Most people do not even realize that sunscreens have an expiration date. There are also other factors to consider which may leave your sunscreen ineffective.
Manufacturers of sunscreens design their products to maintain their effectiveness for up to three years. As sunscreens age, the ingredients that ward off the damaging effects of the sun, begin to lose their effectiveness. So, it’s important that you always check the expiration date on your bottle of sunscreen.
Before you grab last year’s bottle of sunscreen, there is one other factors to consider. If your sunscreen was exposed to extreme temperatures, it may not be effective. Extreme heat will break down the active ingredients in sunscreen. So, if you left your bottle of sunscreen lying on your towel at the beach during the summer, you should probably toss it out. Or, if your sunscreen was left in the trunk of your car during a harsh winter, the cold temperatures may have rendered the active ingredients ineffective. It both cases, you are safer just buying a new bottle of sunscreen.
Dermatologists will tell you that you should never have a leftover bottle of sun screen if you are using it properly. Sunscreen should be applied frequently and you should be using at least one ounce (30 milliliters) each time. That means that if your bottle of sunscreen is 4 ounces (118 milliliters), you should be using 1/4th of it for each application.
The American Academy of Dermatology recommends that you use a sunscreen with a minimum sun protection factor (SPF) of 15. This SPF is recommended for average skin, If you have fair skin, increase the SPF. Sunscreen works best when it is applied to your skin at least 20 to 30 minutes prior to being in the sun. You should also reapply sunscreen every couple of hours while outdoors. And, if you are swimming or exercising, you will need to apply your sunscreen more frequently.
