Out of date sunscreen

[cwilliams2010]

How can you tell when your sunscreen is no longer effective - ie past its sell by date? I know that an obvious way is by smell but if they smell okay even after a year or two would they still be effective?

How long would you recommend keeping a sunscreen from the date which you bought it?

Why don't many have expiry dates on them?

Thanks

[Professor_Brian_Diffey]

If stored carefully, sunscreen can retain its effectiveness for several years. Providing it is a uniform consistency when you squeeze some out, you can use it with confidence. Sunscreen deteriorates when it is stored somewhere hot, such as on the parcel shelf in the back of a car when the sun is shining in, or contamination, such as sand, gets into the bottle.

I would recommend keeping a sunscreen for no more than 2 years.