The first rule is, if it starts smelling bad or starts separating, its probably time to throw it out.
Second if you cannot remember when you bought it, its probably good to throw it away. I usually suggest writing the date you bought it or opened it on the bottom of the product. Remember if you are using natural cosmetics that they have a shorter life so check with the company. Here are some guidelines to follow:
Mascara: 3-4 months - As this is used daily around the eye area it is recommended to turn this over the most because of bacteria growth. Not replacing your mascara can lead to eye infections/pink eye.
Eyeshadow: 2 years for powder and 12-18 months for cream - it seems like we never get to the bottom of our eyeshadows as many of us have tons of them, but same as a mascara, bacteria can grow on the shadow.
Lipstick: 2 years
Foundation: 18 months for liquid and if it is oil free then 1 year and 2 years for powder
Blush or bronzer: 2 years for powder and 12-18 months for cream
Lipgloss: 18-24 months
Eyeliner: 2 -3 years for pencil and 3-6 months if liquid
Lipliner: 2 -3 years
Concealer: 12-18 months
Eyebrow pencil: 2 years
Facial cleanser: 1 year for cream or gel formulas
Face cream: 6-12 months
Eye cream: 3-6 months
Nail polish: 1 year - generally speaking you can usually see this getting bad by noticing clumping or thickening of the polish.
Sponges: Wash these weekly and throw away monthly.
Makeup brushes: You can keep these for 10 years if you take care of them properly. Make sure to treat them like your own hair and be gentle with them. Wash weekly.
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