26. Benzoyl Peroxide - an oldie but a goodie

Doctor Jacob here today, and we're talking about benzoyl peroxide - an oldie but a goodie. This is part of our series talking about the topical treatment of acne, and if you haven't had the chance already you can go back and listen to the prior episode talking about topical retinoids, because almost everybody should be using one of those. So let's talk about benzoyl peroxide.

Benzoyl peroxide is a topical anti-acne agent which is widely available. It's the main ingredient of the popular Proactiv line of products, and basically it's also in many other acne products available from other companies and the store brands. It comes as bar soap, as a liquid body wash to be used in the shower, or face wash, and it also comes as leave-on formulations, for example leave-on gels. The concentrations of benzoyl peroxide that are used in the treatment of acne range anywhere from 2% all the way up to 10%. In general, I prefer lower strength concentrations because they're less irritating and there's no evidence that the higher strength is necessarily more effective than the lower strength concentrations. But there is certainly evidence that the higher concentrations can be more irritating.

Benzoyl peroxide is indeed antibacterial. It decreases oil production and it helps break down comedones, which are clogged pores, the salient feature of acne. Unlike an antibiotic, bacteria cannot develop resistance to benzoyl peroxide. Like peroxide, it works by basically creating some oxidative stress to the bacteria and damaging it.

The mechanism is very interesting in that the bacteria can't develop resistance to it, like for example they can to erythromycin, which is one of the topical antibiotics that used to be widely used, but now is kind of falling by the wayside because most of the acne-causing bacteria are now resistant.

Benzoyl peroxide is good for use both on and off the face. It can be used on the face, on the neck, on the trunk (the chest, back, shoulders). Be careful though, because overuse can lead to a little bit of irritation, also called irritant dermatitis, sometimes known as a white peeling. This type of white peeling or flaking of skin just means that the patient needs to back off on using it; maybe using it every other day if they were doing once a day. Or if you started off at twice a day, you can back off to just every day. The chance of getting the irritant dermatitis is dependent both on how strong a concentration you're using, as well as the frequency of your use of that product. So when you start to see if you have irritant dermatitis, if you're starting to get dry, flaky, white peeling, back off on the formulation of your product in terms of the concentration, as well as reduce your frequency of use.

Relatively speaking, allergy to benzoyl peroxide is really rare. That would be an itchy response to the benzoyl peroxide when it's applied both on and off the face. If you want to do a test to see if a patient is allergic to benzoyl peroxide, you can put a little drop of benzoyl peroxide gel on the skin of the arm and cover it with a band-aid, and leave the band-aid in place for 48 hours without getting that area wet for that time period. If an itchy rash develops where that drop of the gel was, then you know the patient is allergic to benzoyl peroxide and you have to avoid it. True allergy to benzoyl peroxide is pretty rare.

Topical benzoyl peroxide works well in combination with either a topical retinoid or a topical antibiotic, such as clindamycin. There are combination products which are formulated with for example two medicines in one, and we'll talk more about those in a later episode.

Regarding something called tolerance, tolerance to benzoyl peroxide means that you started using it and you had a good result at first, but then your skin kind of built up a little bit of a resistance and it doesn't work as well. That can be seen, and what you have to do is increase your frequency of use of the product, or increase the concentration of the product just a little bit. You can see that happening after around two to three weeks.

Regarding its use in pregnancy, it's currently by the Food and Drug Administration as category C, meaning that we need more evidence to decide. In other countries aside from the United States, benzoyl peroxide is given a more friendly pregnancy category rating, which it's generally thought of as accepted as being safe for use. However, given the lack of data regarding the use of benzoyl peroxide, I'd recommend discussing this with your obstetrician, but many dermatologists consider it safe during pregnancy. During breastfeeding it's okay in my books, as long as it's not getting on the baby's skin.

One thing which is annoying about benzoyl peroxide is that it bleaches clothing. It's a peroxide, so if you have dark-colored clothing, or towels or pillow cases, it can lighten the color. That can be annoying, so you have to figure out when in the day you want to use it as to minimize its impact on your colored wardrobe.

Finally, although I mentioned that benzoyl peroxide works well in combination with retinoids, it shouldn't be co-applied at the same time with retinol, tretinoin or tazarotene. Only the retinoid adapalene could be used at the exact same time of day for application, or even made into the same product, where adapalene and benzoyl peroxide come mixed together by the manufacturer in one product. That product is called Epiduo, or Epiduo Forte, which is the newer and stronger version of the product. But don't mix it at the same time with tretinoin, retinol or tazarotene, because you can weaken the retinoid.

So that's benzoyl peroxide, an oldie but a goodie, and a staple of many acne treatment regimens.

I'm Doctor Jacob, we'll see you next time.