How often should you reapply sunscreen, even over makeup?

Every 2 hours is the number to remember whenever you’re outside, and sooner if you’re swimming or sweating. That’s the FDA’s advice, and the NHS adds straight after toweling off or anything else that rubs it away. A higher SPF doesn’t buy you more time, either. The FDA notes that SPF isn’t directly tied to how long you can stay in the sun, so SPF 50 goes on the same clock as SPF 30.

Why do you need to reapply sunscreen?

Three things happen to your morning layer. It rubs off on your hands, collar, bag strap and phone. It washes off with sweat and water. And for most people it was thin to begin with. When dermatology researchers Petersen and Wulf reviewed the research on how people really use sunscreen, typical layers came to somewhere between a fifth and a half of what SPF tests use.

That same review has the most useful reapplying tip almost nobody mentions. Put sunscreen on before you go out, then add a second coat within the first hour. The authors found that early reapplication partly makes up for a thin first layer, and a second pass also catches the spots you missed the first time.

Do you need to reapply sunscreen indoors?

Mostly, no. In a 2019 trial, 20 indoor workers in Thailand put a full test dose (1 gram, or 2 mg per cm²) on their faces at 8 a.m., mixed with a dye that shows up under UV light, and spent less than an hour outdoors all day. About 16% had worn off by 10 a.m., very little after that, and 28% in total by 4 p.m. The researchers concluded that indoor workers who apply enough in the morning may not need to reapply.

Two big caveats. They started with the full dose, which most of us don’t, and the study didn’t look at people sitting in direct sun by a window. So for a desk day: no 2-hour alarm, but top up before a lunchtime walk or the trip home if the UV is still 3 or more, and treat a seat in direct sun through the glass like being outside.

How long does water-resistant sunscreen last?

On US labels, water resistant has a precise meaning. The product has been tested and must say whether it stays effective for 40 or 80 minutes of swimming or sweating, and the FDA is clear there’s no such thing as waterproof sunscreen. The NHS adds the part people skip: even a water-resistant sunscreen needs reapplying straight after you come out of the water, and again after toweling off, because rubbing takes it with it.

How do you reapply sunscreen over makeup?

Over makeup, the goal is a real amount of sunscreen without wiping your face off. Blot oil and sweat with a tissue first, then choose your format, knowing they’re far from equal. Lab Muffin author Michelle Wong sums up why: protection scales with how much you put on, and some formats put on very little.

How often should you reapply sunscreen at the beach?

Pack more than you think, since a full-body coat takes far more than most people squeeze out. Out for the day? Nubia’s Outdoor SPF reminders count the 2 hours for you and nudge you when it’s time to top up.

How often should kids reapply sunscreen?

On the same clock as adults: every 2 hours outside and after every swim or towel, which in a kiddie pool can mean a lot of pit stops. Babies under 6 months are different. The FDA doesn’t recommend sunscreen for them at all and says the best protection is keeping them out of the sun, especially between 10 a.m. and 2 p.m.

Safety note: Spray sunscreens can be flammable, so check the label and keep them away from grills, candles and cigarettes, and never spray one straight at your face.