Is It Really Necessary To Reapply Sunscreen Every 2 Or 3 Hours?

by Gio
Do you really need to reapply sunscreen every couple of hours?

I have a dream.

I dream of one day when women (and men) will be able to slather on sunscreen in the morning and go through their day without the need to top it up.

No more stopping what you’re doing every two hours to apply another layer. No more wondering how the heck to do that without ruining your makeup. No more choosing between wearing sunscreen or getting wrinkles.

One day that dream will come true. That day is not today. Today, you still need to touch up your sunscreen every few hours. *sighs*

Here’s why:

Why You Need To Reapply Sunscreen Every Few Hours

Think of sunscreen like your laptop battery.

Your battery keeps your laptop working so you can work, play and chat with your friends. But, little by little, its energy fades away. After a few hours, you have to plug your laptop in to recharge your battery and give it new life.

Your sunscreen’s like that, too. When you first put it on, it keeps you safe from UV rays. As soon as those warm rascals hit your face, UV filters turn them into a less damaging form of energy (heat), so they won’t wreak their usual havoc (you know, wrinkles, dark spots, cancer).

But, in doing so, they’re getting used down. Sunlight slowly but surely breaks down UV filters, making your sunscreen utterly and completely useless overtime.

If you swim, play sports or sweat a lot, your sunscreen will disappear even faster. Water, sweat and even rubbing make sunscreen slide off your skin pretty quickly, leaving you unprotected.

Shop My Fave Sunscreens

How Quickly Does Sunscreen Break Down?

Here’s where it gets tricky.

Now, if you go for a swim or play a game of beach volley, it’s a given you need to reapply sunscreen immediately afterwards. All that sweat and exercise got a big dollop of sunscreen off your body and you need to top it up pronto.

But, what if you’re simply lying on the beach reading a good book? Or aren’t at the beach at all? Maybe you’re spending your day at the office and going out just for a brief errand. Do you need to reapply in that case?

As a general rule, the longer you stay in the sun and the strongest UV rays are, the quicker your sunscreen will break down and become useless.

The longer you stay in the sun and the strongest UV rays are, the quicker sunscreen breaks down Click to Tweet

Let’s say that you’re sunbathing at the beach. It’s 10 am and UV rays are pretty strong. You need to top up every couple of hours. No exception. Fail to do so and your sunburn will remind you.

If it’s a beautiful sunny day and you’re enjoying a picnic or a walk in the park with your friends, I’d still top up every couple of hours. UV rays are strong and you’re spending a lot of time outside, so better be safe than sorry.

If you’re spending most of your day indoors, away from windows, and venturing outside only to grab a quick coffee, your sunscreen will last a lot longer. UV rays won’t get much contact with it, so you may get away with topping it up only once a day.

If you’re indoors but close to a window, it’s another matter entirely. Glass blocks UVB rays, but UVA rays (the kind that causes wrinkles, dark spots and cancer) can still get through. Top your sunscreen up regularly. Every couple of hours as a rule, but if it’s a gloomy, cloudy day when UV rays are weaker, every 3 hours or so may be ok.

Related: Is Sun Exposure Through Glass Dangerous?

The Bottom Line

There are times when you can get away with topping up your sunscreen less often. But, if you want to stay on the safe side, put it on every two hours.

Do you reapply sunscreen throughout the day? Share your experience and tips in the comments below.

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15 comments

La Bisbetica March 8, 2011 - 5:09 pm

Thanks for sharing this tips, they are very useful! I spend most of my time indoor and I often wear makeup, I’m happy to know I don’t have to reapply sunscreen.

Reply
beautifulwithbrains March 8, 2011 - 9:01 pm

La Bisbetica, you’re welcome. I’m glad you find them useful. 🙂

Reply
bagaela March 8, 2011 - 10:54 pm

A very good question again, that comes with a very good answer 🙂
I’m kind of sunscreen-obsessed, which is not suprising, as I tend to have allergies caused by the sun…it’s strange tough, becsause I have beige-olive toned skin, that tans easily.
I use pretty much the same method as You wrote – I don’t reapply my sunscreen during day (only with my spf powder, but in a normal day, it’s for the anti-shine effect) and I frequently reapply it when I’m on the beach or during a very hot, sunny day (like when I spend my holiday somewhere hot and sunny and walking in the city all day long)
But lately I’ve been using some mineral sunscrens (like Bioderma’s mineral spf 50 or Avene’s mineral or some japanese brands) and I only use some powder on the top, or use a chemical with less spf and with a foundation with spf and powder with spf.
I’m thinking about no puchasing a pure chemical sunsreen any more, as there are fabulous minerals out there (especial oney from japan, theh you can get from sasa.com for example) and the mineral screen don’t oxidize like chemical.
The sunscreen that my foundation contains is just enough cemical.

Reply
beautifulwithbrains March 9, 2011 - 11:25 am

Bagaela, thanks. I’m sunscreen-obsessed like you as I think it is so important to protect our skin from the sun but at the same time, there’s no need to be paranoid about it and reapply it too often if it is not necessary like when you’re not spending time outdoors.

I had never tried mineral sunscreens but you are tempting me too. They sound wonderful. I hope they will soon become more easily available everywhere.

Reply
Jeni March 9, 2011 - 2:07 am

I normally wear sunscreen that has Zinc Oxide in it, which doesn’t break down in the sun. But I still reapply every two hours if I’m out at the pool or beach. I wear sunscreen every day under my makeup, but I still get paranoid I don’t have enough protection! Recently I bought a powder foundation with SPF 50 that I’m going to wear this summer over my regular sunscreen and makeup – here in Las Vegas you need as much protection as you can get.

Reply
beautifulwithbrains March 9, 2011 - 11:28 am

Jeni, I love sunscreens with Zinc Oxide too and I think if one spends a lot of time in the sun, it’s still important to reapply it. Even if it doesn’t break down in the sun, it may always slide off your face if you sweat so I’d rather be cautious. 🙂 But I think what you are doing is enough to protect your skin from UV rays. 🙂

Reply
Makeup Morsels March 9, 2011 - 3:53 am

Awesome! b/c I don’t generally apply sunscreen throughout the day. If I go swimming/to the beach/running, I’ll reapply it though.

Reply
beautifulwithbrains March 9, 2011 - 11:29 am

Makeup Morsels, lol. Yes, there is no need to reapply it unless you spend a lot of time outdoors and sweat or swim. 🙂

Reply
xin March 9, 2011 - 3:55 am

i usually stay indoor so one application in the morning is sufficient for me already 🙂

Reply
beautifulwithbrains March 9, 2011 - 11:29 am

Xin, that’s what I do too. I think it’s great that you don’t have to reapply sunscreen if you stay indoors. 🙂

Reply
LatestGirls March 11, 2011 - 7:47 am

I am just out for some mins I guess when traveling from home to the office.

When I return home its about sunset. So I guess it would be just 1 time for me.

Reply
beautifulwithbrains March 11, 2011 - 12:52 pm

LatestGirl, yes, one application would be enough in that case. 🙂

Reply
READING RECOMMENDATIONS FOR THE WEEKEND 35 | March 11, 2011 - 9:44 am

[…] Is It Really Necessary To Reapply Sunscreen Every 2 Or 3 Hours? by Beautiful with Brains http://beautifulwithbrains.com/2011/03/08/is-it-really-necessary-to-reapply-sunscreen-every-2-or-3-h… […]

Reply
Rebecca Reilly November 28, 2017 - 7:50 pm

I usually don’t reapply. I go to work at 2pm , and live in the mountains. By 4pm , the sun is setting.
But are UVA rays present in twilight / sundown ?
After reading this , I will reapply.
Thank you.

Reply
Gio December 3, 2017 - 7:22 pm

Rebecca, yes, as long as the sun hasn’t fully set, some UV rays are still around so it’s best to reapply sunscreen.

Reply

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