Progesterone, also known as P4, is an endogenous steroid hormone, produced by the corpus luteum. It belongs to a group of steroid hormones called the progestogens, and is the major progestogen in the body. Progesterone is also a crucial metabolic intermediate in the production of other endogenous steroids, including the sex hormones and the corticosteroids, and plays an important role in brain function as a neurosteroid.
In cosmetic applications, when properly formulated, topical progesterone can slow certain age-related changes to skin. Most notably, it seems to positively impact skin’s elasticity. For this reason, Progesterone is used in anti-aging creams.