Expired SPF could leave you vulnerable to a sunburn and other skin damage.
If you can't remember when you bought the bottle of sunscreen you're using, it's probably best to purchase a new one to make sure you aren't using expired sunscreen.
Yes, SPF does in fact expire, and when it does, it may leave you vulnerable to a sunburn, sun poisoning or other skin damage, according to the Cleveland Clinic. Having effective sunscreen is vital because not only will it keep you from burning your skin, but it'll reduce signs of aging and your risk of skin cancer. So before you head to the park, pool, beach or backyard this summer, it's important to check the expiration date on your sunscreen bottle.
For more, check out the best sunscreens for faces, the best sunscreens for dark skin and the best reef-safe sunscreens.
The Food and Drug Administration mandates that all sunscreens maintain their full strength for three years -- so, if you have leftover sunscreen at the end of the summer (say a heavier type for outdoor adventures), you should be able to safely use it for two more summers.
Some sunscreen manufacturers print the expiration date on the bottle or label, but not all do. When you buy a bottle of sunscreen, check for an expiration date. If it doesn't have one, write the date of purchase in permanent marker.
Also take note of the period-after-opening symbol, which tells you how long a product stays fresh once opened. It typically looks like a jar with the lid off and a number, which indicates the number of months after you open it that it's usable.
Theoretically, if you're using sunscreen in the recommended way -- putting it on any bare skin when you go into direct sunlight for any length of time, and reapplying it periodically -- you shouldn't have much left over year to year.
If you have a bottle of sunscreen that you're not sure about, use your best judgment: When's the last time you remember using that sunscreen? Does the bottle itself seem old? If you think it's over 3 years old, it probably is.
Other hints that your SPF might be ineffective include:
Read also: The Ideal SPF Sunscreen You Should Use This Summer: Not Too High, Not Too Low
Using expired sunscreen won't hurt you directly -- as in, it won't do anything to your skin -- but it could set you up for a gnarly sunburn. And, as you already know, sunburns indicate unprotected sun exposure, which is directly related to your risk of developing skin cancer and premature aging.
The expiration date is there for a reason: to let you know if that sunscreen is still effective. It's always a good idea to buy a new bottle of sunscreen if yours is expired. And if you're into tanning under the sun, try a sunless self-tanner instead.