Quote Originally Posted by KnottedYet View Post
You can also get pins and needles in the distal ends of extremities when your blood becomes alkaline from blowing off too much carbon dioxide. (lactic acid produced from exertion acts to help balance out the acidity/alkalinity of the blood, but when you stop the exertion there may be a lag before your breathing rate readjusts)

Heavy breathing could be the culprit (it often is for me) but certainly bringing it up to your doc is a very good idea.
This is really interesting. As soon as I saw this thread title my first thought was of diamox (acetazolamide) which I took for a few weeks in Peru while trekking at high (15K+) altitude. This drug causes major tingling and pins-n-needles at the extremities (hands, feet, face) which can be very annoying as you are constantly pawing at your face to get the spiderwebs off. Eesh.

Most of the discomfort of mild altitude sickness (nausea, headaches, etc) are due to the blood becoming more alkaline as people tend to hyperventilate due to hypoxia in the thin air. This drug inhibits carbonic anhydrase and acidifies the blood, which relieves these symptoms. So... is the tingling caused by acidity or alkalinity? Or, maybe going too far in either direction on the pH scale can cause this? Hmmm...