Headache caused immediately, or after a delay, by acute exposure to histamine.
Histamine has similar effect whether administered subcutaneously, by inhalation or intravenously. The mechanism is primarily mediated via the H1 receptor, and is almost completely blocked by mepyramine.
Histamine causes an immediate headache in most people, but can also cause a delayed headache in migraineurs, which fulfils the diagnostic criteria for 1.1 Migraine without aura. In people with 2. Tension-type headache, histamine may induce a delayed headache which has the characteristics of that disorder. These delayed headaches occur, on average, 5-6 hours after exposure. People with 3. Cluster headache develop delayed headache with the characteristics of that disorder only during cluster periods, usually 1-2 hours after exposure.