Salicylic acid vs benzoyl peroxide: which works better?

The short answer: benzoyl peroxide has the stronger case

Benzoyl peroxide (BPO) has the stronger overall case. Salicylic acid (SA) is the gentler option, but its evidence is thinner. The 2023 AAD acne guideline03389-3/fulltext) gives BPO a strong recommendation and SA a conditional one, and it rates the evidence for SA as low certainty. You can see the same ranking in the AAD's acne clinical guideline.

Head to head, they tie on inflamed spots and split on everything else

The most direct comparison we found is a double-blind trial in mild-to-moderate acne that pitted a 0.5% SA regimen against a 2.5% BPO regimen. Inflamed lesions improved about equally. The differences showed up elsewhere, as the table shows. Double-blind OTC regimen trial03386-3/fulltext)

Most of the BPO advantage on non-inflammatory lesions came from closed comedones. The authors concluded that low-concentration SA is less drying and may be better tolerated over time. That is one small study, and we could not confirm full sample sizes or every statistic from the abstract.

Bigger analyses and older trials point the same way, with caveats

A meta-analysis of 23 RCTs with 7,309 patients found that 5% BPO combined with SA produced the largest reductions in inflammatory lesions at 2 to 4 weeks, at 55.2%, versus 33.4% for BPO alone. Indirect meta-analysis, PubMed Those were indirect comparisons, and the top performer was a combination, so the data cannot isolate what SA does by itself.

An older 4-week crossover trial of 30 people found that only a 2% SA cleanser significantly reduced comedones. Patients improved on SA in the first two weeks but worsened after switching to a 10% BPO wash. Salicylic acid cleanser vs BPO wash The sample is tiny and the study is dated.

A dermocosmetic RCT with 150 adults found a multitargeted SA cream outperformed 5% BPO on the investigator's global assessment at day 56, at 62.2% versus 50.0%. Dermocosmetic cream RCT That cream contains other actives, so it tells us about that product, not pure SA. For how SA works and where it fits in a routine, see our salicylic acid guide.

Safety: thin data on both

Neither ingredient has strong safety data. A Cochrane review of topical acne treatments rates the evidence on adverse events as very low certainty, and it is unclear whether SA causes more or fewer side effects than BPO. Cochrane review of topical acne treatments A separate BPO review reached a similar verdict on adverse-event rates. Topical benzoyl peroxide review

How to choose between them

Pick based on what your skin is doing, and change one thing at a time. The evidence supports a few reasonable starting points, and none of them is a guarantee.

• If your breakouts are mostly blackheads and whiteheads, SA is a reasonable first choice, since it had the clearer signal on comedones in the small trials.
• If you have red, inflamed bumps and no dryness concerns, BPO has the stronger guideline support.
• Avoid starting both on day one. The best combination data are indirect, so try one product consistently before adding another.
• If nothing improves after consistent use, see a dermatologist, who can look at prescription options.