How often should you reapply sunscreen?

Do not wait two hours after swimming

Reapply straight after leaving the water and after drying yourself with a towel. Water washes sunscreen off, and towel drying can remove it too. The cooling effect of water can also make you think you are not getting burned.2

Choose water resistant sunscreen for swimming or activities that make you sweat. On US labels, water resistance lasts for either 40 or 80 minutes of swimming or sweating, depending on the product. Follow that limit rather than waiting for the usual two hour interval. No sunscreen is waterproof, and all sunscreens eventually wash off.3

How to apply and reapply sunscreen

1. 1Start with a broad spectrum sunscreen, which protects against ultraviolet A and B rays, with SPF 30 or higher and water resistance.
2. 2Apply sunscreen to dry skin 15 minutes before going outdoors. For a prolonged outing where burning is a risk, NHS advice is to apply it 30 minutes before leaving and again just before going out.
3. 3Cover all exposed skin generously. Most adults need about one ounce to cover skin not covered by clothing. For the face, use at least one teaspoon.
4. 4Include the ears, neck, tops of the feet and exposed scalp. Protect the lips with a sunscreen lip balm with SPF 30 or higher.
5. 5Reapply generously every two hours outdoors, and sooner after swimming, sweating, towel drying or rubbing it off. Check the bottle for its specific directions.

Does SPF 50 last longer than SPF 30?

No. Higher SPF provides more protection against the rays that cause sunburn, not a longer interval between applications. SPF 50 needs the same reapplication schedule as SPF 30. Keep that schedule on cloudy days too: up to 80% of the sun's harmful ultraviolet rays can pass through clouds.45

What if your moisturizer or makeup contains SPF?

Moisturizer and makeup with SPF still need reapplication approximately every two hours outdoors. In the US, cosmetics and moisturizers claiming SPF protection are regulated as sunscreen products, so the makeup counter does not create a regulatory escape hatch.34

Sunscreen comes in creams, lotions, gels, sticks and sprays, so choosing a format can resemble ordering from a menu with no food. Follow the directions for your chosen format. Never spray sunscreen directly onto your face; spray application needs particular care to achieve even coverage.45

What else matters during a day outside?

Reapplication is only one part of sun protection. Use shade, clothing, a wide brimmed hat and sunglasses as well. Seek shade when your shadow is shorter than you. Do not use sunscreen as a reason to spend longer in the sun.12

Keep the sunscreen bottle in the shade or wrapped in a towel rather than leaving it in direct sun. Replace expired sunscreen. If a US sunscreen has no expiration date, discard it three years after purchase, or discard it if you do not know its age.5

For children older than six months, follow the sunscreen label. Keep younger babies out of direct sunlight and ask a doctor before applying sunscreen. If sunburn leaves you feeling unwell or causes severe swelling or blisters, seek medical help.25