How Often Should You Apply Sunscreen?

sunscreen must be reapplied

How often should you apply sunscreen? If the instructions say "reapply often," does that mean twice an hour or twice a day? It depends on the type of sunscreen, how sensitive your skin is, and what activities you'll be doing.

An Early Start

The first rule of using sunscreen, and one that many people forget, is that it should be applied before you go out into the sun. You should apply sunscreen about half an hour before going outside, to allow it to penetrate the skin and begin to work.

Choosing an SPF Level

No matter how often you reapply your sunscreen, you need to choose the SPF level that's right for you. SPF, or Sun Protection Factor, gives you an idea of how long you can stay in the sun before getting burned. An SPF of 15 lets you stay out 15 times longer than if you didn't have any sunscreen. An SPF of 30 should let you stay out about 30 times as long. But keep in mind that reapplying sunscreen doesn't change the SPF! Reapplying SPF 15 isn't the same as starting out with SPF 30.

How Often Should You Apply Sunscreen?

According to the Australian Academy of Science, you should reapply sunscreen at least every two hours, or every hour if you're sweating a lot. Australia gets a lot of sun and has high rates of skin cancer-so they ought to know!

If you notice your skin beginning to feel tender or turn pink, don't wait for the two hours to be up or you'll soon be needing sunburn relief. Reapply your sunscreen right away, and use a generous amount. Check the expiration date on the bottle to make sure it's still good; sunscreen can lose its effectiveness over time. And give some thought to your skin type, time of day, and time of year. Winter-pale skin will burn faster than summer-tan skin. Mid-day rays are stronger than morning or evening.

A Scientific Suggestion

A few years ago, a researcher in England did a study on when to reapply sunscreen. The research, published in 2001 in the Journal of the American Academy of Dermatology, suggested that sunscreen works best when it's applied before going out into the sun and then again after 15 to 30 minutes of sun exposure. After that, the usual rules for reapplication apply.

Specific Instructions

One way to find the answer to "How often should you apply sunscreen?" is to ask the manufacturer. Unfortunately, manufacturers tend to be vague about exactly how often you should reapply sunscreen. Although cancer information sites often say to "follow the package instructions," those instructions tend to say simply "reapply as needed."

  • Coppertone says to reapply its products "as needed, and be sure to reapply after swimming, perspiring, vigorous activity or toweling off."
  • No-Ad says "reapply sunscreen often, at least every two hours."

Some experts say that gel sunscreens wear off faster than lotions. You may have to experiment with different types of sunscreen to see which ones last longest for you.

Waterproof or Water Resistant?

There's a difference between sunscreens labeled waterproof and water resistant. According to the FDA, water resistant sunscreen must continue to work at the same level for up to 40 minutes in the water. To be labeled waterproof, the sunscreen must maintain its SPF level for 80 minutes.

What this really means is that no sunscreen is truly waterproof. Check the label, and then reapply your sunscreen after about half an hour of swimming if it's "water resistant," or about an hour if it's "waterproof." If you're not swimming but you're sweating heavily, you may want to use these same time estimates to tell you when to reapply.

When Reapplying Isn't Enough

No one knows if there are any long-term dangers of using chemical sunscreens. However, some researchers worry that using sunscreen gives people a false sense of security about staying in the sun. Many sunscreens block UVB rays but do a poor job of blocking out UVA light, which can cause cancer. So even if you don't get a sunburn, you could still be increasing your risk.

Of course, if you have to be out in the sun, wearing sunscreen and reapplying it regularly remains essential. But once you've soaked up some rays, consider heading indoors or sitting in the shade.

How Often Should You Apply Sunscreen?