Robyn and I did take Oxygen on our hike and it was a blessing. We took 4 cans of flavored Big Ox.
www.thebigox.com and used just a few breaths short of all of it.
We were able to abate the headaches with in seconds and squelch the dizzyness right away, very worth it. Cans are a little big but weigh nothing, come in Mint or Tropical and have about 30 breaths per can. We took about 4 hits every 20 min above 13,000 feet.