These are the two acne ingredients in every drugstore aisle, and they are not interchangeable. They treat different parts of the same problem.
Acne starts with a clogged pore. Bacteria then multiply inside the clog, and that is when the pore turns red and sore. Salicylic acid works on step one. Benzoyl peroxide works on step two.
So the useful question is not "which is stronger?" It is "where is my acne getting stuck?"
These two meet in exactly one place, the pore row — and even there they do different jobs: salicylic acid dissolves the plug, benzoyl peroxide kills the bacteria that move into it. Salicylic acid picks up an extra inflammation credit from its aspirin-family chemistry. Neither reaches the dermis, and neither does anything for pigment directly, which is why the marks left behind after a breakout need a separate ingredient.
Blackheads and whiteheads | Salicylic acid | Moderate
These are pure clogging with no infection. Salicylic acid dissolves in oil, so it can get down inside a pore full of oil and break up the plug. Benzoyl peroxide mostly works at the surface.
Red, sore, inflamed pimples | Benzoyl peroxide | Strong
It kills acne bacteria directly, and it is the only common acne ingredient that bacteria do not become resistant to. A Cochrane review of 120 trials found people rated their acne as improved more often on benzoyl peroxide than on placebo, a risk ratio of 1.27 — though the reviewers graded that evidence as low-certainty (Cochrane, 2020).
Back and chest acne | Benzoyl peroxide | Consensus
A wash is easy to use over a large area, and it rinses off before it can dry the skin out too much. Watch your towels and sheets — it bleaches fabric permanently.
Oily skin and large pores | Salicylic acid | Moderate
It keeps pores clear over time, and clear pores look smaller.
Sensitive or easily dried skin | Salicylic acid | Moderate
It is the gentler of the two. In the Cochrane review, people were about twice as likely to stop treatment because of side effects on benzoyl peroxide as on placebo — usually redness, itching, or burning.
Skin of color | Salicylic acid, usually | Moderate
Both work. The concern with benzoyl peroxide is not the drug, it is the irritation — and irritation is what leaves dark marks on deeper skin tones. In a 12-week randomized trial where over half the participants had skin types IV–VI, a salicylic acid routine matched a prescription adapalene and benzoyl peroxide gel on acne severity while causing significantly less tightness and dryness (J Cosmet Dermatol, 2024). That trial was funded by the maker of the salicylic acid products.
Direct head-to-head evidence | Neither — it is thin | Limited
Worth saying plainly: there is very little direct comparison between these two. The Cochrane review found that trials of benzoyl peroxide versus salicylic acid did not report patient-rated improvement at all. Most of what is written online about which is "stronger" is inference, not trial data.
Using both is the standard approach, and it is easy — because they suit different steps in a routine.
The usual setup:
- Wash: benzoyl peroxide 2.5–5%, left on for a minute, then rinsed.
- Leave-on: salicylic acid 2% at the other end of the day.
Don't layer them at the same moment. Not because they cancel out — they do not — but because stacking two drying actives is how people end up with a raw, peeling face and quit both.
Pick just one if: your breakouts are almost all blackheads and clogged bumps → salicylic acid. Your breakouts are almost all red and sore → benzoyl peroxide.
One caution: benzoyl peroxide can inactivate tretinoin in some formulations. If you use a prescription retinoid, apply them at different times of day unless your product is specifically made to combine them.
When to move on: if 12 weeks of consistent use has not changed much, the issue is usually that your acne needs a retinoid or a prescription — not a higher percentage of the same ingredient.