How Often Should You Reapply Sunscreen?

Sunscreen is an effective way to protect your skin and prevent sunburn, premature skin aging, and skin cancer. But dermatologists note that to get the full benefits, sunscreen needs to be reapplied throughout the day.

Jump to Key Takeaways.

When to Apply and Reapply

Apply sunscreen with these time considerations:

• Apply sunscreen before going outdoors during the day, even on cloudy days, to cover all areas of skin that may be exposed.
• Wait 15 minutes after applying sunscreen before going out into the sun. 
• Reapply sunscreen every two hours when you are outside during the day, regardless of the product’s sun protection factor (SPF) rating. This is the best way to keep your skin protected. If you don’t reapply, you lose the protection for your skin.
• After exiting the water, if you are swimming or bathing, reapply sunscreen
• After sweating, reapply sunscreen.

For sunscreen labeled water resistant or very water resistant (these are terms regulated by the Food and Drug Administration):

• Water-resistant: Reapply after 40 minutes in the water.
• Very water-resistant: Reapply after 80 minutes in the water.
• Please note that no sunscreen is completely waterproof.

Reapplying every two hours is needed because sunscreen can:

• Rub off onto your clothes or towel
• Wash off due to sweat or being in water
• Break down in sunlight 
• Clump after being on the skin awhile and become less effective

Why Is Sunscreen Important?

The sun gives off ultraviolet (UV) rays. These rays can have negative effects on your skin, even on cloudy days. There are two main types of UV rays:

Sunscreen helps block these rays, but it doesn’t last indefinitely on your skin. That’s why reapplying it is just as important as applying it in the first place.

How Much Sunscreen Should You Use?

Studies suggest that the proper amount of sunscreen to cover the whole body is 30 milliliters (mL), or 1 ounce, which is the amount in a full shot glass.

Be sure not to miss spots that will be exposed but are easy to overlook, including:

• Ears
• Back of the neck
• Tops of feet
• Back of hands
• Scalp (especially if you’re bald or have thinning hair)
• Lips

What SPF Should You Use?

SPF stands for sun protection factor. It tells you how well a sunscreen protects against UVB rays. An SPF of 30 blocks about 97% of the UVB rays from the sun. This is the SPF usually recommended. No sunscreen will block 100% of the UV rays.

Using higher numbers of SPF does not mean it lasts longer and needs to be reapplied less often. No matter the SPF number, it should still be reapplied every two hours.

In addition to SPF, make sure you choose a sunscreen that is broad-spectrum. This means that it protects against both UVA and UVB rays.

Tips to Make Reapplying Easier

Try these tips to make reapplying sunscreen easier:

• Set a timer on your phone every two hours, especially when at the pool or beach.
• Keep sunscreen in your bag, car, or backpack so it’s always within reach.
• Use products you like, as the best sunscreen is one you’ll actually use.

Key Takeaways

• Use SPF 30 or higher broad-spectrum sunscreen whenever you will be outdoors during the day.
• Reapply sunscreen every two hours, or every 40 to 80 minutes if you’re in water, and upon exiting the water or after sweating.
• Use enough sunscreen to fully cover your skin, and don’t forget any easy-to-miss spots.