PAO or 'Period After Opening' Symbol was introduced on cosmetics labels in 2005 by the European Commission, which requires all cosmetic products with a shelf life of 30 months or more to feature the symbol. Products that have a shorter shelf life than 30 months must include the minimum shelf life or best before date on the label.
While the US currently doesn't require cosmetics to have an expiration date by law, the US Food & Drug Administration holds manufacturers responsible for ensuring their products are safe to use — and determining the shelf life of a product is considered part of their duty to consumers.
· Mascara: 2 - 3 months. Bacteria can build up on the wand and cause eye irritation. Pumping the wand in and out can dry the mascara out faster. Discard sooner if the mascara develops an off smell or becomes clumpy. If you develop any eye irritations, be sure to throw out all eye makeup and start over.
· Foundation: Powder - 18 months. Liquid - 6-12 months. Bacteria can grow in the foundation and cause acne breakouts or skin irritation. If it develops an off-smell, discard sooner.
· Concealer: Powder or stick form - 2 years. Liquid - 1 year. Once again, bacteria can grow causing skin irritation. Toss sooner if color has changed as that indicates it is past its prime.
· Face Powder: 2 years.
· Blush: Powder - 2 years. Cream - 1 year. To promote longevity of powder blush wash your makeup brush regularly to get rid of oil build up from moisturizer and foundation.
· Eye Shadow: Powder - 2 years. Cream - 3-6 months. If, however, you get an eye infection it is recommended to toss eye shadow sooner than other powders as it is in close contact with your eyes.
· Eyeliner: Liquid or gel - 2-3 months. Pencil - 1 to 2 years, as long as sharpened between uses. Like eye shadow, eyeliner can become contaminated more easily and spread the bacteria around, and since you're putting the product close to your eye that's just not good. Pencils last longer if they are sharpened regularly, which physically removes bacterial growth. If a white filmy tip develops on the pencil tip and can't be sharpened off, it is past its prime.
· Lipstick and Liner: 1 year, unless you've been sick, then immediately toss it. Lipstick is past its prime if it is hard and is difficult to spread or develops an off smell.
· Nail polish: Unless it doesn't mix when it is shaken, nail polish is good indefinitely.
· Makeup Brushes: Replace when bristles are falling out. Otherwise clean with lukewarm water and a gentle shampoo/soap weekly to keep them free of bacteria.
Resources:
1. https://www.businessinsider.com/how-to-tell-if-makeup-is-expired-symbol-2017-4#:~:text=The%20PAO%20was%20introduced%20on,before%20date%20on%20the%20label.
2. https://www.home-storage-solutions-101.com/shelf-life-of-makeup.html