Does Sunscreen Expire? What to Look for in a Sunscreen

Medically Reviewed by Dan Brennan, MD on August 17, 2021
4 min read

Before you slather on that sunscreen that’s been sitting at the back of your medicine cabinet, make sure to check the bottle for the expiration date. Many bottles of sunscreen have an expiration date printed on them to show when it stops being effective.

The Food and Drug Administration requires that sunscreens keep their original strength for up to three years. Knowing this, you can probably use the same bottle of sunscreen if it’s left over from previous summers.

If your sunscreen doesn’t have an expiration date printed on the bottle, write the date on it in permanent marker when you buy it. That way, you know exactly how long you have to use it. Store your sunscreen at room temperature to ensure it stays in good condition. If you notice that the sunscreen has changed in color and consistency, it’s best to throw it out and buy a new bottle.

Before you buy that next bottle though, here are some things to keep in mind to help you choose the best one for you.

The first thing that you want to look for when you pick a sunscreen is whether or not it is broad-spectrum. Sunscreens that are broad-spectrum protect against harmful UVA rays from the sun. UVA rays penetrate the skin deeper than UVB rays. They are the ones that are responsible for wrinkles and aging due to sun exposure.

When you look at the label, broad-spectrum sunscreens should contain these ingredients:

  • Zinc oxide
  • Octocrylene
  • Avobenzone

The next thing to consider is the sunscreen’s SPF, or sun protection factor. This measures the sunscreen’s ability to protect your skin from the sun’s UVB rays. The SPF is based on the amount of time it takes for your skin to burn when you wear sunscreen compared to skin with no sunscreen applied.

This means that if you normally burn after 15 minutes, for example, applying SPF 30 sunscreen allows you to be protected up to 30 times longer than if you weren’t wearing any sunscreen.

Experts agree that you should go with a sunscreen that’s minimum SPF 30. Sunscreens that are marked above SPF 50 usually don’t provide that much more protection than SPF 50 does. It’s important to keep in mind that if you’re in the water or sweating, the sunscreen’s ability to protect you will be lower, no matter the SPF.

The intensity of the sun’s UVB rays could be different depending on your location. Also, no sunscreen can completely block out all UVB rays. The effectiveness of sunscreen is as follows:

  • SPF 30 blocks out 97% of the sun’s UVB rays
  • SPF 50 blocks out 98% of the sun’s UVB rays
  • SPF 100 blocks out 99% of the sun’s UVB rays

Not all sunscreens are water-resistant. Look for sunscreens that are labeled “water resistant” as these can withstand both sweat and water activities. With these products, the SPF lasts for about 40 minutes, but sunscreens that are very water resistant can last up to 80 minutes. After this, it’s time to reapply.

It’s important to remember that these sunscreens are only water resistant, not waterproof. If your skin is wet or sweaty, it’s important to reapply your sunscreen frequently to avoid sunburn.

The ingredients in your sunscreen depend on which kind you pick: chemical or mineral.

Chemical sunscreens: These are the more common type. They contain a number of chemicals that work together to prevent your skin from burning, but research suggests that these same chemicals can enter your bloodstream through your skin. It’s not currently known if these chemicals have any long-term effects on our health.

Some chemicals that filter out UV rays, like octinoxate and oxybenzone, have been shown in studies to alter hormonal levels in animals. So far, this research has not shown the same effect in humans, but the FDA considers the importance of sunscreen to outweigh the risks of the chemicals in them.

Mineral sunscreens: If you want to avoid unnecessary chemicals, opt for a mineral sunscreen. These are also called natural sunscreens. The main ingredients in mineral sunscreens are zinc oxide and titanium dioxide, which researchers agree are both effective and safe. These ingredients block the sun’s rays and reflect them off your skin.

While these sunscreens have safe ingredients, some research suggests that these sunscreens don’t protect as well as traditional chemical sunscreens.

When you apply sunscreen, you should use about one ounce to cover up any exposed skin. This is the size of a standard shot glass and will fill up your palm. If you choose a sunscreen that’s broad-spectrum, water resistant, and SPF 30 or higher, you should apply your sunscreen at least 15 minutes before heading outside.

There are several kinds of sunscreen, such as:

  • Gel
  • Cream
  • Lotion
  • Spray
  • Stick 

Whichever kind you prefer is up to you as long as you use enough and reapply at least every two hours.

It’s important to wear sunscreen even on cloudy days since UV rays can go through clouds and reach your skin. Because of this, apply generous amounts to your face, neck, and ears each time you go outside, every day.