Acne sufferers are no strangers to benzoyl peroxide and salicylic acid. Both acne-fighting ingredients promise to get rid of pesky breakouts, dry up the sebum blocking pores, and prevent future acne from appearing. For a clear and concise breakdown of benzoyl peroxide and salicylic acid, including the pros and cons of each hero ingredient, Marie Claire spoke with Dr. Christine Choi Kim, a board certified dermatologist in Los Angeles (opens in new tab).

Benzoyl peroxide is an acne-clearing ingredient noted for reducing bacteria and absorbing excess sebum. Benzoyl peroxide is a topical compound that has been used to treat acne since 1934," Dr. Kim explains. It has antibacterial, anti-inflammatory, keratolytic (breaks down the top layer of dead skin cells), and comedolytic (dissolves blackheads and whiteheads) properties."

"After application, benzoyl peroxide decomposes and releases oxygen, which is deadly to acne bacteria (bacteria involved in acne formation). Benzoyl peroxide kills the bacteria and does not slow their growth like antibiotics do, so they cannot become resistant."

And while benzoyl peroxide can improve acne when used alone, Dr. Kim says its effectiveness is enhanced when used in combination with topical antibiotics and retinoids.

"The benefits of benzoyl peroxide are reduction of inflammatory acne lesions and some destruction of comedones. However, benzoyl peroxide can bleach dark clothes, bedding, and even hair, and inflammation is the biggest side effect," Dr. Kim explains. Studies show that benzoyl peroxide is equally effective at concentrations of 2.5 percent, 5 percent, and 10 percent, but the irritation profile increases as the concentration increases." Therefore, to maximize effectiveness and minimize irritation, start with lower concentrations.

Salicylic acid is somewhat milder than benzoyl peroxide and targets the cause of acne. Salicylic acid is a beta-hydroxy acid derived from willow bark," Dr. Kim explains. 'It works well alone or in combination with alpha-hydroxy acids like glycolic acid and lactic acid.'

"It is oil soluble and can dissolve dead skin cells and sebum debris that clog pores," says Dr. Kim. That's why it is the hero ingredient in commercial blemish-removing cosmetics." As an added bonus, salicylic acid has anti-inflammatory properties and belongs to the same chemical family as aspirin.

"The benefit of salicylic acid is the reduction of dark spots and whiteheads. It also has anti-inflammatory properties," says Dr. Kim. 'It is typically used in concentrations of 0.5 to 2 percent in acne products. People with sensitive skin should start with a lower concentration and use it every other day. Also, avoid salicylic acid if you are allergic to aspirin or other nonsteroidal anti-inflammatory drugs."

"The biggest difference between the two ingredients is that benzoyl peroxide has antibacterial properties and is more useful for inflammatory acne lesions such as tender red papules or pustules," Dr. Kim explains. Salicylic acid, however, is more effective in treating and preventing blackheads and vitiligo because of its strong comedo-eliminating action. Because of their different advantages, they work well together."

Both benzoyl peroxide and salicylic acid come in a variety of forms and are therefore very versatile. Benzoyl peroxide is the active ingredient in cleansers, gels, creams, lotions, and foams." Salicylic acid is found in cleansers, toners, moisturizers, and even concealers," says Dr. Kim.

It is crucial not to use too many products containing active ingredients at the same time. This can cause irritation and dermatitis. Says Dr. Kim, "I usually recommend choosing one benzoyl peroxide and one salicylic acid product." Start slowly in the beginning and alternate between the two products for a number of days until the skin becomes accustomed to [both products] and there are no signs of peeling, redness, or irritation."

Either product can be incorporated into a morning or evening skin care routine. Then, once tolerance is established, you can try applying both daily. If your dermatologist adds prescription products [to your skin care routine], he or she may need to [reduce] the use of benzoyl peroxide and salicylic acid," Dr. Kim says. 'Be careful not to apply these active ingredients near the delicate skin around the eyes. Acne treatments are best applied thinly to the affected areas of the face and body. The idea is to get ahead of the acne and prevent future breakouts.

It is essential that both ingredients be followed up with a moisturizer to minimize dryness and irritation. Dr. Kim advises, "Do not use on skin with sunburn, windburn, sores, or eczema." And it is even more important to apply SPF (open in new tab) daily. That's because both ingredients make skin more sensitive to UVA and UVB rays.