My husband has had CH for 5+ years. Took 2 years to be "officially" diagnosed. I have done a lot of research on my own because the Neurologist / headache specialist has only presribed Imitrex for him. Hardly mentioned O2. After reviewing Oxygen therapy on this website and what exactly you need to effectively abort an attack....it has (so far) been doing the job. We have the big tanks M90 of O2, and more then two to get us through. We have a 15 lpm regulator and found that what all the research say's that 25 lpm works better at aborting an attack with uninterrupted flow does make a big difference !!!! However, our O2 provider does not provide a 0-25 lpm regulator. So to answer your question....so far the O2 has been doing it's job. We understand what you are going through....it is HELL for a loved one to watch their family member go through this and you feel very helpless. All you want to do is take their pain away and you can't.