It can be tough to part with a favorite and sometimes hard to find, but cosmetics have expiration dates for a good reason. When you keep makeup for too long, it could stop performing the way you expect it to, and it  increases that chances of harmful bacteria.

Makeup Loses Effectiveness Over Time

Mascara dries up, foundation separates, and lipstick becomes grainy over time. When you use these cosmetics past their natural life span, they might not perform like you expect. Once the expiration dates pass, performance declines and you just won’t get the look you want.

Bacteria Buildup Could Damage your Skin

If lack of performance doesn’t convince you to stop using expired cosmetics, perhaps harmful bacteria will. One explanation for this phenomenon is reuse. Every time you dip a wand into your mascara tube, you’re introducing bacteria from your skin to the product. Whenever you use expired cosmetics, you are reintroducing new and old bacteria to your skin and eyes. This could result in irritation, inflammation and redness. For eyes, you could even risk conjunctivitis or other serious infections.

Active Ingredients Break Down

From anti-aging ingredients to sunscreen, beneficial compounds will break down over time. Products containing skin friendly acids for anti-aging will lose their effectiveness in a few months after opening, while those promising a sunscreen lose their potency in under a year. You could be risking a nasty sunburn if you depend on an expired product to protect you.

Adhere to dates on the ends of tubes and bottoms of bottles, and throw away opened mascara and related eye products 3 months after opening. Liquids like foundations can be kept for 6 months after opening and powdered products like eye shadow and blush can be kept for up to 18 months before throwing away. If you notice a change in composition in any product, it is time to throw it away.