PURPOSE: Our aim was to review the existing literature to document oxygen's therapeutic effect on cluster headache.

METHOD: A PubMed search resulted in 28 hits, and from these and their references we found in total 11 relevant studies. We included six studies that investigated the efficacy of oxygen treatment. One study is observational and the remaining five are RCTs. Another five studies were on hyperbaric oxygen treatment hereof two case studies.

CONCLUSION: Oxygen therapy can be administered at different flow rates. Three studies investigate the effect of low-flow oxygen, 6-7 l/min, and found a positive response in 56%, 75% and 82%, respectively, of the patients. One study investigates high-flow oxygen, 12 l/min, and found efficacy in 78% of attacks. The effect of hyperbaric oxygen therapy has been investigated in a few small studies and there is evidence only for an acute, but not a prophylactic effect. Despite the fact that only a few high-quality RCT studies are available, oxygen treatment is close to an ideal treatment because it is effective and safe. However, sufferers of cluster headache do not always have access to oxygen because of logistic and financial concerns.