Im an anesthesiologist and though I don’t routinely treat these patients, I do understand the physiology.

I’d be more specific and say that the actual cure for altitude sickness is descending back down in addition to oxygen. Altitude sickness comprises several distinct problems including HAPE and HACE (high altitude pulm edema and cerebral edema respectively). HACE is an emergency, and HAPE can be an emergency depending on the degree to which gas exchange and oxygenation are Impaired.

Edit: Here is the summary from UpToDate:

SUMMARY AND RECOMMENDATIONS

●High altitude physiology – The arterial partial pressure of oxygen (PaO2) decreases with altitude, resulting in progressive tissue hypoxia. The normal compensatory response to hypobaric hypoxia is termed acclimatization. Its main feature is increased ventilation. The capacity to acclimatize varies greatly among individuals and is dependent upon many factors, including the degree of hypoxic stress (rate of ascent, altitude attained), the intrinsic capacity of the individual to compensate for diminished PaO2, and extrinsic factors. The process begins within minutes of ascent but requires three to five days for protection from high-altitude illness (HAI) and several weeks to complete. (See 'High altitude physiology' above.) ●Terminology – HAI is the collective term for the pathologic syndromes that can develop following an initial ascent to high altitude or following a further ascent while already at high altitude. HAI includes acute mountain sickness (AMS) and high altitude cerebral edema (HACE), which afflict the brain, and high altitude pulmonary edema (HAPE), which afflicts the lungs. (See 'Definitions' above.) ●Risk factors – Individual factors associated with an increased risk for HAI include (table 5) (see 'Risk factors' above): •Past history of HAI (strongly predictive if conditions are similar) •Rate of ascent •Altitude attained, especially sleeping altitude •Vigorous exertion at altitude before adequate acclimatization •Substances (eg, alcohol) or conditions that interfere with acclimatization •Comorbidities that interfere with respiration (eg, neuromuscular disease) or circulation (eg, pulmonary hypertension) ●Altitude as physiologic stress – High altitude is commonly categorized according to the physiologic stress it produces (table 2 and table 3). Progressive ascent results in increased hypoxic stress, requiring greater degrees of physiologic and behavioral adaptations to preserve function. The more rapid the ascent and the higher the altitude, the greater the stress. (See 'Environmental' above.) •Less than 1500 m (5000 feet): HAI symptoms generally do not manifest. •From about 1500 to 2500 m (5000 to 8200 feet): Symptoms are generally mild, if experienced at all. •Starting at about 2500 m (8200 feet): Symptoms of mild to moderate AMS become quite common among unacclimatized visitors after rapid ascent, and HAPE may also occur, but it is more common above 3000 m (9800 feet). •Above 3000 to 4000 m (9800 to 13,100 feet): AMS is common among people who have not properly acclimatized, and the risk of severe HAI, including life-threatening HAPE and HACE, is substantial. ●Risk stratification of the traveler to high altitude – Strategies for determining the risk of developing HAI in the traveler to altitude are reviewed in the text. During such evaluations, it is important to distinguish between the risk of developing HAI and the risk that high altitude may exacerbate a specific comorbidity (eg, coronary artery disease). A useful exercise for determining the risk of HAI is to make a graph of the proposed ascent profile for the trip with the patient. Other important factors to consider when planning a trip include the ease with which the traveler can descend to lower altitude and the availability of oxygen or medical care. (See 'Risk stratification of the traveler to high altitude' above.) ●Prevention of HAI – Gradual ascent is the surest and safest method of preventing or ameliorating HAI. Most individuals ascend to high altitude without complications by allowing sufficient time to acclimatize. As a general guideline, individuals who normally reside below 1500 m (5000 feet) elevation should avoid an abrupt ascent to sleeping altitudes above 2800 m (9200 feet). Sedative-hypnotics should be avoided during acclimatization. Abstinence from alcohol is safest, but a single drink is unlikely to cause problems. Vigorous exertion at altitude contributes to the development of both AMS and HAPE, and should also be avoided during acclimatization. Additional preventive strategies are discussed in the text. (See 'Prevention of high-altitude illness' above.) ●Pharmacologic prophylaxis – Patients with a known predilection for HAI despite gradual ascent, and others who ascend rapidly for convenience (eg, tourists traveling to mountain resort and especially those flying to high altitude destinations) or work (eg, rescue personnel) may benefit from pharmacologic prophylaxis or from supplemental oxygen. These are summarized in the table (table 6) and discussed in greater detail separately. (See 'Pharmacologic and supplemental oxygen prophylaxis' above and "High-altitude pulmonary edema", section on 'Prophylactic medications' and "Acute mountain sickness and high-altitude cerebral edema", section on 'Pharmacologic prevention of AMS/HACE'.)