Laurence,   Several of the cluster sufferers I know get good relief from oxygen. I hope you're able to get it approved soon.   Some people use the injectable sumatriptan (Imitrex/Imigran) for cluster headaches because they're able to use it more times in one day than the other triptans. The maximum dosage is 12mg in a 24-hour period. Rather than use the autoinjector, they get the 6mg individual dose vials and use only 2mg per dose. Also, since the sumatriptan is a subcutaneous injection, it works more quickly than other triptans.   Still, there is a risk of medication overuse with any of the triptans if they're used more than two or three days a week. Take a look at Medication Overuse Headache - When the Remedy Backfires for more information on this.   Have you tried any preventive medications?   Good luck, Teri