The most effective treatment for altitude sickness is descending to a lower elevation. Most people with mild symptoms improve by stopping their ascent, resting, and dropping at least 1,000 feet (300 meters). For moderate or severe cases, descent is urgent and potentially lifesaving. Beyond that core principle, several medications and supportive measures can speed recovery or buy time when immediate descent isn’t possible.
Recognizing What You’re Dealing With
Altitude sickness typically develops within 6 to 12 hours of reaching a new elevation, most commonly above 8,000 feet (2,500 meters). The hallmark symptom is headache. From there, you may also experience nausea, poor appetite, fatigue, weakness, or dizziness. The formal diagnostic system used by researchers scores these four symptoms on a scale from 0 to 3. A total of 3 or more points, with at least some headache, qualifies as acute mountain sickness (AMS). A score of 3 to 5 is considered mild, 6 to 9 moderate, and 10 to 12 severe.
Two dangerous complications can develop if AMS is ignored. High altitude cerebral edema (HACE) involves swelling in the brain, causing confusion, loss of coordination, and altered consciousness. High altitude pulmonary edema (HAPE) fills the lungs with fluid, causing breathlessness at rest, a persistent cough, and extreme fatigue. Both are medical emergencies.
Mild Symptoms: Rest and Simple Remedies
If your symptoms are limited to a mild headache, slight nausea, or general fatigue, you can often manage them without descending. The key is to stop gaining elevation. Stay at your current altitude (or go slightly lower) and rest until you feel better. Drink enough water to stay hydrated, but don’t overdo it. Forcing excessive fluids won’t cure altitude sickness and can cause its own problems.
Over-the-counter pain relievers like ibuprofen or acetaminophen are the first line for altitude headaches. They’re effective for most people and widely available. If your headache doesn’t respond to simple painkillers, or you develop additional symptoms like vomiting or significant dizziness, that’s a sign you need more aggressive treatment.
Symptoms from mild AMS typically resolve within two to three days of resting at a lower altitude. Many people find they can resume climbing after acclimatizing, as long as they ascend gradually.
Acetazolamide: The Go-To Prescription
Acetazolamide is the most commonly prescribed medication for both preventing and treating altitude sickness. It works by changing the acidity of your blood, which stimulates faster and deeper breathing. This helps your body absorb more oxygen and acclimatize more quickly.
For treating active AMS symptoms, the standard dose is 250 mg taken twice a day. Notably, only this specific treatment dose (two 250 mg doses taken 8 hours apart) has been formally studied, though the lower prevention dose has worked anecdotally. For children, the dose is weight-based. Common side effects include tingling in the fingers and toes, increased urination, and a metallic taste when drinking carbonated beverages. These are annoying but harmless. People with sulfa allergies should avoid it.
Acetazolamide doesn’t mask symptoms the way a painkiller might. It actually accelerates the acclimatization process, which makes it particularly useful if you can’t descend right away.
When Symptoms Get Worse: Descent Is the Priority
If you develop worsening headache, repeated vomiting, significant dizziness, or increasing fatigue, descending is the most important thing you can do. Most experts recommend dropping at least 1,000 feet (300 meters), and potentially as much as 3,300 feet (1,000 meters), until symptoms improve. Don’t wait to see if things get better on their own. Altitude illness can progress rapidly, especially overnight.
The goal with any supplemental treatment, whether oxygen or medication, is to support the person during descent or to stabilize them when descent is temporarily impossible due to weather, terrain, or darkness. No medication replaces getting lower.
Supplemental Oxygen
If supplemental oxygen is available, it’s one of the most effective tools for treating all forms of altitude illness. The target is to raise blood oxygen saturation above 90%, which is the threshold recommended across AMS, HACE, and HAPE. Even low-flow oxygen can make a meaningful difference in symptom relief, and it works quickly.
On guided treks in popular high-altitude destinations like Kilimanjaro, Everest Base Camp, or the Andes, expedition teams often carry bottled oxygen for emergencies. If you’re on a self-supported trip at extreme altitude, knowing whether oxygen will be available along your route is worth planning for in advance.
Portable Hyperbaric Bags
A portable hyperbaric chamber (often called a Gamow bag) is essentially an inflatable sleeping-bag-sized chamber that simulates a lower altitude by increasing air pressure around the person inside. The standard version operates at about 2 psi of pressure, which effectively lowers a person’s altitude by roughly 3,000 to 5,000 feet. In one documented case at 12,100 feet (3,700 meters), a patient with moderate AMS was completely symptom-free after just 20 minutes in a portable chamber.
These bags are most useful when descent is impossible, such as during a storm or on technical terrain at night. They’re a temporary measure. Symptoms often return after the person exits the bag, so descent should follow as soon as conditions allow. You’ll find Gamow bags at some mountain huts, expedition base camps, and with organized trekking companies operating at high altitude.
Treating HACE and HAPE
Both of these conditions are life-threatening and require immediate action. The universal first step is descent, as fast as safely possible.
HACE produces confusion, stumbling, and an inability to walk in a straight line. A person with HACE may not recognize how sick they are. If you’re traveling with someone showing these signs, do not leave them alone or let them make decisions about whether to descend. This condition involves brain swelling, and without treatment it can progress to coma and death within 24 hours. Dexamethasone, a powerful steroid that reduces brain inflammation, is the standard medication used to stabilize HACE patients during evacuation. Supplemental oxygen targeting saturation above 90% is given simultaneously when available.
HAPE presents differently. The hallmark is breathlessness that doesn’t improve with rest, sometimes accompanied by a wet cough, gurgling sounds when breathing, and lips or fingernails turning blue. Descent and supplemental oxygen are the primary treatments. For HAPE specifically, a blood pressure medication called nifedipine can lower pressure in the lung’s blood vessels and improve oxygenation. In one study, nifedipine improved oxygenation and cleared fluid from the lungs even in patients who stayed above 13,000 feet and didn’t receive supplemental oxygen. Recovery from HAPE takes longer than from mild AMS. Even after descent, it can take weeks to fully recover, and hospitalization is sometimes necessary.
Prevention That Reduces Your Treatment Needs
The most reliable way to avoid needing treatment is a gradual ascent schedule. Above 10,000 feet (3,000 meters), increase your sleeping altitude by no more than 1,000 to 1,500 feet per day, and build in a rest day every three to four days. This gives your body time to produce more red blood cells and adjust its breathing patterns.
Acetazolamide can also be taken preventively before a rapid ascent, which is useful if your itinerary doesn’t allow a gradual schedule, such as flying directly into a high-altitude city like Cusco (11,150 feet) or La Paz (11,940 feet). Starting the medication the day before arrival gives your body a head start on acclimatization.
Avoid alcohol during your first day or two at altitude. It depresses breathing during sleep, exactly when your body needs to breathe more. Heavy exertion on your first day also increases risk. Plan easy activities for your arrival day and save the hard hiking for after you’ve adjusted.