When should you reapply sooner?
| Situation | When to reapply |
|---|---|
| You are outdoors without swimming or sweating. | Reapply every two hours. |
| You have been swimming or sweating. | Reapply immediately afterwards, following the bottle's directions. |
| You have dried yourself with a towel. | Reapply straight away. |
| Sunscreen has rubbed off. | Reapply to restore coverage. |
Cloudy weather and winter do not cancel the outdoor schedule. Your skin is exposed to harmful ultraviolet rays whenever you go outside, including on an overcast day. Reapplication matters on an ordinary walk as well as on holiday.1
What do 40 and 80 minutes mean?
A US sunscreen's water resistance label states whether it maintains its labeled SPF protection for 40 or 80 minutes while swimming or sweating. Those minutes describe protection in water or sweat, not a replacement for the regular outdoor reapplication schedule. Follow the product's specific directions for swimming and sweating. A water resistance label is a limited claim, even when the bottle has the confidence of beach equipment. No sunscreen is waterproof, and water resistant sunscreen still needs reapplication.34
How to apply enough sunscreen
- 1Choose a water resistant sunscreen with SPF 30 or higher and broad spectrum protection, which covers both UVA and UVB rays.
- 2Apply sunscreen to dry skin 15 minutes before going outdoors.
- 3Use enough to cover all uncovered skin. Most adults need at least about one ounce, roughly a shot glass, depending on body size and how much skin is exposed.
- 4For the face, use at least one teaspoon, about the amount covering the length of your index and middle fingers. Rub sunscreen thoroughly into the skin.
- 5Cover the neck, ears, tops of the feet and any exposed scalp. Use a lip balm with SPF 30 or higher for the lips.
- 6Repeat the application generously when reapplication is due, including after water, sweat or towel drying.
For a prolonged outing with a risk of burning, UK advice adds an initial application 30 minutes before leaving and another just before leaving. Applying sunscreen too thinly reduces protection, so frequent tiny top ups are not a substitute for generous coverage.2
Does a higher SPF last longer?
No. Higher SPF sunscreens last the same amount of time as lower SPF sunscreens. SPF 50 does not let you extend the interval between applications or spend additional time outdoors without reapplying. Chemical, mineral and hybrid sunscreens all need regular reapplication.35
Does SPF in moisturizer or makeup change the schedule?
An SPF moisturizer is still a sunscreen product, even if the front of the bottle would rather discuss moisturizing. Cosmetics and moisturizers labeled with SPF are subject to US sunscreen regulations. Their convenience does not remove the need to reapply sunscreen approximately every two hours outdoors.45
What about indoors or beside a window?
The two hour schedule applies to outdoor exposure; there is no single indoor interval to use for every situation. Window glass blocks UVB rays, which primarily cause sunburn, but UVA rays can pass through glass and contribute to premature skin aging.5
When does sunscreen need extra backup?
No sunscreen completely blocks ultraviolet radiation. Use shade, protective clothing and sunglasses alongside sunscreen. If you take medication, ask your healthcare professional about sun precautions because some medicines increase sun sensitivity. Consult a healthcare professional before applying sunscreen to a baby younger than six months.3
