Can't be 100% sure ever, but usually oxygen knocks out hit until you get next one, although some say that after you feel pain diminished, you should still stay on oxygen for 5 minutes more at 15lpm just to be sure, you can support yourself with chugging Red Bull or similar drink containing caffeine and taurine as it has been known to aid us Clusterheads.

Hope that piece of info helped you a bit, hang in there!

With the O2 (oxygen) are you using a NON-rebreather mask, one with a bag on it?

The O2 will stop individual attacks, so another attack can happen later. Just use the O2 to abort the next and the next, etc.

If you don't have the mask with a bag there are ways to make what you have work as well as possible.

Good Luck, Don

Using only oxygen I tend to suffer re attacks within 10-20 minutes. For many years I was combining an oral cafergot with the oxygen for a 1-2 punch. 02 would knock it down, cafergot would buy me up to 12 hours pain free time.

At the suggestion of people here I am using energy drinks this cycle instead of the cafergot...Red Bull sugar free for me...the same way. My wife pours a Red Bull on the rocks ...for me as I start the 02. It's pretty much working as well as the cafergot at preventing the re attacks. Haven't used cafergot at all this cycle. Might be worth trying if you get the re attacks.

Joe

Its not always the same.  If I get on the o2 early in the attack it kills it quick and it's gone until the next one.  If im late it deadens the pain and when I stop the o2 too soon it'll come back, so I need to stay on it for a while.