The cytokine theory of headache.

Immune cell cytokines are proposed as the common mediators of headache. This unifying concept can not only account for headache, but also the prostaglandins, leukotrienes, platelet activating and vasoactive substances linked with headache, the varied symptoms associated with headache and the high incidence of headache with depression, infectious disease, trauma and in premenopausal women. The immune system as the central mediator of headache is consistent with the promoting effect of estrogen, the abortive activity of cortisol and the prophylactic properties of fish oil and evening primrose oil. This hypothesis provides a unified mechanism to explain headache triggered by food, infectious disease or trauma.