Can I use a retinoid and an exfoliating acid like salicylic acid at the same time?

If you're newer to active ingredients, it's gentler to introduce them separately rather than layering them in the same routine, because stacking a retinoid with a strong exfoliating acid like salicylic acid (a BHA) can add up to cumulative stinging and dryness, especially on sensitive skin. A common, low-drama approach is to stagger them — for example on alternate nights — so each has room to work while your barrier keeps up. If your skin is already well adjusted to both, a salicylic-acid step and a retinoid can coexist, but bring the second one in gradually and buffer with calming, barrier-supporting ingredients like niacinamide, ceramides or hyaluronic acid. The exact strengths that make this comfortable are the kind of detail the app tracks. This is cosmetic reference, not medical advice — if your skin is very reactive, go slowly or check with a professional.