Dehydration and Headache.

PURPOSE OF REVIEW: We define dehydration and its relationship to pain physiology including both primary and secondary headache disorders.

RECENT FINDINGS: Intravenous fluids administered for acute migraine attacks in an emergency department setting have not been shown to improve pain outcomes. However, increased intravascular volume before diagnostic lumbar puncture may reduce the frequency of post-lumbar puncture headache from iatrogenic spinal fluid leak. Maintenance of euhydration can help treat orthostatic and "coat-hanger" headache due to autonomic disorders. Similarly, prevention of fluid losses can mitigate secondary headaches provoked by dehydration such as cerebral venous thrombosis or pituitary apoplexy. Dehydration alone may cause headache, but oftentimes exacerbates underlying medical conditions such as primary headache disorders or other conditions dependent on fluid balance.