Answer:
just read this today, there is an expiration date for sunscreen...older than 3 years throw away. The active ingredients become stale and ineffective.
Yes, it becomes less effective over time. My rule of thumb is to replace it every season. (Once a year.)
wtf no it doesnt
Yes, after a year it won't work as well. If it is from last summer throw it out!
in time, everything dies or expires, so...I'd say yes. One or at most 2 seasons then toss
I read in Teen People magazine that you should replace it every year because over time the active ingregitents become less active and don't protect you as well.
I heard it is only good for one year, but I just picked up another bottle at Trader Joe's which has an expiration date of 2010. So keeping it for over a year shouldn't be a problem considering how expensive some brands are.
After 2 years, or it changes smell or color. The stuff does not officially expire, it degrades. If you have it longer, you need to get out more!
No longer than 1 year, less if it has not been kept in a cool place.
You should also know that you need to apply it 20 minutes before sun exposure for full efficiency.