A closer look
That pre-period headache isn't just routine stress; it's a violently orchestrated biochemical drop-off in your brain stem. During the late luteal phase of the menstrual cycle, blood estrogen levels fall off a literal cliff. This sudden hormonal vacuum causes the trigeminal nerve to panic and dump a massive payload of a chemical called CGRP into the brain's outer lining. The resulting blood vessel inflammation creates a throbbing, photophobic migraine that over-the-counter painkillers literally cannot touch.
