Acute Mountain Sickness (AMS) or Altitude Sickness can occur when the human body is exposed to high altitude. It affects everyone differently and some more severely than others. Of course it helps to be fit and healthy, but AMS has total disregard for experience and fitness. You may have trekked previously at altitude and not been effected, but another time you may experience symptoms.
Mild AMS
Symptoms include headaches, feeling tired and fatigued, loss of appetite, shortness of breath, swelling of hands and feet, stomach upset, nausea, dizziness, pins and needles, inability to sleep – generally feeling a bit rough!
Moderate AMS
Severe headaches that are not relieved by medication, nausea and vomiting, increasing weakness and fatigue, shortness of breath, decreased coordination (Ataxia).
Severe AMS
Shortness of breath at rest, inability to walk, decreasing mental status, fluid build in lungs or brain causing swelling. The only way to alleviate severe AMS is to receive medical attention and to descend to a lower altitude immediately.
High Altitude Pulmonary Oedema (HAPO) and High Altitude Cerebral Oedema (HACO) are two, more serious and life threatening conditions that are associated with altitude sickness and occur when an individual has not been able to acclimatise properly or has climbed too quickly. Symptoms that are not assessed or remain untreated can eventually result in either of these conditions, where lack of oxygen can result in leakage of fluid through the capillary walls into either the lungs or the brain causing swelling. Both conditions require immediate evacuation and hospitalisation.