Do You Really Have To Put On Sunscreen 20 Minutes Prior To Being In The Sun?

I’m going to say that it really depends on what you’re doing after, and explain why.

Let me first start with this. If you hold that I must put on my sunscreen 20 minutes prior to exposure, please back up your opinion with facts. Otherwise, your opinion remains opinion. It is like preferring chocolate ice cream over vanilla. Your preference does not override mine.

Why is this an issue?

I’m a busy man. I’m also autistic. Furthermore, I have chemo brain. There’s no way I’m going to be sitting in my apartment and go:

I need to be out in 20 minutes. Time to put on the sunscreen.

Does it happen that I put it 20 minutes before being in the sun? Yes, it can happen, but it does not happen with any regularity. Most of the time, I want to go on a walk and I put the sunscreen on just before leaving the house. Same thing when I go out driving. So I see this requirement as eminently impractical.

So I went to Google to research it. I had to wade through a ton of myths, and opinions. I finally landed on a page that seemed to be not too bad:

Do You Really Need To Apply Sunscreen 20 Minutes Before Sun Exposure?

Yes, I’ve followed the links, but I’ve not seen anything supporting the author’s thesis in those links. The thesis is this:

It’s not just a matter of applying the same amount on every area. You need to give it time to dry and form a uniform film on your skin.

You can do the footwork yourself, and follow all the references, but make sure that you don’t just land on a page stating the same opinion. I don’t want opinions. You can call my argument here mere opinion, but if you counter my opinion with yours, we’re no better than where we started.

One page stood out of the pack, this one:

“Physical” vs. “chemical” sunscreens and other sunscreen myths

The author of this page does a lot of debunking. The bit that appears to support the position that you need to let the sunscreen sit 20 minutes before exposure is this one:

Both inorganic and organic sunscreens will provide UV protection as soon as they’re placed on the skin. The reason why a wait time is part of the application instructions is to allow the sunscreen formula time to dry and form a film on the skin. This makes it harder for it to be wiped off and it also means it can dry to as even of a film on the skin as possible.

The more evenly distributed the sunscreen is on the skin, the more even the coverage and the greater the average protection. If we take 10 umbrellas and hold them over one person, that one person may remain very dry during a downpour but everyone else will get soaked – if we distribute the umbrellas evenly more people will remain dry. Photoprotection works the same way, it’s measured as an average – you don’t want some areas of the skin with more sunscreen and greater coverage at the expense of other areas with less sunscreen and less coverage.

Listen, the guy is generally reasonable, so I don’t see any reason to doubt that what he is saying here is the truth. However, even if this is true. I’m not convinced that, as a general rule, you should put on the sunscreen twenty minutes prior to exposure. Let’s go over the two concerns in turn: if you don’t let it dry, it might wipe off, and it won’t be even.

The wiping off issue might be very real. However, if you are concerned about wiping it off, what are you going to do during those 20 minutes? Stand in the middle of the living room, not moving, with your arms flared??? Nobody is going to do this. We’re all going to sit down on the couch or somewhere else and, yes, the damn thing is going to be wiped off. I’m sorry, but I live in the real world and not in some sort of rarefied lab condition.

What about the problem of evenness. Well… I don’t know about you, but I am generous with my application. I use cream and I rub and rub. Now, I suppose it is possible to apply it carelessly, and maybe the vast majority of the population does, but not me. I’m sure that my application becomes more even as it dries, but does not matter? I don’t think so.

So is the 20-minute wait important or not?

In my view, it really depends on what you are doing after application. If I’m at the beach and preparing to go to the actual literal beach, I’m probably going to wait 20 minutes. The same is true if I expect to be in the water after application. Still more of the same if I go out running, and I expect to be sweaty like hell. Especially if swimming or sweating, I can see the rubbing off problem being a real issue.

However, when I just go out for a walk, or for a drive, there’s no point in waiting 20 minutes, or even worse, not applying the sunscreen. Because that’s what you end up with. If it takes 20 minutes, and I’m going on a 10-minute walk, why apply it in the first place?

In my view, the 20-minute wait is a worst-case scenario. If you’re not careful applying it, and if you are going to do something that is likely to take the sunscreen off of your body, wait. Otherwise, don’t.

Use your brain!