Oestrogen is a powerful anti-inflammatory hormone. When it declines in perimenopause, your body shifts into chronic low-grade inflammation — called inflammopause. It's the hidden driver behind joint pain, brain fog, fatigue and rising disease risk. A 2020 Journal of Neuroinflammation paper called perimenopause "a systemic inflammatory phase." Here's what that means for you — and what the evidence says to do about it.