Oestrogen falls, and with it the ceramides, sebum and water-holding that keep skin sealed and plump. Androgens do not fall at the same rate, so their effects show through. Dryness, itch, reactivity and a flatter face come from the first change. Breakouts and chin hairs come from the second.
There is one mechanism under most of it. The outer layer of skin is cells held together by lipids, and oestrogen supports the three things that seal it: the ceramides that make up most of that mortar, the sebum that oils the surface and the hyaluronic acid that holds water. Research comparing women before and after menopause found fewer and shorter ceramides afterwards, and no such loss in women taking hormone therapy. Blood oestradiol tracked with how much ceramide was there. Less is held in and more is lost out, and the rougher surface you see in the mirror is where that ends up.
Below the surface, the same hormone supports collagen. Reviews of menopause and skin describe a strong correlation between skin collagen loss and oestrogen deficiency, with collagen loss described as rapid in the first years around the last period, and oestrogen use afterwards reported to raise collagen content, dermal thickness and elasticity. Less scaffold under a thinner surface is the structural half, and it reads as flatness rather than as a line you can point to.
Then the second direction. Ovarian oestrogen falls faster than the androgens do, so what was a background signal becomes a visible one. The same shift arrives at two different follicles, a sebaceous one on a jawline and a hair follicle on a chin, and nothing new has been added. The counterweight has gone, which is why the woman with her first breakouts in twenty years and the woman with two chin hairs are describing one change, not two.
Everything else on this page is that mechanism landing somewhere specific. A thinner barrier stings on products that suited you for years. A thinner, drier barrier itches, and warmth amplifies it. Sensitivity is reported more often after the menopause than before it. Naming which one you have matters because the second step of the routine differs, and the most common self-inflicted problem of this decade is treating an androgen change with something that strips an already thin barrier.
The usual causesfewer ceramidesless sebumless water heldless collagen underneathandrogens showing througha barrier that reacts to what it used to tolerate