Virtually everyone has experienced a headache—a nuisance arising from occasional stress or as payback for last night’s overindulgence. But for hundreds of millions of people, there are headaches, and then there are headaches. From blinding migraines to severe headaches known as “clusters,” chronic head pain can upend entire seasons of life. And perhaps owing to the ordinariness of the very word “headache,” these disorders are frequently trivialized. In The Headache, veteran science journalist Tom Zeller Jr. takes readers on an odyssey both intimate and panoramic, through his own decades-long struggle with cluster headaches and across the scientific landscape of a group of disorders that are—to the chagrin of sufferers—as much a curse as a cultural punchline. He visits cutting-edge clinics;interviews dozens of doctors, neurologists, and fellow headache patients;participates in clinical trials for multi-million-dollar new medicines;and even experiments with psilocybin in search of relief