Why it happens
Benzoyl peroxide works by releasing oxygen, which is how it kills acne-causing bacteria. Tretinoin is easily oxidised, and that same reaction degrades it. Light makes tretinoin less stable too.
Not every retinoid behaves this way. Adapalene is stable alongside benzoyl peroxide — there are prescription products that combine the two — and some newer tretinoin formulations are more resistant. Which one you have matters, and that's a question for whoever prescribed it.
The usual split
Benzoyl peroxide in the morning, often as a wash you rinse off, and tretinoin at night. That keeps them apart and puts the light-sensitive one on overnight.
Both are drying. Using them on the same day still adds up, so a plain, fragrance-free moisturiser and daily sunscreen do a lot of the work of making this combination tolerable.
Worth knowing
Benzoyl peroxide bleaches fabric — pillowcases and towels especially. White ones save a lot of grief.
If tretinoin was prescribed as part of an acne plan, the prescriber may already have a reason for a particular combination. Follow that over anything general, including this page.
Common questions
- Can I use benzoyl peroxide in the morning and tretinoin at night?
- That's the common split, and it keeps the two from breaking each other down. If both were prescribed, use them the way your prescriber told you.
- Does benzoyl peroxide deactivate retinol too?
- The research is mostly about tretinoin. Adapalene is known to be stable alongside benzoyl peroxide; for over-the-counter retinol, keeping them at different times of day is the safe default.
- Can I use a benzoyl peroxide wash with tretinoin?
- A wash that's rinsed off in the morning is one of the easier ways to use both, since little is left on the skin by the time tretinoin goes on at night.
