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Like a prize-winning boxer, skin-care serums pack a punch. Somewhere between a liquid and a gel, serums are a way for skin-care manufacturers to pack in potent ingredients such as vitamin C and retinol. If you rely on your serum to keep your skin clear and healthy, it’s important to know that the serum can expire and lose its potency over time. While you can extend the life of your serum somewhat, there is a time when it’s best to throw it out.
The Six-Month Rule
Mark the day you open your serum on your calendar: As a general rule, your skin-care products, including serums, will last about six months, according to “Good Housekeeping” magazine. This is because some products contain ingredients, such as vitamin C, that break down after about six months, decreasing the potency of your serum. However, some serum ingredients, such as glycolic acid, get more potent with time, which means your skin could start getting really irritated if you aren’t careful. For this reason, "Good Housekeeping" recommends throwing out products with glycolic acid after six months. As an additional concern for all skin-care serums, bacteria like to come into liquid products with time. You don’t want to put bacteria on your skin, potentially contributing to inflamed pimples.
Where You Store
Serums stored in direct sunlight that contain vitamin C, retinol and/or hydroquinone tend to break down more quickly than those that are improperly stored, according to "Good Housekeeping" magazine. Keep your serums out of direct sunlight because the sun breaks down active ingredients much more quickly. Make the storage container airtight. Screw the cap on as tightly as you can -- but not so tight that you won't be able to open it later -- to prevent air and bacteria from breaking down your serum more quickly.
Up to a Year
There’s always an exception to a rule, and skin serums are no exception. If your serum comes from a pump bottle, it may last up to a year. This is because pump bottles don’t allow the same air in as products with a twist-off cap. Plus, you are applying the product to your hand instead of dipping your finger into the serum.
Watch for Clues
Knowing the signs that your serum may be expired or expiring can save you from a skin-care disaster. If your serum starts changing colors or smells funny, these can indicate it’s time to toss. Observing skin irritation -- particularly with glycolic acid products -- also can indicate your serum has expired.