Left: A woman at normal<unk> . Right: The same woman with a swollen face while trekking at high<unk>  (Annapurna Base Camp, Nepal; 4130 m). People have different susceptibilities to<unk> ; for some otherwise healthy people, acute<unk>  can begin to appear at around above sea level, such as at many mountain ski resorts, equivalent to a pressure of . This is the most frequent type of<unk>  encountered. Symptoms often manifest within ten hours of ascent and generally subside within two days, though they occasionally develop into the more serious conditions. Symptoms include headache, confusion, fatigue, stomach illness, dizziness, and sleep disturbance. Exertion may aggravate the symptoms. Those individuals with the lowest initial partial pressure of end-tidal pCO2 (the lowest concentration of carbon dioxide at the end of the respiratory cycle, a measure of a higher alveolar ventilation) and corresponding high oxygen saturation levels tend to have a lower incidence of acute mountain sickness than those with high end-tidal pCO2 and low oxygen saturation levels. Primary symptoms Headaches are the primary symptom used to diagnose<unk> , although a headache is also a symptom of dehydration. A headache occurring at an<unk>  above a pressure of combined with any one or more of the following symptoms, may indicate<unk> : Disordered System Symptoms Gastrointestinal Loss of appetite, nausea, vomiting, excessive flatulation Nervous Fatigue or weakness, headache with or without dizziness or lightheadedness, insomnia, “pins and needles” sensation Locomotory Peripheral edema (swelling of hands, feet, and face) Respiratory Nose bleeding, shortness of breath upon exertion Cardiovascular Persistent rapid pulse Other General malaise Severe symptoms Symptoms that may indicate life-threatening<unk>  include: ; Pulmonary edema (fluid in the lungs) : Symptoms similar to bronchitis : Persistent dry cough : Fever : Shortness of breath even when resting ; Cerebral edema (swelling of the brain) : Headache that does not respond to analgesics : Unsteady gait : Gradual loss of consciousness : Increased nausea and vomiting : Retinal hemorrhage The most serious symptoms of<unk>  arise from edema (fluid accumulation in the tissues of the body). At very high<unk> , humans can get either high<unk>  pulmonary edema (HAPE), or high<unk>  cerebral edema (HACE). The physiological cause of<unk> -induced edema is not conclusively established. It is currently believed, however, that HACE is caused by local vasodilation of cerebral blood vessels in response to hypoxia, resulting in greater blood flow and, consequently, greater capillary pressures. On the other hand, HAPE may be due to general vasoconstriction in the pulmonary circulation (normally a response to regional ventilation-perfusion mismatches) which, with constant or increased cardiac output, also leads to increases in capillary pressures. For those suffering HACE, dexamethasone may provide temporary relief from symptoms in order to keep descending under their own power. HAPE can progress rapidly and is often fatal. Symptoms include fatigue, severe dyspnea at rest, and cough that is initially dry but may progress to produce pink, frothy sputum. Descent to lower<unk> s alleviates the symptoms of HAPE. HACE is a life-threatening condition that can lead to coma or death. Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower<unk> s may save those afflicted with HACE.
Altitude sickness
Hangover
Sweating sickness
Dehydration
Motion sickness
Fatigue
Chronic mountain sickness
Carbon monoxide poisoning