Retinoids are a family of vitamin A derivatives used in skincare to encourage skin-cell turnover, support collagen, and improve fine lines, texture and uneven tone. They range from gentler over-the-counter retinol to stronger prescription tretinoin (a clinician decision).
Retinoids are among the best-evidenced anti-aging ingredients, but they commonly cause dryness, redness or flaking at first, so most people start low and slow and build up. Daily sunscreen is essential alongside them, and retinoids are avoided in pregnancy and breastfeeding. See retinol for skin.