<unk> , the mildest form being acute mountain<unk>  (AMS), is the harmful effect of high<unk> , caused by rapid exposure to low amounts of oxygen at high elevation. People can respond to high<unk>  in different ways. Symptoms may include headaches, vomiting, tiredness, confusion, trouble sleeping, and dizziness. Acute mountain<unk>  can progress to high<unk>  pulmonary edema (HAPE) with associated shortness of breath or high<unk>  cerebral edema (HACE) with associated confusion. Chronic mountain<unk>  may occur after long-term exposure to high<unk> .<unk>  typically occurs only above , though some are affected at lower<unk> s. Risk factors include a prior episode of<unk> , a high degree of activity, and a rapid increase in elevation. Diagnosis is based on symptoms and is supported in those who have more than a minor reduction in activities. It is recommended that at high<unk>  any symptoms of headache, nausea, shortness of breath, or vomiting be assumed to be<unk> . Prevention is by gradually increasing elevation by no more than per day. Being physically fit does not decrease the risk. Treatment is generally by descending and sufficient fluids. Mild cases may be helped by ibuprofen, acetazolamide, or dexamethasone. Severe cases may benefit from oxygen therapy and a portable hyperbaric bag may be used if descent is not possible. Treatment efforts, however, have not been well studied. AMS occurs in about 20% of people after rapidly going to and 40% of people going to . While AMS and HACE occurs equally frequently in males and females, HAPE occurs more often in males. The earliest description of<unk>  is attributed to a Chinese text from around 30 BCE which describes "Big Headache Mountains", possibly referring to the Karakoram Mountains around Kilik Pass.
Altitude sickness
Hangover
Sweating sickness
Dehydration
Motion sickness
Fatigue
Chronic mountain sickness
Carbon monoxide poisoning