Nobody warned me that oestrogen was responsible for keeping my skin moisturised. I had used the same cleanser, the same moisturiser and the same routine for years. Then sometime around 42 my skin started changing. It felt dry and tight after cleansing. Fine lines appeared that were not there before. My skin felt sensitive in ways it never had. Products I had used for years suddenly felt like they were doing nothing. I thought I needed better products. What I actually needed was to understand what was happening. Here is the simple version. Oestrogen plays a direct role in collagen production, oil production and skin barrier function. When oestrogen starts to shift during perimenopause all three change simultaneously. Your skin produces less of its own moisture. The barrier that keeps moisture in weakens. And the collagen that keeps skin plump and firm starts to decline faster.