[channel_t]

I was about to say, I've brought friends from the US to Mexico City on a few occasions and it seems like the altitude (and maybe the pollution) has had strange and unpleasant effects on most people during the first couple days. A vertigo episode definitely doesn't sound far-fetched.

[capableweb]

I've found out that chewing coca leafs is an excellent way to combat side-effects from changing altitudes. Mostly socially acceptable in central/south america as well, so don't have to worry about that. Doesn't hurt that you could replace your coffee-intake with it as well :)