What the PAO Symbol Actually Means

You've probably noticed that small open-jar icon on the back of your moisturizer or foundation — that's the Period After Opening (PAO) symbol, and it's more than packaging decoration. The number inside (like "12M" or "6M") tells you how many months a product remains safe to use after you first open it, not from the manufacturing date.

This distinction matters. A sealed lipstick sitting in a drawer for two years may still be perfectly fine once opened, while a mascara you cracked open six months ago could already be a contamination risk. The PAO is an industry-standard guideline based on stability and microbial testing — it's not arbitrary, but it also isn't a legal expiration date in the United States the way food labels are. That said, dismissing it entirely is where things can go sideways.

If you're still building your routine from scratch, our guide for makeup beginners is a great place to start before diving into the details of product longevity.

The Myths vs. The Real Risks

Not every expired product is equally problematic — and not every guideline carries equal weight. Here's where the science actually draws the line.

Myth

All expired makeup is dangerous and should be thrown out immediately.

Fact

Risk varies widely by product type. Dry powders and pencils generally pose far lower contamination risks than liquid or cream formulas.

Bacteria and mold need moisture to thrive. A dry eyeshadow palette or blush that's been kept clean and dry can often remain usable well beyond its PAO without posing meaningful health risk. Liquid products — foundations, concealers, cream blushes — are a different story because their water content and organic ingredients create a hospitable environment for microbial growth once preservatives degrade.

Myth

Mascara is fine to keep using as long as it doesn't smell bad.

Fact

Mascara should be replaced every 2–3 months regardless of smell, because repeated eye contact makes it a high-risk contamination vector.

Every time you apply mascara, you're introducing bacteria from your lashes and eyelid margin directly into the tube. Over time, even a preservative-containing formula can't keep up. Expired mascara has been associated with eye infections, including conjunctivitis. The smell test isn't reliable here — harmful bacteria don't always produce an obvious odor. Ophthalmologists and dermatologists consistently flag mascara as one of the highest-risk makeup products to keep past its recommended window.

Myth

SPF in makeup doesn't really expire — the coverage still looks the same.

Fact

UV-filtering ingredients can degrade over time, meaning expired SPF-containing products may provide significantly less sun protection than labeled.

The FDA regulates sunscreen as an over-the-counter drug, and that includes the SPF in your tinted moisturizer or foundation. Sunscreen actives like avobenzone can break down with age, heat, and light exposure. If your SPF 30 foundation is two years past its PAO and stored in a warm bathroom, it may be delivering a fraction of that protection. This is a genuine health concern — not just a cosmetic one — particularly for people relying on makeup as their primary daily sun protection.

Myth

Natural or preservative-free products last just as long as conventional ones.

Fact

Products without synthetic preservatives often have shorter, not longer, shelf lives — sometimes significantly so.

Preservatives in conventional makeup exist specifically to inhibit microbial growth. "Clean" or preservative-free formulas may use alternative antimicrobial agents (like certain plant extracts or vitamin E), but these are often less effective or shorter-lived. Some natural beauty brands actually recommend PAO windows as short as 6 months for this reason. If you're using preservative-free products, it's worth paying closer attention to storage conditions and expiration cues — not less.

Myth

Lipstick lasts forever because it doesn't touch your eyes or skin the same way.

Fact

Lipstick does contact mucous membranes and can harbor bacteria or become rancid, especially in formulas with oils and waxes.

Lips are a direct route into your body, and lipstick formulas containing moisturizing oils can go rancid — producing a noticeably off smell and potentially causing irritation. Most lipsticks carry a PAO of 12–24 months. Beyond that, rancid oils can cause lip irritation or dryness. It's a lower-risk category than mascara, but "lasts forever" overstates the reality considerably.

2–3 months

Recommended mascara replacement window

Eye care professionals and cosmetic chemists widely recommend replacing mascara every 2–3 months to reduce infection risk from repeated eye contact.

12M–24M

Typical PAO range for most makeup

Most mainstream makeup products carry a Period After Opening of 12 to 24 months, though high-moisture products like liquid liner may be as short as 3–6 months.

Signs a Product Has Genuinely Gone Bad

The PAO is a starting point, but your senses can be just as reliable. Trust these red flags regardless of the date on the package:

  • Separation or curdling in liquid foundation or concealer
  • A rancid, sour, or unusual smell — especially in anything containing oils or emollients
  • Texture changes like gritty mascara, dried-out lip gloss, or clumping powder
  • Color shifts that weren't there when you bought the product
  • Skin or eye irritation that starts after using a product you've had for a while

These aren't just cosmetic inconveniences — they signal that a product's preservative system has broken down or that bacterial growth may have occurred. When in doubt, the cost of replacing a product is always lower than treating an eye infection or a skin reaction.

Never Share Mascara or Eye Liner

Sharing eye makeup is one of the fastest ways to transfer bacteria, viruses, and even conditions like pink eye between people. This risk applies regardless of how new or old the product is. Keep eye products strictly personal, and dispose of any product used near an eye infection immediately — even if it's nearly new.

For a deeper look at what product label language actually guarantees — and what it doesn't — check out our piece on decoding beauty label claims.