Benzoyl Peroxide vs. Salicylic Acid: What's The Difference & Which Should You Use?

Becoming well-versed in the glossary of acne-fighting ingredients, we admit, is no walk in the park (the acids alone can be dizzying). But when those pesky blemishes pop up, you don't want to slather on any ol' ingredient and hope for the best—you need to make an informed choice based on your skin type.

There's no shortage of treatments to choose from, but let's start with two of the most popular: benzoyl peroxide and salicylic acid. They're often touted as the best solutions for managing acne, but it's important to know just when and how to use both of these powerful ingredients (hint: It depends on the type of acne you have). 

Like its cousin, hydrogen peroxide, benzoyl peroxide is antimicrobial—meaning it can kill bacteria. But while you should definitely steer clear of using hydrogen peroxide for acne (short answer: It's way too harsh for your skin), there's tons of research1 touting the latter as an effective acne treatment because of these antimicrobial properties. 

Why? Acne is a very complex chronic skin disease, with multiple factors at play in its formation. And one of those factors is a bacteria called P. acnes. P. acnes is actually the most abundant bacteria2 on the skin (it gets widely demonized, but it actually does a lot of good for us, including keeping our skin looking youthful). When the balance of P. acnes is off, and certain strains become too dominate, it can lead to breakouts. This is why aiming to keep a balance of your skin microbiome is so important for overall skin health.

So for those experiencing serious cases of acne, targeting bacteria can be an effective tool to reduce the lesions and reduce the chances of new ones forming. It's certainly not a permanent solution (it only works as long as you're using it, and you'll likely not want to use it long term as it's very drying), but it can definitely help folks to address moderate acne when needed.

It's available in both prescription form (read: you must visit a dermatologist) or OTC (so you can buy it your drugstore).

Salicylic acid comes from the beta-hydroxy acid (BHA) family. In case you need a refresher on those lovely BHAs, these acids are oil-soluble, meaning they can penetrate deep into your pores and unclog them at the source. Salicylic acid is a popular choice, as it can gently dissolve dead skin cells by breaking apart the bonds that hold them together, promoting cell turnover and smooth, bright skin underneath. It also works to dry out sebum in the skin, which can contribute to acne. So while benzoyl peroxide works by targeting the bacteria, this works by eliminating the oil and sebum.

Let us emphasize: Every product is different, so there aren't too many hard-and-fast rules. For example, benzoyl peroxide products (which tend to be more drying) might come buffered with hydrating actives to simultaneously lock in moisture while shrinking pimples in size. Similarly, salicylic acid might be paired with AHAs in combination treatments to further resurface the skin, which can actually cause irritation for some. See the nuance here? 

But generally, here's how to decide when to use both: 

Both benzoyl peroxide and salicylic acid are solid acne-fighting ingredients—it just depends on the type of acne you have. Your skin type also matters when choosing a treatment, as do the other skin care products in your routine, but the general verdict is this: For inflamed zits, an antibacterial benzoyl peroxide product is best (seek options buffered with hydrating actives to combat the drying effects); for pesky blackheads and whiteheads, oil-soluble salicylic acid is your guy. Want another modality to help you on your acne journey? Read our explainer on acne facials.