Using Benzoyl Peroxide to Treat Acne


Benzoyl peroxide stops acne bacteria from reproducing.

Benzoyl peroxide is the world’s most frequently used treatment for acne infections. The key to success in treating acne with benzoyl peroxide, however, usually is to use less, not more.


  • Benzoyl peroxide is the world’s most frequently used treatment for acne.
  • The way benzoyl peroxide works is by irritating acne bacteria so they do not have the nutritional resources to reproduce. Since bacteria have a very short lifetime, in about 48 hours there are almost no bacteria left on the skin.
  • Traditional benzoyl peroxide gels only treat pimples.
  • Slow-release forms of benzoyl peroxide have an additional advantage. They also treat whiteheads and blackheads.
  • You probably will experience a slight burning sensation the first time you use benzoyl peroxide. Up to 2.5% benzoyl peroxide gel or up to 5.5% slow-release benzoyl peroxide usually do not cause significant irritation after the first use.
  • Not everyone should use benzoyl peroxide. If you have dark skin tones, be sure to use sun protection when you are using this product.

What Is Benzoyl Peroxide?

Benzoyl peroxide is a synthetic chemical that happens to imitate two natural substances. The benzoyl peroxide you get in a tube of face gel begins as toluene distilled from petroleum that is sent through three chemical reactions. When you put the product on your face it breaks down into benzoic acid and oxygen.

Benzoic acid has been used to treat skin infections since the 1890’s, when it was popularized as Whitfield’s ointment. Oxygen is toxic to some kinds of bacteria—although it is not especially toxic to acne bacteria. Benzoyl peroxide, incidentally, is poisonous to cats, so don’t let kitty lick your face if you have used benzoyl peroxide.

How Does Benzoyl Peroxide Fight Acne?

Benzoyl peroxide does not deliver a knockout blow to acne bacteria, but about 99% of bacteria die without reproducing themselves over a 48-hour period.

The oxygen released by benzoyl peroxide forms toxic free radicals of oxygen. Human skin has repair mechanisms that make it immune to these free radicals of oxygen. Acne bacteria have not quite as many repair mechanisms to help them maintain cellular integrity even when oxygen “burns” their cell membranes. One of the ways that benzoyl peroxide fights acne infection is by irritating acne bacteria and forcing them to spend energy in maintaining the integrity of their outer membranes. Since bacteria have a very short life span, any drain on their nutritional resources makes them more vulnerable to the human immune system, which is constantly releasing inflammatory hormones to dissolve them.

Recent Advances in Benzoyl Peroxide Products

Some pharmaceutical companies have started using microsphere technology to make smaller amounts of benzoyl peroxide equally effective for killing acne bacteria, with fewer side effects. Microspheres are made by mixing benzoyl peroxide, ethanol (the kind of alcohol in alcoholic beverages), a chemical called triethyl citrate, and a polymer used that can also be used to make plastics.

The mixture of chemicals creates microsponges that soak up benzoyl peroxide. These tiny sponges do not dissolve in water, but they can float in water. When the mixture of water and benzoyl peroxide microspheres is applied to the face, the microsponges release tiny amounts of benzoyl peroxide for several hours. Instead of using a large amount of benzoyl peroxide to kill a few acne bacteria all at once, microsphere technology makes it possible to use a small amount of benzoyl peroxide to kill a lot acne bacteria slowly.

There are two big advantages of “solubilized” and “microsphere technology” preparations of benzoyl peroxide. One advantage is that they don’t cause as much itching, tingling, burning, and dryness. Even a 5.5% concentration of solubilized benzoyl peroxide left on the skin, in one study, caused no more skin irritation that than a common skin wash rinsed away 30 seconds after application to the skin.

The other advantage of these modern formulations of benzoyl peroxide is that they get rid of whiteheads and blackheads as well as pimples. Regular benzoyl peroxide does not stay on the face long enough to peel the skin. Solubilized and microsphere benzoyl peroxide not only kill bacteria in pimples, they also break up clumps of dead skin that hold non-inflammatory blemishes in place and help pores drain.

Which Form of Benzoyl Peroxide Should You Use?

While the microsphere formulas are much better for fighting acne than the benzoyl peroxide gels that have been available for over 50 years, not everyone should use benzoyl peroxide. If you have rosacea, benzoyl peroxide may trigger formation of new small pimples due to irritation. Also, if you have Asian skin, failure to use sun protection when you use benzoyl peroxide may result in brown discoloration of the skin. Fortunately, there are many other products that also can clear up blemishes on rosacea-prone and Asian skin.

For everyone else, the most useful form of benzoyl peroxide will be either:

  • A controlled release product that contains microspheres or microsponges, available by prescription, up to 5% benzoyl peroxide, or
  • An over-the-counter benzoyl peroxide gel containing no more than 2.5% benzoyl peroxide.

The US Food and Drug Administration has authorized labeling benzoyl peroxide as GRASE, or generally regarded as safe and effective. The concentrations used in medical studies, however, are usually stronger than the concentrations used in over the counter products, because medical researchers want to make sure they get a measurable effect from their products, whether or not they cause irritation.

You want to get rid of acne, but you don’t want the side effects. That’s why you should start with either a 2.5% over-the-counter product or up to a 5.5% microsphere, controlled release, or time release benzoyl peroxide product for which you will most likely need a prescription.

It is possible to get up 10% benzoyl peroxide over the counter, without a prescription. This strength of benzoyl peroxide is OK if you are using it for spot treatment, or for treating back acne, but you don’t want to put it all over your face. Use low concentrations of benzoyl peroxide for treating your entire face, or use the lowest strength of benzoyl peroxide you can find until you are sure it is not causing skin irritation.

Just getting rid of acne bacteria is never enough to keep your complexion clear and vibrant. It is always necessary to have a regular program that includes both cleansing and moisturizing as well as simple, painless microdermabrasion to get rid of reminders of past treatment errors. One of the best sources for  the products you need for ongoing clear skin care is Exposed Skin Care.

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