
The altitude sickness pills, as I understand it, thicken the blood and help it to remain oxygenated, or something along those lines. It's supposed to mitigate the effects of apoxia.
I started summit day pretty dehydrated; that was the disadvantage of relying on the porters for water. They had to boil water for 15 minutes before giving it to us, so the turnaround was pretty slow; I'd give them my bottles in the evening and get them back, filled, in the morning, so I started every day with a hydration deficit. Had I known about this I'd have brought an extra bottle so I'd have water to drink while waiting for refills.
I could have just gone to the stream near camp at most of them to get water since I brought my MIOX purifier with me, but that wasn't an option at Kibo Hut -- there's no water there, so the porters had to bring it up from around 2 miles away.
The guides are on the ball about this; when they see someone starting to lose coherence, they start asking questions, and if the answers indicate altitude sickness, they send you back to base camp. In my case, a porter and a guide stabilized me while we scree-skated post-haste back to Kibo Hut -- the guide said that he'd seen people get like me before, and it usually cleared up once they got below 16,000 feet.
We had enough guides along on our ascent that we could send some people back without forcing the entire group to give up. So we were covered -- the Kilimanjaro mountain guides know what they're doing, and they take safety very seriously.
We were lucky -- we had cloudy weather when we started, which kept the temperatures at low elevations moderate (so, no hiking in 95 degree heat), but the sky was crystal clear on summit day, so the sun warmed us up pretty nicely. The clouds floating in around Mawenzi in that picture didn't reach us; the sky was crystal clear when we started our descent -- so by the time we got back down to 12,000 feet it was pretty hot.
This was my first real big-mountain experience, and I didn't take any pills for altitude, so I think I did pretty well in getting to 18,600 feet in spite of starting with a hydration deficit. Hopefully next time I'll be better hydrated and I'll not only make it to the summit, but also have enough presence of mind to operate my large-format camera and get some really nice shots from up there
