Sure, we use it — or we should use it — every day, but do we really know everything there is to know about our sunscreen?

Most of us know that sunscreen is a product that can help provide protection against UV rays, sunburns and even help prevent pre-mature wrinkles or age spots. But can any of us confidently say that we are true sunscreen connoisseurs?

Test your knowledge and see if you know these five not-so-well-known facts about sunscreen:

1. “Baby,” “sport,” and “waterproof” sunscreens don’t exist.

These are all simply marketing tactics that sunscreen companies promote in order to convince you to buy their product. No sunscreen is considered to be waterproof or sweatproof (at least, not yet).

If you do find a sunscreen that says it is “water-resistant,” that’s okay. In order to earn the “water-resistant” label, a sunscreen must have research to prove that their sunscreen protects the skin after 40 to 80 minutes of swim or sweat time.

2. Higher SPF isn’t always better.

While a higher number SPF does typically offer a little more protection, the margin of difference is extremely small.

For example, a sunscreen with SPF 30 blocks about 97 percent of UVB rays, while a sunscreen with SPF 50 blocks about 98 percent of UVB rays. Even though the SPF makes it seem as if there is a large difference between 30 and 50, there’s really only a 1 percent difference.

3. You should use a shot of sunscreen every day.

On average, people are only using a quarter to half of the recommended amount of sunscreen. You should be using one ounce of sunscreen to cover your face and body, which equates to the size of a standard shot glass.

Additionally, you should be wearing sunscreen every day, all year around. You can still get burnt by the sun in the colder months, even when you’re inside. UVB is blocked by glass, but UVA — which is the one that causes sunburns — can still come through while you’re sitting at your desk at work or driving in your car.

4. Sun can damage sunscreen.

Think your sunscreen is immune to sun damage? Think again. The potency of sunscreen’s active ingredients can be reduced when exposed to extreme heat. Meaning, the longer it sits out in the sun, the less effective it will be.

To help keep your sunscreen in top shape, store it in a cool container like a cooler or keep it at room temperature.  

5. Reapplying is just as important as applying.

Just because you applied sunscreen 30 minutes before you go outside, it doesn’t mean you’re protected for the rest of the day. By walking around, sweating or hopping in the water to cool off, your sunscreen is going to run off at some point.

That’s why it is critical to keep your sunscreen nearby when you’re spending several hours outside, and make sure to reapply every two hours.

Looking for a more in-depth analysis of the science behind sunscreen? Schedule an appointment with one of our board-certified dermatologists today!