Retinoids

Skin cell growth

As skin cells or keratinocytes divide and grow, they move through the epidermis of the skin to the upper layers where they differentiate and undergo a hardening process known as keratinisation and cornification. The hardened cells eventually die and are shed to make way for new skin cells.

Modifying skin cell behaviour

Tretinoin is a retinoid and is an active metabolite of Vitamin A that binds to intracellular receptors in skin cells and modifies the way skin cells behave. Tretinoin stimulates skin cell growth and this includes hair follicles. It also blocks skin cell differentiation and the hardening processes of the outer skin layer. It is thought that tretinoin prolongs the anagen phase of hair growth and in this way promotes hair growth. Therefore, although it does not prevent hair loss directly, tretinoin may be able to slow down the progression of hair follicle miniaturisation and even promote the growth of new hair.

Retinoids in combination hair loss products

Tretinoin is also used in combination with minoxidil and is thought to help reduce hair loss by increasing the absorption of minoxidil through the skin, as well as providing an additive effect with minoxidil to promote hair growth.