Centella Water Fit Sun Serum: how to use it

What should you check on the tube?

Look for separate information about SPF and UVA protection. SPF mainly describes protection against UVB, the ultraviolet rays responsible for sunburn. Broad spectrum means protection against both UVA and UVB. A sunscreen's useful details are its protection ratings and directions, which are less poetic than "Water Fit" but considerably more useful. SPF is not a calculation of how many extra hours you can spend in the sun.3

Protection labels differ between countries, so use the label on the version you are buying. On UK sunscreens, look for at least SPF 30 and at least 4 star UVA protection; a circled "UVA" indicates that the sunscreen meets the EU standard. UK labels can use stars or a circled "UVA" to describe UVA protection, giving the packaging a small astronomy department.23

How do you apply it?

1. 1Apply sunscreen before going outdoors. General sunscreen guidance is to apply it about 15 minutes before sun exposure; follow any specific timing on your tube.
2. 2Use enough for full coverage. General guidance for the face is at least 1 teaspoon, approximately the amount covering the length of your index and middle fingers. Rub it thoroughly into the skin.
3. 3Cover all exposed skin, including your ears and neck. For wider body coverage, most adults need at least 1 ounce of sunscreen, with more needed depending on body size.
4. 4Reapply every two hours while outdoors, and immediately after swimming or sweating. Reapply after towel drying or when sunscreen has rubbed off.

Applying sunscreen too thinly reduces its protection. If you expect prolonged sun exposure that could cause burning, UK guidance is to apply sunscreen 30 minutes before going out and again just before leaving.2

Can you use it for swimming or exercise?

Choose a sunscreen explicitly labelled water resistant if you expect to swim or sweat. "Water Fit" is not a substitute for that label. No sunscreen is waterproof, and all sunscreens eventually wash off. US water resistant labels specify whether protection lasts for 40 or 80 minutes during swimming or sweating; follow the reapplication directions on the actual product.23

What should you expect from sunscreen?

Sunscreen protects against ultraviolet exposure rather than working toward a visible result after several weeks. UVA and UVB contribute to skin ageing and skin cancer, while UVB is the main cause of sunburn. SPF 30 offers high protection and SPF 50 offers very high protection when applied in sufficient amounts. Sunscreen and protective clothing do not block all ultraviolet radiation, so shade remains part of the plan.4

Wear sunscreen when going outdoors, including on cloudy days and during winter. A short walk still counts as outdoor exposure. Use a hat and clothing alongside sunscreen; a wide brim protects areas that a baseball cap leaves exposed, including the ears and sides of the face.15

What if your skin is sensitive?

If your skin is sensitive to chemicals in sunscreen, a mineral sunscreen containing zinc oxide or titanium dioxide is an alternative. Do not choose a sunscreen for sensitive skin from its name alone. For babies younger than six months, speak to a doctor before using sunscreen and keep them out of direct sunlight.25

How should you store it?

Keep sunscreen away from excessive heat and direct sun. Outside, keep the container in the shade or wrap it in a towel. Follow its expiry and storage instructions, and discard sunscreen that has passed its expiry date.3

When does sunburn need medical attention?

If you become sunburned, get out of the sun and go indoors. Do not pop blisters. Seek medical care for very large blisters; if blistering comes with feeling unwell or heat exhaustion, seek emergency care.6