Table 1.

The history of oxygen used for cluster headache

Study	Year	Findings
Alvarez et al.15	1940	First use of oxygen for headache at a flow rate between 6 and 8 L/min.
Horton16	1952	First description of oxygen used for histamine cephalalgia.
Horton17	1955	Oxygen treatment in 1176 patients with histamine cephalalgia.
Horton7	1961	He raised the vasoconstrictive effect of oxygen in histamine cephalalgia.
Kudrow et al.18	1981	First systematic study on oxygen used for cluster headache.
Fogan et al.12	1985	Crossover study found that oxygen was more effective than room air.
Cohen et al.19	2009	Oxygen at 12 L/min, as well as at 7 L/min, was effective.