Take it away, Mike: “The acute part refers to its rapid onset, not to its severity. Acute Mountain Sickness means you may get a headache, you could get lightheaded, you may experience nausea, insomnia, loss of appetite and shortness of breath when exercising. AMS is not a life threat, as long as it resolves itself within 24 hours.” Mike’s training prescribes that if you have these symptoms, “…eat and drink well, do some light exercise, take an aspirin and/or Vitamin I.” (Vitamin I is ibuprofen.) If the symptoms aren’t gone in a day, get the heck down from the mountain, toot sweet. Once down, the condition will most likely resolve.