Sunscreen expires, but the date printed on the packaging is only part of the answer. An unopened bottle stored in a cool cupboard and an opened tube carried through two hot summers have not aged in the same way, even if their labels show the same date.
This matters because sunscreen is not just a cream containing filters. It is a carefully balanced film. The filters need to remain stable, and mineral particles need to stay evenly suspended so the dose spreads consistently across the skin.
Expiry date versus open-jar symbol
UK and European cosmetics usually show one of two date systems.
A printed best-before or expiry date is used when the unopened product has a shorter shelf life. It tells you how long the manufacturer supports the product when it has been stored as directed.
The period-after-opening symbol looks like an open jar marked 6M, 12M or 24M. It means the formula is intended to remain suitable for that many months after first opening. It is not a reminder of when you bought it.
Write the opening month on the bottle if you tend to rotate several sunscreens. For a product marked 12M and opened in May 2026, May 2027 is the outer limit only if it has been stored properly and still looks and smells normal.
What changes inside an old sunscreen?
Organic UV filters are molecules that absorb ultraviolet energy. Formulators stabilise them and test the completed product over its intended life, but heat, light, oxygen and time can still change the formula.
Mineral filters such as zinc oxide and titanium dioxide do not simply “stop working” on a birthday. The larger concern is the emulsion around them. If particles clump or the formula separates, the film on skin may no longer be even.
Preservative performance and the product base also age. Repeatedly opening a jar, touching the nozzle, or adding water introduces contamination and changes the conditions the original testing covered.
Signs that a sunscreen should be replaced
Do not keep using a sunscreen merely because the date has not passed if it has clearly changed. Replace it when:
- oil and water remain separated after shaking
- the texture has become grainy, lumpy or unusually runny
- the colour has changed noticeably
- it smells rancid or different
- the packaging is damaged or the cap no longer seals
- it repeatedly spent long periods in a hot car, on a radiator or in direct sun
A separated product can deliver a patchy dose even if some filters remain active. You cannot judge remaining SPF by looking at it, so visible instability is enough reason to stop relying on it.
Does heat ruin sunscreen?
Heat accelerates chemical reactions and can destabilise an emulsion. A beach bag for the afternoon is normal use; weeks in a glovebox during hot weather are not.
Keep sunscreen out of direct sun when possible. Put it in a bag, wrap it in a towel at the beach, and store everyday bottles in a cool, dry place. The bathroom is convenient but can be warm and humid. Do not freeze it, and do not decant it into a clear travel pot: the original packaging is part of the stability design.
Can you use last summer's bottle?
Possibly, if it is within its date, within the period after opening, stored well and unchanged. But an old bottle is not automatically a bargain.
Correct facial application uses roughly a quarter teaspoon for face alone, or around half a teaspoon for face and neck, though face size varies. Reapplication increases that. A bottle used properly through a sunny season should not remain nearly full.
If yours does, the bigger issue may be under-application rather than expiry. The SPF guide explains dose, UVA markings and reapplication in practical terms.
What about makeup with SPF?
Foundation and tinted moisturiser have the same stability limits as other sun-protection products, but most people apply too little makeup to reach the labelled SPF test dose. Do not stretch an old SPF foundation across another season and assume it replaces a fresh, properly applied sunscreen underneath.
Powder SPF presents an even larger dose problem. It may be useful for limited touch-ups, but it is difficult to apply enough powder evenly to reproduce the labelled protection.
Does expired sunscreen become dangerous?
The usual risk is unreliable protection, not that the bottle becomes acutely toxic on its expiry date. An unstable or contaminated formula can irritate skin, but the central problem is that you cannot know the protection left.
If you have already worn an expired product, do not panic. Replace it, use shade and clothing sensibly, and seek medical advice for a significant burn or concerning skin reaction.
The practical rule
- Follow the printed expiry date when there is one.
- Track the period-after-opening symbol.
- Replace sooner after poor heat storage or any change in smell, colour or texture.
- Keep sunscreen in its original packaging.
- Do not save a nearly empty bottle for next year's holiday.
When buying a replacement, how to choose a sunscreen covers UVA labels, filter systems and wearable textures. A fresh, affordable sunscreen applied generously is better protection than an expensive bottle rationed beyond the life its maker tested.