Does SPF expire?

How do you know when to replace sunscreen?

1. 1Check the container for a printed expiry date. Replace sunscreen when that date arrives.
2. 2Look for an open jar symbol with a number and the letter M. On UK sunscreen, this tells you how many months the product lasts after opening. Record when you opened it.
3. 3If there is no expiry date, write the purchase date on the container so you can replace it three years later.
4. 4Check the sunscreen itself before using it, even if the date has not passed.

An open jar symbol is packaging shorthand, not a request to decipher modern art. A printed expiry date and a months after opening symbol answer different questions: check both rather than treating the opening date as a replacement for the expiry date.25

Can sunscreen go bad before its expiry date?

Yes. Heat and direct sunlight can make sunscreen ingredients break down faster, including when a bottle is left in a hot car. Replace sunscreen with an obvious colour change, a different or foul smell, separate layers, or a dry and flaky texture.2

Keep the container away from excessive heat and direct sunlight. When you are outside in hot weather, keep sunscreen in the shade or wrap the container in a towel. Protecting the bottle matters as well as applying its contents: storage helps preserve the product's effectiveness.6

What happens if you use expired sunscreen?

The active ingredients break down, so expired sunscreen cannot be relied on for protection. Expired sunscreen can also cause irritation or an allergic reaction, and bacteria or mould can grow inside the container. Replace it rather than continuing to use it.2

How should you use the replacement?

Choose broad spectrum sunscreen with SPF 30 or higher and water resistance. In the UK, look for at least four stars for UVA protection; UVA inside a circle indicates that the sunscreen meets the EU standard. These protection markings describe what you are buying, while the expiry information tells you when to replace it.45

1. 1Apply sunscreen to dry skin 15 minutes before going outdoors, following the bottle's directions.
2. 2Cover all skin not protected by clothing, including your ears, neck, tops of your feet and exposed scalp. Most adults need about one ounce to cover exposed skin.
3. 3Reapply approximately every two hours outdoors, and after swimming or sweating as directed. Reapply after towel drying or when sunscreen has rubbed off.

A higher SPF does not last longer on your skin or let you skip reapplication. Water resistance is not waterproofing: labels specify 40 or 80 minutes of protection while swimming or sweating. The bottle's shelf life and the protection from one application are separate limits.14

If you have already used expired sunscreen and developed sunburn, stay out of the sun until the redness has gone. Cool the skin with cool water or a cool bath or shower. Seek medical help if you feel unwell or your skin swells badly or blisters. Use shade and protective clothing alongside fresh sunscreen, because sunscreen alone cannot fully protect you.45