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How often should you reapply sunscreen?
Every two hours outdoors and right after swimming or sweating. Here is the rest of what dermatologists recommend.
Short answer: every two hours while you are outdoors, and right away after swimming or sweating. That is the American Academy of Dermatology's guidance, and it holds even for water-resistant and high-SPF sunscreens.
The basics
| Question | AAD guidance |
|---|---|
| Which sunscreen? | Broad spectrum (UVA and UVB), SPF 30 or higher, water resistant. |
| When to put it on? | Before you go outside; it takes about 15 minutes to start protecting. |
| How much? | About 1 ounce, roughly a shot glass, for an adult's exposed skin. Most people use too little. |
| How often? | Every 2 hours outdoors. |
| After water or sweat? | Reapply immediately after swimming or sweating. |
Why reapplying matters
Sunscreen rubs off on clothes and towels, washes off with sweat and water, and wears off over time in the sun. A high SPF number does not make one morning application last all day.
Days people forget
- Cloudy days. UV passes through clouds; the EPA advises sunscreen at moderate UV and above even when it is cloudy.
- Driving and sitting by windows. Long drives with the sun on one side of the face add up.
- Near water, sand or snow. These surfaces reflect UV back at you.
- Short errands that turn into hours.
Make it a habit
- Keep a small sunscreen in your bag or car.
- Pair it with something you already do: lunch, a coffee break, getting out of the pool.
- Check the UV index in the morning (see UV index explained) and set a reminder for high-UV days.
- Add shade, a wide-brimmed hat and sunglasses: sunscreen is one layer of protection, not the only one.
General sun-care information, not medical advice. If you have a skin condition, a reaction to a product or a changing mole, talk to a dermatologist.
Let your phone remember for youPars Skin shows today’s UV for your city, logs your sunscreen and reminds you to reapply, staying quiet when UV is low. It also flags sun-sensitizing ingredients like retinol in your products. Private on your iPhone; not medical advice.
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