Bathroom and skincare

Does sunscreen really expire? A calm guide to bathroom product expiration dates

9 minute read

Bathroom products are some of the easiest items to forget about. Unlike food, they rarely smell wrong. Unlike medicine, the consequences of using them past prime are usually invisible. So tubes, jars, and bottles accumulate quietly under sinks for years.

Most of those products do, in fact, have expiry dates. But the system for finding them is different from food, and most people have never been told how to read it.

The PAO symbol: why most cosmetics show months, not dates

Look closely at almost any skincare or cosmetic packaging and you will find a small icon: an open jar, with a number followed by "M" (for months). That is the PAO symbol, or Period After Opening. It tells you how long the product is considered good for after you first open it, not from the date you bought it.

Common PAO values:

• 3M: mascara, liquid eyeliner
• 6M: many liquid foundations, eye creams, some serums
• 12M: most lotions, body washes, conditioners, lipsticks
• 24M: many shampoos, body lotions, soaps, perfumes
• 36M: some powders and sealed solid products

The PAO is a manufacturer estimate of when preservatives can no longer guarantee microbial safety in normal bathroom conditions. It is conservative for some products and generous for others. Either way, the day you open the bottle matters more than the day you bought it.

Sunscreen is different because it has a real expiry date

In the US, EU, UK, AU, and NZ, sunscreens are regulated as either over-the-counter drugs or therapeutic goods. That means they carry an actual expiration date, not just a PAO symbol. Most sunscreens are stable for around three years from manufacture if stored properly.

The active UV filters degrade over time. Heat speeds this up dramatically, which is why a tube left in a glove compartment over a hot summer can lose its rated SPF much earlier than the printed date suggests.

Practical advice for sunscreen:

• Use it past the date only if you have absolutely no alternative, never as a regular practice.
• If a sunscreen has separated, gone watery, smells off, or has changed colour, replace it.
• Store sunscreen indoors, not in a hot car or beach bag for extended periods.
• Realistically, if you are using enough sunscreen on a regular basis, you should run out before it expires. If you have a tube that is years old, you are not using enough.

Skincare ingredients that degrade fastest

Even within the PAO window, certain ingredients lose effectiveness sooner than others. If you are paying for the active, you want to use the product before the active is gone.

Vitamin C (L-ascorbic acid)

Notoriously unstable. Once oxidised it turns yellow, then orange, then brown. By the time it is dark amber, it has lost most of its potency and may even cause mild irritation. Buy small bottles you can finish in 1–3 months, and store in a cool, dark place.

Retinol and retinoids

Light- and air-sensitive. Products in airless pumps or opaque tubes hold up much better than those in jars. Once oxidised, retinol becomes much less effective. Generally good for around 6 months after opening.

Benzoyl peroxide

Loses strength over time, faster after opening. Older tubes deliver less of the active ingredient.

Sunscreen actives

Both chemical and mineral filters can degrade with heat and time. Already covered above.

Probiotic or peptide formulas

Sensitive to temperature and humidity. Store as the manufacturer recommends, which sometimes means refrigeration after opening.

Natural / preservative-free products

Often have shorter PAOs (3–6 months) because there is less protection against microbial growth.

Mascara, liquid liners, and anything used near the eyes

Eye products are the category where expired matters most beyond skincare results. The applicator goes near a sensitive area and back into a warm, moist tube. Bacteria grow.

Replace mascara every three months. Liquid eyeliner similarly. If you have had an eye infection while using a product, replace it once you recover. Powder eyeshadows last much longer because they are less hospitable to bacteria.

Storage matters more than people think

Bathrooms are warm and humid, which makes them one of the worst places to store expensive skincare. Heat and humidity accelerate degradation. A few small habits make a real difference:

• Keep vitamin C, retinol, and serums in a cool, dark cupboard rather than a sunny shelf
• Close lids fully each time. Most degradation is from air exposure.
• Do not store sunscreen in a car for extended periods, especially in summer
• Use a clean spatula for products in jars, instead of fingers, to slow microbial contamination
• If a product comes in an airless pump, keep that packaging because it dramatically extends real-world shelf life

How to do a 10-minute bathroom audit

1. Pull everything out of one drawer or shelf at a time.
2. Anything visibly separated, crusted around the lid, smelling rancid, or changed colour: discard.
3. Anything you have not touched in 12 months: question whether it earns its space.
4. For anything you are keeping, check the PAO and write the open date on the bottom in marker if it is not already there.
5. Sunscreens specifically: check the printed expiry, not the PAO.
6. Move products you actually use to the front. Anything kept "just in case" goes to the back or out.

Most people end up discarding 20–40% of their bathroom collection on a first audit. After that, repeating the audit twice a year is enough.

Common mistakes

• Treating the manufacturing date as the open date. The PAO clock starts when you first open the product, not when it was made.
• Trusting a product because it "looks fine." Many actives degrade silently. Vitamin C is the obvious counterexample because it browns visibly.
• Hoarding samples and miniatures. These accumulate fast and almost never get used in time.
• Sharing eye and lip products. Even with a tissue between people, this introduces bacteria.
• Storing sunscreen in beach bags or cars year-round. Sun and heat exposure can shorten its useful life by months.

The goal is not minimalism. It is not paying for inactive product.

You do not need to throw out everything older than a year. The point is to know what is past prime so you stop relying on a product that is no longer doing its job. That is especially true for sunscreen, where the cost of an underperforming product is not just wasted money, it is sunburn.