How Often Should You Reapply Sunscreen?

If you are planning to be out in the sun for an extended period this summer season, or any season, it is important to know how often you should reapply your sunscreen. Wearing sunscreen is an easy way to protect your skin from sun damage, which can lead to signs and symptoms of aging or worse problems like skin cancer. However, sunscreen is only effective if it is worn regularly and reapplied frequently.

Our patients often ask us when to reapply sunscreen during outdoor activities. Here is how often should you reapply sunscreen, and answers to other questions about sunscreen.

Reapply sunscreen every two hours

Your fun in the sun can be made much safer if you commit to reapplying sunscreen every two hours. The reason is simple: the sun protection factor (SPF) of sunscreen is only considered effective for 80 minutes to two hours after you first apply it. The effectiveness of sunscreen decreases over time due to UV absorption and loss of physical sunscreen on the skin due to sweating, swimming, and friction. All patients run the risk of sun damage if they do not reapply.

You can easily set a reminder on your mobile phone to alert you when two hours is up after your initial sunscreen application. Taking a brief timeout to reapply sunscreen will help keep your skin protected from the sun’s harmful rays and prevent aging and skin damage.

What kind of sunscreen should you use?

It is recommended that patients use a minimum of SPF 30 sunscreen, which should be broad spectrum and labeled as very water resistant for 80 minutes. If you are planning to spend significant time outdoors, then choose a sunscreen that is at least 50 SPF to maximize your protection.

Broad spectrum sunscreen means that it protects against both UVA and UVB rays. The ingredients you should look for in your sunscreen are:

• Zinc oxide
• Titanium dioxide
• Avobenzone

Reapply sunscreen after getting wet, sweating, or toweling off

Reapplying sunscreen every two hours may not be enough if you are sweating, swimming, or toweling off. Each of these activities can cause sunscreen to dissipate from your skin.

If you are planning to get wet or will be in a humid environment, use a sunscreen that is water resistant for up to 80 minutes. Then, make sure to reapply your sunscreen after sweating, swimming, or toweling off in order to stay protected from the sun at the beach, the pool, or while exercising.

How much sunscreen do I need to use?

The Skin Cancer Foundation recommends that you need about 1-1.5 ounces (a shot glass full) of sunscreen to cover your face, neck, trunk, arms, and legs. To measure this amount, one ounce is enough to cover your palm. Most people use about half of the recommended amount of sunscreen, which decreases the SPF and puts you at risk of sunburns and skin cancer.

Is this sunscreen safe for kids?

Sunscreens containing the physical sunblocks zinc oxide and titanium dioxide (not nanoparticles) may be safely applied to children as young as three to six months of age without any concerns about chemical absorption or toxicity. Always consult with your board-certified dermatologist if you have any apprehension about sunscreen or ingredient safety.

Have additional questions about sunscreen?

If you have any additional questions about sunscreen, please do not hesitate to contact our office or check out our website. Enjoy your time in the sun this summer! But please do so safely.