Histamine Intolerance & Migraine

Histamine is a major cause of migraines. Histamine increases nitric oxide, which causes vasodilation (ie expansion) of blood vessels.  Vasodilation increases blood flow to the brain.  The nervous system responds to this increased blood flow with symptoms of pain, flashing lights, double vision, vertigo, increased sensitivity to light, smells and noise as well as nausea, vomiting and diarrhoea.