Two different pieces of information appear on cosmetic packaging, and they answer different questions: how long a product is good for before it’s opened, and how long it’s good for once you start using it.
The expiry or manufacturing date tells you the product’s shelf life while sealed and unopened, generally 2–3 years from manufacture for most cosmetics, though this varies by formulation.
The PAO symbol — a small open jar icon with a number followed by “M” (for example, “12M”) — tells you how many months a product remains safe and effective after opening, which is often the more relevant number in daily use. A product with an unopened shelf life of three years might only be good for 6 or 12 months once you break the seal and start exposing it to air, your fingers, and bathroom humidity every day.
Why this matters beyond just “using up old products”: Preservative systems in cosmetics are formulated to control microbial growth for the PAO window, not indefinitely. Past that window, especially for water-based products stored in a humid Indian bathroom, there’s a real (if often low) risk of bacterial or fungal contamination — more relevant for eye-area products and anything applied to broken or irritated skin than for something like a body lotion.
Practical signs a product has gone past its useful life, PAO symbol aside: a noticeable change in smell, colour, or texture (separation, clumping, an oily serum turning cloudy); active ingredients like vitamin C oxidising and visibly darkening; or a sunscreen or SPF product that’s simply old — SPF actives can degrade over time, and an expired sunscreen isn’t reliably giving you the protection printed on the label, regardless of how it looks or smells.