Estriol

Estriol is a naturally occurring oestrogen—one of three main forms produced in the body, alongside oestradiol and oestriol. In skincare, it is used in topical form at low concentrations, typically between 0.01% and 1%. Unlike systemic hormone replacement therapy, topical estriol works locally on the skin rather than entering the bloodstream significantly.Estriol is considered the weakest of the three main oestrogens, which is relevant to its safety profile. In skincare formulations, it is applied to the skin surface where it may interact with oestrogen receptors in the dermis and epidermis,…

Estriol is thought to work by binding to oestrogen receptors present in skin cells. These receptors influence various processes including collagen synthesis, water retention in the stratum corneum, and the production of natural moisturising factors. During hormonal transitions, oestrogen levels decline, which can impair these functions and contribute to visible signs of skin ageing.Because estriol is a weaker oestrogen, it may exert selective effects on skin tissue with potentially fewer systemic effects than stronger oestrogens—though topical application at low concentrations further limit…

Estriol is typically found in serums or creams formulated for mature or hormonally shifting skin. Apply to clean skin as directed by the product instructions, usually once or twice daily. Results are unlikely to be immediate; improvements in skin hydration and texture may develop over weeks of consistent use. If combining with other actives, introduce gradually and monitor your skin's response.

Topical estriol at cosmetic concentrations is generally well-tolerated with low risk of systemic absorption. Those with a personal or family history of hormone-sensitive cancers should consult a healthcare provider before use, as a precautionary measure.