How to choose which SPF to use

Should you choose SPF 30 or SPF 50?

SPF means sun protection factor and mainly measures protection against UVB, the rays primarily responsible for sunburn. SPF 30 meets the recommended minimum; SPF 50 or 50+ is a reasonable choice if you want greater protection. Neither blocks every UV ray.45

Those percentages depend on applying enough sunscreen. A thin layer reduces protection. SPF is not a timer: SPF 50 does not give you 50 hours outside, and a higher number does not extend the interval between applications.247

What else should the label say?

UVA contributes to early skin aging as well as skin cancer. On UK sunscreens, look for at least four stars for UVA protection; UVA inside a circle indicates that the sunscreen meets the EU standard.347

Water resistance matters particularly for swimming or sweating. The label states whether protection lasts 40 or 80 minutes in those conditions. No sunscreen is waterproof. Reapply after swimming, towel drying or sweating, following the bottle's directions.457

Which formula suits your skin?

Pick a format you will use repeatedly, rather than one you admire while leaving it in the cupboard. Keep the same protection requirements whatever texture you prefer.2

• Creams suit dry skin and facial application.
• Gels suit oily skin and hairy areas.
• Sticks are useful around the eyes.
• For sensitive skin, consider a mineral sunscreen containing zinc oxide, titanium dioxide or both.
• For dark spots, consider a tinted SPF 30 or higher sunscreen. Iron oxide helps protect against visible light, which can worsen pigmentation, particularly in darker skin tones.

Mineral and chemical sunscreens both protect mainly by absorbing UV radiation. Choose by the finished product's protection ratings rather than assuming the filter category determines its SPF.26

With sprays, getting enough even coverage is harder to judge. Spray until skin glistens, then rub it in. Never spray directly onto the face, avoid inhaling the spray, and keep it away from heat and flames.2

How to get the protection on the label

1. 1Check the expiry date. For a US sunscreen without a printed date, discard it three years after purchase, or if you do not know its age.
2. 2Apply before going outside, following the label. General US directions say 15 minutes beforehand; NHS advice for exposure long enough to risk burning is 30 minutes before leaving and again just before leaving.
3. 3Cover all exposed skin, including ears, neck, hands, feet and exposed scalp. Most adults need about one ounce to cover exposed skin; use at least one teaspoon for the face.
4. 4Reapply approximately every two hours outdoors, and after swimming or sweating. Replace sunscreen that has rubbed off or been removed by towel drying.

When do you need extra care?

Use sunscreen on uncovered skin when going outdoors, including cloudy days. A forecast UV index of three or higher is a clear prompt for daily protection. Add shade, covering clothing, a hat and sunglasses; sunscreen alone cannot fully protect you. Water, snow and high altitude call for extra care.235

People of every skin tone need sun protection. Take extra care if you burn easily or have a personal or family history of skin cancer. Some medicines increase sun sensitivity, so ask your clinician about precautions for your medication. Keep babies under six months out of direct sunlight and ask a doctor before using sunscreen on them.45