Factors associated with headache in intravenous immunoglobulin treatment for neurological diseases.

Intravenous immunoglobulin-associated headache is not associated with an increased blood pressure after infusion but with a reduced heart rate, a slower infusion rate, female sex and seems to be influenced by baseline systolic blood pressure and age. A reaction to immunoglobulin aggregates, stabilizers, or vasoactive mediators are possible explanations. The absence of an association with body temperature does not suggest a systemic immune response as a cause for headache.