Retinoids, are derivatives of vitamin A that can be found in nature from animal and plant sources, although most commercially available retinoid products are produced synthetically in the lab.
Retinoids are molecules that bind to and activate retinoic acid receptors to influence the proliferation (cell growth & division) and differentiation (unspecialized to specialized) of cells. This effectively helps reduce visible signs of aging, boost collagen production; which in turn reduces the appearance of fine lines and wrinkles.
Retinoids can also help treat various pigmentation disorders like melasma and post-inflammatory hyperpigmentation. It causes inhibition of tyrosinase and epidermal melanin dispersion.
Depending on the type of retinoid used, It can also interfere with pigment transfer to keratinocytes and accelerate pigment loss by triggering desquamation (shedding of dead skin cells from outermost layer of the skin).
Most common types of OTC retinoids are retinol, retinyl esters, and retinaldehyde. The type and percentage levels used in formulations mean they all work in different ways which dictate the results achieved.