Salicylic acid and benzoyl peroxide are the two most widely available acne ingredients, and you will find them in cleansers, gels, toners and spot treatments. They work in different ways, so choosing the right one, or using both correctly, can make your routine much more effective.
Salicylic acid
What it is: a beta hydroxy acid (BHA) that is oil-soluble, so it can work inside the pore.
How it works: it loosens and dissolves the dead skin cells and oil that clog pores, and has a mild anti-inflammatory effect.
Best for: blackheads, whiteheads, oily skin and mild breakouts.
Typical strength: 0.5% to 2% in over-the-counter products.
Side effects: dryness, mild stinging or peeling, especially when started daily.
Benzoyl peroxide
What it is: an antimicrobial ingredient that releases oxygen into the pore.
How it works: it kills acne-causing bacteria and helps clear blocked pores. Bacteria do not develop resistance to it, which is why it is often combined with prescription antibiotics.
Best for: red, inflamed pimples and pustules.
Typical strength: 2.5% to 10%. Studies show 2.5% to 5% work about as well as 10% with less irritation.
Side effects: dryness, redness and peeling. It also bleaches fabric, so use white towels and pillowcases.
Which one should you choose?
- Mostly blackheads and whiteheads: start with salicylic acid.
- Mostly red, inflamed spots: start with benzoyl peroxide.
- A mix of both: many people do well using a benzoyl peroxide wash in the morning and a salicylic acid or retinoid product at night.
- Sensitive or dry skin: choose the lowest strength and a wash-off format, which is gentler than a leave-on gel.
Can you use them together?
Yes, but introduce them one at a time. Using both at full strength from the start often causes dryness and irritation. Start with one product for two to three weeks, then add the second on alternate days. Always follow with a non-comedogenic moisturizer and use sunscreen during the day.
Be careful when combining benzoyl peroxide with older retinoids such as tretinoin, as benzoyl peroxide can break tretinoin down. Applying them at different times of day avoids this. Adapalene is stable alongside benzoyl peroxide.
How long until you see results?
Both ingredients usually take 4 to 8 weeks to show clear improvement, and acne may look a little worse in the first couple of weeks. Stick with a product for at least 8 weeks before deciding it does not work.
When to see a doctor
If neither ingredient helps after two to three months, or your acne is moderate to severe, a doctor or dermatologist can recommend prescription options.
Related reading
This article is for general information only and is not a substitute for advice from a doctor or dermatologist.