Skincare actives combination checker
Most irritation does not come from a bad product but from two good ones used the same evening. Pick two ingredients and see whether they work together, belong on alternate nights, or cancel each other out.
The verdicts are general rules for over-the-counter strengths. Sensitive or reactive skin needs longer gaps, and dermatologist-prescribed treatments come with their own instructions, which override any general rule.
Frequently asked questions
Does niacinamide really cancel vitamin C?
No. The idea comes from a 1960s study run at high temperatures on unstable forms. At skin temperature and in modern formulas the combination is stable.
How do you alternate two strong actives?
The simplest way is by evening: retinol on Monday, Wednesday and Friday, acids on Tuesday and Thursday, moisturiser only on the rest.
Should the same active go on morning and night?
Rarely. Vitamin C suits the morning, under sunscreen; retinol and acids belong at night because they make skin more sun-sensitive.