Does Sunscreen Expire?
Yes, it does! The active chemicals found in almost every brand and type of sunscreen lose their effectiveness after about three years. This means you should be cautious of any bottle of sunscreen you’ve had for longer than three years, even if it doesn’t have a printed expiration date.
Why Some Sunscreens Expire Sooner
While the active UV-blocking chemicals and reagents in sunscreen lose their effectiveness after three years, some sunscreens may have a printed expiration that occurs much sooner. Why? Sometimes, a particular brand’s formula uses an ingredient that will expire faster than the UV-blocking chemicals. This is particularly true for sunscreens containing natural essences and extracts.
If your sunscreen is beyond its expiration date, you should always replace it, even if it’s been less than three years. If a certain chemical or extract in the sunscreen formula expires, it can change the composition of the entire formula, which means the UV-blocking agents could also be rendered ineffective.
Why You Should Always Run Out of Sunscreen
Since your sunscreen’s active agents are effective for three years, you can usually use any standard sunscreen left over from last summer onto the next as long as other ingredients included don’t make it expire sooner. However, in general, you should finish off bottles of sunscreen relatively quickly if you live an active lifestyle outdoors. Skin experts from the Mayo clinic indicate an average sized adult needs about one (1) ounce of sunscreen (enough to fill a standard sized shot glass) for one thorough application. If you buy standard-sized sunscreen bottles, you should go through a bottle within a few weeks of spending full days in the sun, since you apply your sunscreen twice for each day outside.