If you suffer from acne, you're probably no stranger to benzoyl peroxide and salicylic acid. Both ingredients promise to do away with pesky breakouts, dry up pore-clogging sebum, and prevent future pimples from making an appearance. But how much do you really know about their key differences and what each one does to your skin? For a clear and concise breakdown, including the pros and cons of each acne-fighting ingredient, I spoke with Los Angeles board-certified dermatologist Dr. Christine Choi Kim.
What is benzoyl peroxide?
Benzoyl peroxide is an acne-clearing ingredient most notable for diminishing bacteria and absorbing excess sebum. "It is a topical compound that has been used to treat acne since 1934. It is antibacterial, anti-inflammatory, keratolytic—it breaks up the top layer of dead skin cells—and comedolytic, which means it dissolves blackheads and whiteheads," explains Dr. Kim.
How does benzoyl peroxide work?
Dr. Kim continues: "After application, benzoyl peroxide degrades and releases oxygen which is lethal to cuti bacterium acnes, a bacteria that plays a role in acne formation. Because it kills the bacteria and does not just slow down its growth (like antibiotics do), benzoyl peroxide does not contribute to bacterial resistance." And while it can improve acne when used by itself, says Dr. Kim, its efficacy is enhanced when combined with topical antibiotics and retinoids.
What is salicylic acid?
Salicylic acid is a slightly more gentle ingredient and targets the cause of acne. Says Dr. Kim: "Salicylic acid is a beta-hydroxy acid derived from willow bark...It works well alone and in combination with alpha- hydroxy acids like glycolic acid and lactic acid."
How does salicylic acid work?
"It's oil-soluble and can dissolve the debris of dead skin cells and sebum that clogs pores," says Dr. Kim. That’s what makes it a hero ingredient in over-the-counter blemish-fighting products. Added bonus: it has anti-inflammatory properties and belongs to the same chemical family as aspirin.
What's the difference between benzoyl peroxide and salicylic acid?
"The biggest difference between the two ingredients is that benzoyl peroxide has antibacterial properties and is more helpful for inflammatory acne lesions like tender red papules and pustules," explains Dr. Kim. "However, salicylic acid has stronger comedolytic effects, so it is more effective at treating and preventing blackheads and whiteheads. Because of their different advantages, they work well together."
How should I use benzoyl peroxide and salicylic acid?
Both benzoyl peroxide and salicylic acid can be found in a variety of forms, which makes them both very versatile. "Benzoyl peroxide is an active ingredient in cleansers, gels, creams, lotions, and foams. Salicylic acid can be found in cleansers, toners, moisturizers, and even concealers," says Dr. Kim.
But it's important not to use too many products that have active ingredients all at the same time. That’s a recipe for disaster—it may cause irritation and a case of dermatitis. "I usually recommend choosing just one product that has benzoyl peroxide and one that has salicylic acid," says Dr. Kim. "Start slowly in the beginning, alternating days until your skin gets used to [both products] with no signs of peeling, redness, or irritation."
Either product can be incorporated in your morning or nighttime skincare routine. Once you build your tolerance you can try applying both daily. "If your dermatologist adds prescription products [to your skincare routine], you may need to to [decrease] your use of benzoyl peroxide and salicylic acid," says Dr. Kim. "Be careful not to apply these active ingredients near the delicate skin around the eyes. Acne treatments are best used in a thin layer on the affected areas of your face and body–not just on your existing acne spots." The idea is to get ahead of your acne and prevent the development of future breakouts.
What are the pros and cons of benzoyl peroxide?
"The benefits of benzoyl peroxide are a reduction in inflammatory acne lesions as well as some breakdown of comedones. However, benzoyl peroxide can bleach dark clothing, bedding, and even your hair and irritation is the biggest potential side effect," explains Dr. Kim. "In studies, benzoyl peroxide is equally effective at concentrations of 2.5 percent, 5 percent and 10 percent, but its irritation profile increases with higher concentrations." Start with a lower concentration to maximize effectiveness and minimize irritation.
What are the pros and cons of salicylic acid?
"The benefits of salicylic acid are a reduction in blackheads and whiteheads; it also has some anti-inflammatory properties. Irritation is, again, a possible side effect," says Dr. Kim. "It is usually used in concentrations ranging from 0.5 to 2 percent in acne products. If you have sensitive skin, start with lower concentrations and use it every other day to start. And avoid salicylic acid if you are allergic to aspirin or other NSAIDs."
Any final thoughts?
With both ingredients, it's important to follow up with a moisturizer to minimize dryness and irritation. "Don’t use on skin that is compromised by sunburn, windburn, open sores, or eczema-type rashes," advises Dr. Kim. And it's even more important to apply SPF daily, as both ingredients sensitize your skin to UVA and UVB rays.