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How Does Benzoyl Peroxide Work In Skin Cleansers?

Whether you've known it or not, you've probably been using benzoyl peroxide in products since you were a teenager and tried to erase your first blemish with on-the-spot treatments and cleansers.

"Benzoyl peroxide is an effective anti-acne medication," says dermatologist Dr. Linda Stein Gold. "It's effective in treating blackheads, whiteheads, and pimples. It kills the bacteria known to be involved with acne and, since bacteria don't develop resistance to this medicine, it will continue to be effective over time."

By killing bacteria, instead of just slowing it down, benzoyl peroxide is very good at helping manage breakouts. In skin cleansers, it works to prevent pimples before they form, as opposed to spot-treating them once they form. Research also proves their effectiveness: A 2005 study found that patients using a benzoyl peroxide cleanser and a retinoid once a day saw a 59 percent reduction in inflammatory acne compared to the 30 percent reduction seen in people who only used the retinoid [Del Rosso].

True to the study, benzoyl peroxide is rarely a stand-alone product. It's often mixed together with acne-clearing products and retinoids. [source: Dr. Joshua Fox] You'll usually see an improvement in acne after three weeks of using a product with benzoyl peroxide and maximum benefit after eight-12 weeks of use. [source:]

The amount of benzoyl peroxide that's best for your face depends on your skin type and how severe the acne is. "Using 5 percent of benzoyl peroxide in a prescription can work three times better than the 10 percent concentration in an over-the-counter product," says Dr. Joshua Fox, Medical Director of Advanced Dermatology PC, who says the percentage often varies from about 2.5 percent to 10 percent. The prescription creams may be optimized differently to help penetrate the acne with less benzoyl peroxide.

Benzoyl peroxide can be found in bars, lotions, creams and gels, so you can choose from a variety of different products based on your skin's needs. Though it is generally safe for most people, start using the skin cleanser once a day. If you notice that your skin is drying out or peeling, tingling, or becomes itchy, talk to your dermatologist.

Besides the irritation, it may also have a lightening side effect. It acts like bleach on clothing, so apply your facial cleanser with benzoyl peroxide after you get dressed (or undressed) to avoid ruining dark clothing.