Oxygen inhalation is effective for certain types of headaches and has a pain-relieving effect, but for most headaches, oxygen inhalation has no effect. In clinical practice, there are some patients with cluster headache who have a severe headache that lasts for an hour or so, and the headache is accompanied by eye pain and tearing, and the headache is relieved significantly within a few minutes after oxygen inhalation. However, for other patients with cluster headaches, oxygen inhalation is not effective in stopping the headache, and in some cases it has no effect at all. So oxygen inhalation is only effective for certain types of headaches or for a particular person, but not for most headaches.