First of all, there is no substitute for gradual acclimatization. Our bodies were not designed to fly to 5,000 ft., drive to a 9,000 ft. trailhead the same day, and immediately start the climb to a 14er. Those who manage to do this without serious illness are lucky. And they may not always be lucky. I read a few years ago about an experienced mountain climber who was trapped by storms at the top of Mt. Shasta, developed Acute Mountain Sickness, and succumbed within 24 hours to HACE (high altitude cerebral edema)--that's what causes the headaches.

Second, the one medically approved preventive for AMS is acetazolamide (diamox). It can be a partial substitute for acclimatization, but not aways total. My eldest son used it successfully during the year and a half he was stationed in Tajikistan as a military attache and occasionally going up into the high Pamirs. Please talk to your physician!

Third, if you haven't already, please read up on and learn to recognize the symptoms of severe altitude sickness (those migraine-style headaches are one symptom of HACE). It's serious stuff! Altitude sickness can be fatal or at least permanently damaging. One pair of visiting US servicemen my son encountered in Tajikistan insisted they didn't need diamox. They both developed HACE and, despite descending as soon as possible, one is permanently brain-damaged.

Here's one quick but good read about Acute Mountain Sickness.

PS--since this is a lightweight backpacking site: the Diamox pills and their container would be a lot lighter than those oxygen bottles!