How does Benzoyl Peroxide fight acne?

If you've ever had acne, you've probably tried some creams or washes with "benzoyl peroxide" somewhere on the label. How is it that this specific ingredient is helpful for fighting acne? What is happening at the molecular level when we apply some benzoyl peroxide to our acne? Let's find out!

127 Benzoyl Peroxide

Melissa: [00:00:00] Hey, I'm Melissa.

Jam: I'm Jam

Melissa: and I'm a chemist

Jam: I'm not

Melissa: and welcome to chemistry for your life.

Jam: the podcast that helps you understand the chemistry of your everyday life.

Melissa: Okay.

So this episode is actually inspired by a few things. One, our previous skincare routine episodes

Jam: yes. Yes.

Melissa: Two, content from Dr. Shah he's the dermatologist that really got me excited about skincare in the first place

Jam: Nice.

Melissa: and then my own skincare routine and also your wife.

Jam: Okay. Nice.

Melissa: So this episode is all about how benzoyl peroxide works. It's magic.

Jam: Okay. I've definitely heard of that stuff. I have used it. I have had it. I've had tubes of it. I've had, yeah, that's probably the only like acne related sort of ingredient [00:01:00] that I actually can know.

And remember in my head.

Melissa: Yes. So it's a really good acne fighting ingredient. Actually. There's really high evidence that it does fight acne, scientifically speaking.

There's some other stuff we talked about, like hyaluronic acid that doesn't fight acne. It also doesn't cause acne it's basically just a moisturizer,

Jam: Right, right.

Melissa: but this actually fights acne.

Jam: Okay.

Melissa: Okay. So luckily I don't struggle with the acne a ton at this point in my life. I more have like, blackheads, but I don't have a ton of like those crazy big white heads. Um, but every once in a while, I'll get one usually related to eating sugar, which actually science does say that eating sugar can be related to breakouts. So when that happens, I learned a trick from your wife. That I have a little tube, benzoyl peroxide gel, and I'll put it on wherever the little acne white head has started. I [00:02:00] feel it starting. And then I wake up the next day and it's gone.

Jam: Wow.

Melissa: And she told me that, and I'm not sure I really believed her, but also you can get these tubes for like three to $5 of like benzoyl peroxide,

Jam: Yeah. Yeah,

Melissa: to not very expensive.

Jam: definitely.

Melissa: And they last a long time. You can also get benzoyl peroxide, a wash, like designed to put it on and then rinse off. So it was first suggested to me by your wife, Emiliee. It was further suggested by this dermatologist on Tik TOK. And I really wish I would have known about this as a teenager. So to any teens out there listening about how this works, please. Don't suffer like I did because I suffered, I definitely had acne as a teenager. But I don't as much anymore.

Jam: Nice.

Melissa: Okay. So before we talk about the chemistry of benzoyl peroxide, let's just talk about what acne is. There are different [00:03:00] types of acne that form. But the one we're talking about mostly is a white heads. That's kind of the main thing that benzoyl peroxide works on as far as I'm aware. And I guess it could work on other stuff, but we'll talk about it.

Essentially. Acne exists because you have follicles in your skin, hair follicles, and those excrete oil.

Jam: Uh, huh.

Melissa: And that oil is used to keep your skin from drying out and from taking in too much moisture, it basically protects us from losing or gaining too much water.

Jam: Okay. Got it.

Melissa: Totally makes sense. And occasionally those follicles can get blocked if there's too much oil produced and the too much oil for di produce can be caused by hormones or eating too much sugar or a few other things.

Jam: Okay.

Melissa: And then if they get blocked there's bacteria that always lives in your skin called P acnes. [00:04:00]

Jam: Okay.

Melissa: it starts to thrive off of the dead skin cells and the oil that are building up.

Jam: Okay.

Melissa: And then your body recognizes that something's wrong

Jam: Uh huh.

Melissa: and it sends blood to the area to drop off white blood cells.

Jam: Okay.

Melissa: So that they can rescue you from this extra bacteria.

Jam: Right, right.

Melissa: And the blood rushing to that area is why it gets red and inflamed.

Jam: Okay.

Melissa: And then the white blood cells that come and try to save you as they die. They're just in the blocked poor. So then that's where you get the Whitehead filled with dead white blood cells, dead skin cells and oil.

Jam: Uh, I see. Yeah.

Melissa: That's what's all in that pus there.


Jam: Huh?

Melissa: So that's what a white head is basically. And like I said, it can be caused by hormones, eating too much [00:05:00] sugar, but that's the main idea

Jam: Okay.

Melissa: now how benzoyl peroxide works is pretty exciting in chemistry.

Jam: Nice.

Melissa: So one thing that we've talked about a lot lately with coffee is solubility and different things have different solubility in different substances. really simple one you can think of is oil and water. Water is not good at interacting with oil. If you put oil in your pasta water, for example, the oil kind of stays in pockets.

Jam: Right.

Melissa: So, if you try to wash your face without something that can, you know, get at the oil, it's not really going to do anything Right,

That oil layer on our skin is a barrier.

Jam: Yeah.

Melissa: So something that's cool about benzoyl peroxide is it has non-polar groups on either side. It's called peroxide. Cause there's two oxygens. That's a functional group. Two oxygen's linked together. But on either side [00:06:00] of those functional groups, there are two benzene rings. We've talked about benzene before, but the big thing is those are two pretty big non-polar groups.

So if it's non-polar, that means the electrons are pretty evenly shared all the way through. So there's not any big areas of high electron density or low electron density.

Jam: right, right.

Melissa: So there's not big positives and big negatives. So the main intermolecular force that you're going to see from that is just dispersion forces.

Jam: Okay.

Melissa: So it's going to interact well with other things that don't have poles that doesn't have a positive and a negative portion and oil happens to also not have polls.

Jam: Right, right.

Melissa: And if you want more info on that, you can go way, way, way back to the episode we talked about like the first episode or second episode, I think we ever did maybe.

Jam: Uh, huh?

Melissa: On why get, how geckos walk on walls?

Jam: it was pretty early, but yeah.

Melissa: So benzoyl [00:07:00] peroxide works well because it. is soluble in the oils and fats that are hanging out in your acne in that little white head.

So if you zoom in and imagine that benzoyl peroxide is absorbed through the skin, because there's still a light layer of skin over the white head.

Jam: Uh, huh.

Melissa: And then it can just interact chemically with all those oils and it will evenly, or maybe not evenly, but easily get in through all these fats. Whereas other things maybe won't be able to penetrate the fats and oils as well, if they have more polarity to them.

Jam: Right.

Melissa: So that's the one thing it's soluble and oil and fat,

Jam: Okay.

Melissa: but then it has this functional group in the middle of the peroxide group is two oxygens together.

So. You've probably heard of that as hydrogen peroxide. That's a hydrogen oxygen oxygen, hydrogen H two O two. This is similar. It has the two oxygens [00:08:00] together. So peroxides tend to form radicals

Jam: Okay.

Melissa: and we've talked about radicals before.

They are a single electron. Do you remember what you said about them?

Jam: Um,

Melissa: We talked about it in the antioxidant episode.

Jam: I remember talking about them, but I don't remember what I said about them.

Melissa: You said their name matches their behavior

Jam: Okay.

Melissa: get in and mess stuff up.

Jam: Yeah, yeah, yeah.

Melissa: So

they're radical. Yeah. So radicals act radically. They get in there and they must stop. I think you said That maybe I said that, but I remember you talking about how their, it was pleasing that their name matched

Jam: Yes.

Melissa: in some way

Jam: Definitely stuck with me. So maybe no matter who said it, I still, I did remember that. That is what they are like, so,

Melissa: so,

in this case, they may produce some radicals just naturally by interacting with light, but also your body metabolizes them and produces, uh, radicals that way.

Jam: okay.[00:09:00]

Melissa: So that's oxygen radicals that it produces from the peroxide group and oxygen radicals.

Cause what's known as oxidative stress to bacteria, which the best way I can think about it is it puts too many radicals in the bacteria that it can't handle and kind of blows it up. The cell can't manage.

Jam: Interesting. Okay.

Melissa: So the oxidative stress kills cells.

Jam: So it's sort of, kind of like we're using radicals in this case in a good way.

Melissa: Yes.

Jam: Normally, we would not want to just add a lie radicals to our system, but because we're doing it in a very specific place for a specific reason, it's helpful.

Melissa: exactly.

Jam: Okay. Okay.

Melissa: So in this case, you harness the power of radicals, doing bad things to do something good for you.

Jam: Okay.

Melissa: And it's induced oxidative stress in bacteria. Specifically, the bad thing about radicals is they can induce [00:10:00] oxidative stress in other areas too. So you don't want them all over your cells or whatever,

Jam: Yeah.

Melissa: but in a bacteria you do want oxidative stress so that the bacteria dies.

Jam: Okay. Interesting.

Melissa: So I think of benzoyl peroxide as being able to penetrate the lines of the enemy, maybe like an undercover spy, it can get in amongst the oil. It can get in amongst the gunk release radicals that do damage in a controlled way. You know, you're only putting it on that one spot or only on your you're using your facial face wash.

You know,

Jam: Yeah.


Melissa: it kills the enemy. And your white head goes away?

Jam: Okay. That is very interesting.

Melissa: That's how I think of its function. It gets in there and then it releases the radicals.

Jam: Nice. Dang. That's cool.

Melissa: And here's, what's nice about it using the radical mechanism is because it causes oxidative stress instead of using some other way to be [00:11:00] antibacterial.

It actually, the bacteria is not going to be able to develop an immunity to that.

Jam: I

Melissa: So a lot of times bacteria figures out how antibiotics are working and then they figured out how to mutate to thwart that,

Jam: Right,

Melissa: I mean, they're not figuring it out. They're not sentient,

but you know,

Jam: It's yeah, they're adapting.

Melissa: yeah, they're adapting.

but you can't really adapt to avoid oxidative stress.

You have to have the Right, balance of stable oxygen and oxygen radicals. And if they have too many oxygen radicals, they can't function.


Jam: right.

Melissa: So there's no adapting, so we don't build up any kind of immunity. So you can use benzoyl peroxide forever and I'll keep working

Jam: Wow. That is great. I didn't even think about that. I mean, I've heard a lot about that. You know, bacteria adapting for my wife. Work, he or she has to prescribe antibiotics all the time, talk to people about their infections and help them figure that stuff out or whatever. So I know that side did not even think about how we're applying to our skin is also trying [00:12:00] to, you know, combat bacteria.

I just, you know, have, have those really in different categories in my mind, but it's so cool that it's doing it. Not in out like medicinal antibiotic way that can't be adapted to or whatever that, wow. I didn't even think about that.

Melissa: I know. I think it's really cool.

Jam: Yeah.

Melissa: So, and that's kind of a brief overview. I think if I was a biologist, I'd be able to go a lot more in detail into why oxidative stress occurs the way it does. And if you're a biologist listening and you want to come on and explain it to us, I'd love that. Feel free to do that.

But I think that this way of thinking of it, like it's just going to get in there and wreak havoc is a really good way of thinking about what radicals are going to.

Jam: Yeah, yeah, yeah.

Melissa: Okay.

So I want you to try to summarize the chemistry of that. There's the two parts, and then I'll give you one fun fact and one thing to look forward to really.

You don't have as much to look forward to as the [00:13:00] listeners, but one fun fact in one thing for our listeners to look forward to.

Jam: Okay. Okay. So I liked your analogy a lot. It helped me understand it very well. I think one thing I'll add in is basically, so we've got this pimple is Whitehead it's full of bacteria and dead white blood cells and, and dead skin cells, which the bacteria is loving, thriving there. And it's sort of basically like the enemy army, like.

So, while I was trying to thinking about is obviously each cell of bacteria and stuff made up of atoms and molecules and stuff. Like we are, we talk about all every episode, um, that's your world molecules and atoms.

Melissa: Yeah. That is the tiny world that I pretend to shrink myself down and go into a lot.

Jam: And, and so together they make up like a tank,

Melissa: Oh [00:14:00] yeah.

Jam: full of soldiers or whatever.

Melissa: Yes.

Jam: Benzoyl peroxide

and bacteria and fats and oils and stuff like that. That is non-polar. So even distribution of electrons, not like heavily concentrated on one end of the molecule or another even distribution. So we needs something. That's also even distribution of electrons. Non-polar to be able to interact with it.

Melissa: right.

Jam: The benzoyl peroxide, we apply it to our little whitehead it dissolves in, goes into our skin goes into the Whitehead. Each of those, those collection of atoms, those molecules are also a tank and they are cause they're non-polar as well. And they just go right in, look, it looks totally fine. They're a tank too.

Melissa: Oh, they look like the enemy tanks

Jam: At least in the way that like [00:15:00] matters in this scenario, you know?

Melissa: there. Non-polar enough to be able to go in undercover type of thing. Okay.

Jam: And so, but because they have that extra, so that's already the most important step or the first step is to just even get in there.

Melissa: To penetrate.

Jam: Yeah. Otherwise what can we even do if we can't get in there?

Melissa: Yes, exactly.

Jam: they get in there? Great thing to look a little like the enemy to just integrate into the enemies force.

Melissa: Yes.

Jam: the difference is that they have this little extra soldier in there. That's kind of a secret little weapon, which is that extra electron, the radical, the oxygen with one electron. Right. And so then what happens once they fully integrated? Obviously it's probably happens all at once or sort of, you know, who knows the actual steps with this, but for the sake of the analogy, once they've integrated, that radical gets out of the tank goes and gets in the bacteria's tank. And just because of that, [00:16:00] this is the harder part. Just messes it all

Melissa: This message just destroys the


Jam: Just goes in, say like, just press the self destruct or something

Melissa: Yeah. Or throws a hand grenade.

Jam: Yeah. It does a hand grenade, whatever this radical is radical and it's not taking any prisoners, it's just there to just completely disable the enemy.

Melissa: Yes.

Jam: And it does that very well.

Melissa: Yes. That's a really good analogy.

Jam: And so that once that happens overnight, we're asleep in this war is raging, absolutely raging carnage happening in this little white, um, hill of on our, on our, uh, let's a little big horn.

Melissa: it on as you went to


Jam: little battle, a little big horn is happening here. And then when we wake up the battle's over.

And all of the enemy tanks, ideally, hopefully have just been disabled completely.

Melissa: disabled.

Jam: And all the bacteria has fall apart. Denature, whatever you want to [00:17:00] say, I guess not denatured, but

Melissa: It's died through oxidative stress

Jam: killed. Yep. And then we have a clear face, hopefully.

Melissa: and normal levels of acne and oil are restored.

Jam: Nice.

Melissa: The other thing I forgot to, I wanted to say two things. One to clarify your analogy, the way the radicals is formed is the bond between the two oxygen's typically will break and each of the oxygen then gets one electron to go with it.

Jam: Got it. So they're probably like two radicals coming out of each tank.

Melissa: but it did say specifically that your body metabolizes it first.

So I think some. Some radicals are generated just by being exposed to light. That happens with all peroxides is they will, that bond will break into radicals will form. And some of it is generated through your body. Metabolizing it first. It wasn't super clear on the percentages. I read one paper that said like 98% and other [00:18:00] bureaus had 40% would be metabolized.

I'm assuming you're getting radicals from both mechanisms, but the main idea is the bond between the oxygen bonds will break. There's a bond between two oxygen atoms. It will breaking it. splits evenly. So each atom gets one electron.

Jam: Got it. Interesting.

Melissa: that's how that works. The other thing is the way I think of benzoyl peroxide is like a little gel that you apply on your face and then you just leave it. But there are washes and part of what makes the washes for benzoyl peroxide effective is not only can they get in that bacteria, but they can wash away oil

because they're in there breaking it up.

Jam: Nice.

Melissa: So that's also part of it too, is

Jam: can kind of be preventative a little bit too, because if there's any excess oil somewhere. Got it. Okay.

Melissa: Okay.

So that was really good. I liked that analogy a lot.

It was very dramatic. I could picture it in my mind. So that was really good. I really liked that it, oh, and it [00:19:00] also can break up the oil. That's blocked in there as a wash too, you

Jam: Nice.

Melissa: Yeah. It does lots of good

Jam: Yeah.


Melissa: So here's one fun fact. There is research in the dermatology sphere that shows that benzoyl peroxide can act.

What's known as synergistically with other acne products. So it's not like if you use benzoyl peroxide and product B, you get the justbenzoyl peroxides effect and product B effects actually product B can enhance the effectiveness of benzoyl peroxide.

Jam: Interesting.

Melissa: and I couldn't find a lot of research on why, but I thought that was so cool.

And it made me think how much dermatologists have to understand about how products work together, because some products can kind of cancel each other out and some products can like boost each other up the way that the doctor, it wasn't actually Dr. Shah, but his partner said is like a plus B doesn't equal C.

So [00:20:00] benzoyl peroxide plus something else doesn't equal. Just those two together. It equals like five times C.

Jam: Okay.


Melissa: Yeah.

So I thought that was really cool.

Jam: Yeah.

Melissa: So that's a fun fact about benzoyl peroxide and how smart dermatologists are. The second funding for our listeners to look forward to.

Jam: Uh huh.

Melissa: Is this episode is kind of based highly in the episode about antioxidants,

Jam: yeah. Yeah.

Melissa: where we talked all about how radicals form and how antioxidants work. And so we're actually going to play that in our rebroadcast next week. But also this episode is so much entrenched in bleach because benzoyl peroxide can easily bleach your sheets.

if I put this on my face, every bleach pillow that I use specifically, because I know it can tend to bleach things.

Jam: Yeah.

Melissa: So if you're interested in that, the next rebroadcast after that will be how bleach works.

Jam: Got it.

Melissa: So those are two fun episodes. You guys can look [00:21:00] forward to.

Jam: Yeah, I like both of those a lot. I kind of feel like I remember the antioxidants one a little bit better than the bleach one. So I'm interested to look back at those.

Melissa: And it just gives a lot more information about radicals and how they form, but then also how our bodies fight them.

Jam: Yeah. Yeah.

Melissa: So I think that will be a good one to pair with this.

Jam: Nice.

Melissa: So good job, Jam, I'm really impressed at how you came up with an analogy on that. This was a fun episode.

Jam: Well, I had a great start. So I'll have to do is add in some drama. You know what I mean?

Melissa: Yeah, you added in some good, some good, uh, dramatic points there. But is there anything about your week that you also had fun that you want to share with us.

Jam: Okay. So speaking of adding in drama and like intensity and all that kind of stuff, uh, to the analogy, my wife and I have been watching a show that is not new, that most people will think. How are you just now watching this show? We S we were looking for a show to watch [00:22:00] together, and we decided to try out watching, watching the show lost.

From like 2003/2004 on ABC. And I never watched it. We didn't have any of those channels, like in the ability to watch that, whenever that show came out when I was a kid. So I had no way to watch it.

I'd heard other people talking about it back then. Obviously it was a huge deal, but I never watched only hear people's opinions and forgot almost any spoilers they might've excellently given, you know, and.

Melissa: a clue what happens in that show?

Jam: Yeah. So we, we started watching it. We're just like, let's just see. And of course, just like everybody else back in, you know, 15, 18 years ago, we got sucked in because it's dramatic and there's lots of mysteries and stuff, but it's been fun.

And I, I think the thing I like about it is, you know, there's lots of new TV shows all the time. It's kinda cool to go watch an older one. It's not old obviously, but older and we get sucked into it.

Melissa: Yeah. That is fun.

Jam: And I had, I had read an article that didn't have any spoilers in it, but just talked about [00:23:00] how this person made a point that they felt like lost set up a lot of important stuff for TV in the later years

Melissa: Oh, interesting.

Jam: and helped sort of bring more of those kinds of higher budget niche, um, complex story type shows to the, to a broader audience.

Melissa: that people would still be interested, even though it was more complex.

Jam: Yeah. And they made a case that like, if it had premiered like 10 years later on Netflix, that it might have actually been more successful in some ways and not have had to fight so hard to even exist and stuff. So anyway, I'll have to say, uh, super behind just now watching lost. Um, and, but it's been really fun.

Melissa: That does sound really fun.

Well, similarly, I've been listening to a very old thing.

Jam: Uh, huh,

Melissa: It's a little book called little women, and there is a podcast called Phoebe reads a [00:24:00] mystery. And it's Phoebe judge who has a great calm, soothing voice. And she literally just reads a chapter of a book every day,

Jam: Oh, nice.

Melissa: but it's so hard to like wait for the next episode to come out because I'm all caught up.

So I'm every day I'm waiting to hear what happens next in the book. And it's caused me to slow down, but also to be really invested in a way that I don't know that I've been invested in a book or an audio book in a really long time. And so that's been really fun and it's really encouraging, and it sends a lot of really good messages.

So I really it's, you know, a book about reflecting on being content and trying to, you know, be quote unquote good and loving

Jam: Yeah.

Melissa: and kind, and how really, that usually works out better for you in the end.

Jam: Uh huh.

Melissa: And it's been really good. I really liked it. I know it's kind of outdated and there are some things about it that are problematic, but it's still.

Been a nice journey with Phoebe judge. So go check that

Jam: totally. [00:25:00] Yeah. I have not read that, but I've always heard good things about people. Who've read it and I have seen more recent film adaptation and loved it. So I'm definitely open to reading the book for sure. I feel like stories like that. Obviously there's things that are outdated, but it's cool that there can be a compelling story from a previous time.

That's probably pretty accurate to the time, you know?

Melissa: And it's also, I think. Something that I think Jane Austin does too. And so when I read Anna Karenina had this thing that I was amazed that even not long ago, there are things about human nature that are the same.

Jam: Yes, you're right.

Melissa: And I feel like little women is good at addressing some of those things. That are the same, same tendencies that I have.

There's a chapter on the beginning of marriage that I was like, whew, if this isn't just the most accurate. So I think that's also really encouraging as some things about humans and discontentedness and needing to grow past our demons, you know, it was really, really encouraging.

Jam: that's awesome.

Melissa: So That's been [00:26:00] fun.

Jam: Yeah, that's definitely cooler and more inspiring than lost. So,

Melissa: It's made it hard to go listen to the murder podcasts I listen to after, I've just been listening something so uplifting and inspiring. And now I'm like, what is this? What am I doing?

Jam: Well then there's another reason that I'm very glad that you're listening to that. So,

Melissa: That's funny. All right. Well, thanks Jam for coming and learning about benzoyl peroxide. I was really excited to share about this because I was wondering how the magic of the overnight disappearing zit occurs.

Jam: definitely and thank you for teaching me. I haven't really wondered how benzoyl peroxide has worked. I've just used it. And so this is a much cooler explanation than I thought it was going to be. So anyway, thank you for teaching us. And if you have questions or ideas out there, you listener who wonder about something in your life that could be chemistry.

Please reach out to us on Gmail, Twitter, Instagram, or Facebook at chemforyourlife that's chem F-O-R your life to [00:27:00] share your thoughts and ideas with us. If you'd like to help us keep our show going and contribute to cover the cost of making it go to, or click the link in our show notes to donate the cost of a cup of coffee.

If you're not able to donate, you can still help us by subscribing on your favorite podcast app or rating and writing a review on apple podcasts. That also helps us to share chemistry with even more people.

Melissa: This episode of chemistry for your life was created by Melissa Collini and Jam Robinson references for this episode can be found in our show notes or on our website. Jam Robinson is our producer, and we'd like to give a special thanks to A Collini and S Navarro who reviewed this episode.

Join our newsletter

checkmark Got it. You're on the list!
© For Your Life 2022, All rights reserved.