Sunscreen is part of sun protection, which is a less convenient answer than buying one bottle. Use shade and protective clothing too, rather than treating sunscreen as permission to stay in the sun longer.2
When do you need to use sunscreen?
Apply sunscreen before going outside, including on cloudy or cool days and in winter. Check the UV index in your weather app: a value of 3 or higher means you should protect your skin from excess sun exposure. Temperature alone does not tell you how strong the UV rays are.3
Take extra care around snow, water and sand, which reflect UV rays. Higher elevations and places closer to the equator also increase exposure. Both occasional intense exposure, such as a beach holiday, and repeated exposure over time can damage skin. Sunburn can take several hours to a day to become uncomfortable, so feeling fine is not a useful signal to wait for.4
UVA rays, which contribute to wrinkles and age spots, can pass through window glass. UVB rays, the main cause of sunburn, are blocked by glass. If you spend time in sunlight through a window, avoiding sunburn does not mean you have avoided all UV exposure.1
What should you look for on the bottle?
Look for three things: broad spectrum protection against both UVA and UVB, SPF 30 or higher, and water resistance. SPF primarily describes UVB protection, so the number alone is not enough. On UK labels, look for at least four stars for UVA protection; a UVA symbol inside a circle indicates the EU standard. For sensitive skin, mineral sunscreens containing zinc oxide, titanium dioxide or both are a recommended option.125
How do you apply sunscreen properly?
- 1Apply to dry skin before going outdoors. General directions are 15 minutes before exposure; for a longer outing with a risk of burning, NHS advice is to apply 30 minutes before leaving and again just before leaving.
- 2Cover all exposed skin generously. Most adults need about one ounce for exposed body skin; use at least one teaspoon for the face.
- 3Include your ears, neck, hands, tops of feet, hairline and exposed scalp. Use SPF lip balm on your lips, and avoid getting sunscreen in your eyes or mouth.
- 4Reapply about every two hours outdoors and after swimming, sweating or towel drying. Follow the bottle's directions: water resistant does not mean waterproof.
What else protects you?
Wear tightly woven clothing that covers as much skin as practical, and look for a UPF rating on the label. Dry clothing protects better than wet clothing. A hat with a brim all the way around covers more than a baseball cap, whose job description stops rather abruptly. Choose sunglasses labeled for UV protection. Keep using sunscreen on uncovered skin even in shade.36
Who needs extra care?
Some medicines, including doxycycline and retinoids, increase sensitivity to sunlight. Lupus and medicines that suppress the immune system also call for extra sun protection. For babies younger than six months, prioritize shade and protective clothing, and ask a doctor before using sunscreen.145
If you get sunburned, stay out of the sun until redness has gone. Seek medical help if you feel unwell or your skin swells badly or blisters. Report a new mole, growth or lump, or a patch that changes size, shape or color, to your doctor promptly.2
