What changes when you wear sunscreen?
| What matters | Wearing sunscreen correctly | Leaving exposed skin unprotected |
|---|---|---|
| Sunburn | Reduces the UV radiation reaching skin. | Leaves skin exposed to UV radiation that causes burns. |
| Wrinkles and age spots | Broad spectrum protection helps prevent premature aging from sun exposure. | Unprotected UV exposure contributes to premature aging. |
| Skin cancer | Helps reduce risk when combined with other sun protection. | Excessive UV exposure damages skin cells and increases risk. |
| Limits | Does not block all UV radiation or replace clothing and shade. | Skipping sunscreen does not remove the need for other protection. |
Sunscreen and protective clothing belong in the same plan, rather than competing for employee of the month. Cover skin with tightly woven clothing, wear a hat that shades the face, ears and neck, and use sunglasses with UV protection. Even in shade, use sunscreen on uncovered skin.25
Do you need sunscreen on cloudy days or in winter?
Cloudy or cool weather does not mean UV exposure has stopped. Check the local UV index: at 3 or higher, protect your skin. Water, sand and snow reflect UV radiation, so take extra care around them. UVA, which contributes to skin aging, can also pass through window glass. Winter exposure can be much lower far from the equator, so sunscreen is not necessarily needed year round in every location; local UV levels and exposure matter more than the season's name.123
How to get the protection on the label
SPF mainly measures protection against UVB, the main cause of sunburn. Broad spectrum adds UVA protection, so the large number is not the label's entire job description. Choose SPF 30 or higher with water resistance; SPF 50 or higher offers greater protection, but still needs regular reapplication.134
- 1Apply sunscreen to dry skin 15 minutes before going outdoors. Follow the product's directions.
- 2Cover all exposed skin generously. Most adults need about one ounce for uncovered body skin. Do not miss ears, neck, hands, feet or exposed scalp; use SPF lip balm on lips.
- 3Reapply at least every two hours outdoors, and after swimming, sweating or towel drying. Water resistant does not mean waterproof.
- 4Check the expiry date. Discard expired sunscreen; if there is no expiry date, replace it three years after purchase. Keep the container away from excessive heat and direct sun.
Who needs extra care?
All skin tones can develop skin cancer. Darker skin burns less readily, but a tan is not protection against sun damage. Take extra care if you burn easily, have many moles, have a family history of skin cancer or spend long periods outdoors. Retinoids and topical alpha hydroxy acids can increase sunburn risk. For sensitive skin, mineral sunscreens containing zinc oxide or titanium dioxide are an option. Keep babies under six months out of direct sunlight and ask a doctor before applying sunscreen.1467
Does sunscreen cause vitamin D deficiency?
Real life recreational sunscreen use has not been shown to cause vitamin D deficiency in trials. Oral vitamin D supplements are available if deficiency is a concern; leaving skin unprotected is not necessary to address it.3
What if you have already burned?
Sunburn redness can take 2 to 6 hours to appear and peaks at 12 to 24 hours, so feeling fine immediately after exposure is not a reliable check. Protect burned skin from further sun, use cool compresses or a cool bath, and do not pop intact blisters. Seek medical help for blistering, marked swelling or feeling unwell. Report a new growth or a mole that changes size, shape or colour to your doctor promptly.67
Where this answer comes from
- 1Sunscreen FAQsaad.org
- 2Sun Safety Facts | Skin Cancercdc.gov
- 3Sun Protectiondermnetnz.org
- 4Sunscreen: How to Help Protect Your Skin from the Sunfda.gov
- 5Shade, clothing, and sunscreenaad.org
- 6Sunscreen and sun safetynhs.uk
- 7Sunburndermnetnz.org
