If your skin flares up, your gut feels reactive, or you find yourself flushed, itchy, or anxious around your period or during perimenopause, you’re not imagining it. There’s growing evidence that female hormones can directly influence immune cells called mast cells, changing how much histamine your body releases. These hormone–immune interactions may explain why some women experience cyclical symptoms that cross several systems — skin, digestion, mood, and energy — yet have never been fully explained by hormones alone.