great living conditions for bacteria. While an unopened bottle could last for up to two years; as soon as it has been opened, you should replace it after 6 to 12 months. Keep your product away from humid environments, like the bathroom, and heat, as this encourages development of germs. Any change in smell or colour, or if the product separates, indicates that the formula has perished.
Powders (such as facial powder, blush or contouring powder) usually do not contain any water, and, theoretically, this makes them last longer than cream or liquid products: up to 24 months after opening. Bear in mind though, that your makeup brush could still take on impurities and moisture from other products; and bring them back to the powder pot. Take your time to let one product dry before applying the next; and make sure to cleanse your brushes on a regular basis.
Any products that are applied around the eyes are repeatedly in contact with a mucous membrane, meaning that they could easily pick up bacteria and then transfer these back to the eye again. This applies also to eyeliner and eye shadow, but pay extra attention to your mascara, as the tube provides a proper germ hotbed. Replace your mascara every three months to be safe; or if it develops a distinct, gasoline like smell, indicating it has gone bad.
As they usually do not contain any water, lipsticks are among the more long lasting makeup products. However, given the repeated contact with the mouth area, lipsticks are quite prone to attracting bacteria and impurities, which then flourish over time, in the case. Generally; replace your lipstick after a year, or if you have been ill. Also pay attention to odour and texture; and tuck the product if it smells stale or if it gets hard and crumbles.