The single most effective fix for altitude sickness is descending to a lower elevation. Dropping at least 1,000 feet (300 meters) typically brings rapid relief, and most people notice improvement within hours. If descent isn’t immediately possible, a combination of rest, hydration, pain relief, and in some cases medication can manage symptoms until you can get lower.
Recognize What You’re Dealing With
Altitude sickness, or acute mountain sickness (AMS), shows up as a combination of symptoms: headache plus at least one of the following: dizziness, nausea or loss of appetite, and fatigue. The headache is the hallmark. If you have a headache alone, it could be dehydration or exertion. But headache combined with nausea and exhaustion after gaining elevation is almost certainly AMS.
Mild cases involve a nagging headache and general tiredness. Moderate cases bring persistent vomiting, a pounding headache that doesn’t respond to painkillers, and difficulty with coordination. Severe cases can progress to two life-threatening conditions: fluid buildup in the brain (cerebral edema) or fluid in the lungs (pulmonary edema). The difference between mild and dangerous can shift in hours, so paying attention to worsening symptoms matters more than almost anything else.
Descend If Symptoms Are Getting Worse
Descent is the definitive treatment. Most experts recommend dropping at least 1,000 feet (300 meters), and sometimes as much as 3,300 feet (1,000 meters), depending on severity. The key is to keep going down until you feel noticeably better. Minimize physical exertion on the way down if possible, since heavy effort makes symptoms worse.
If you’re on a multi-day trek and symptoms are mild, stopping your ascent and staying at your current elevation for a day or two often allows your body to catch up. This is called acclimatization rest. But there’s a hard rule here: never continue climbing with active symptoms. AMS that worsens with continued ascent can become dangerous fast. If a rest day doesn’t bring clear improvement, go down.
Treat Mild Symptoms on the Mountain
For a mild case where you’re uncomfortable but functional, several things help while your body adjusts:
- Pain relief: Ibuprofen (600 mg, three times daily) can reduce altitude headaches and overall symptom severity. One study found it performed nearly as well as the prescription medication acetazolamide for managing symptoms, though it was slightly less effective at preventing AMS during rapid ascent. Standard doses of ibuprofen or acetaminophen are a reasonable first step for headache.
- Hydration: The air at altitude is drier and you lose water faster through breathing. Drink enough to keep your urine light-colored, but don’t overdo it. Excessive water intake without electrolytes can cause its own problems.
- Carbohydrate-rich food: Eating a diet where at least 60% of your calories come from carbohydrates (roughly 6 to 8 grams per kilogram of body weight per day) improves how efficiently your body uses oxygen. Carbs shift your metabolism in a way that increases the oxygen levels in your blood compared to relying on fats for fuel. Think rice, pasta, bread, oatmeal, and fruit.
- Rest: Avoid strenuous activity. Your body is already working hard to adjust to lower oxygen levels. Give it the chance to do that without the added demand of a heavy pack or a steep climb.
Acetazolamide for Faster Recovery
Acetazolamide (sold as Diamox) is the most commonly prescribed medication for both preventing and treating altitude sickness. It works by changing the acidity of your blood, which tricks your body into breathing faster and deeper. That means more oxygen in, more carbon dioxide out, and faster acclimatization.
For prevention, it’s typically started the day before ascent. For treatment, it speeds recovery once symptoms have already started. You’ll need a prescription, so if you’re planning a trip to high elevation, talk with a provider beforehand. The most common side effect is tingling in your fingers and toes, and it makes carbonated drinks taste flat. It also acts as a mild diuretic, so you’ll need to drink more water while taking it.
When Altitude Sickness Becomes an Emergency
Two complications turn altitude sickness from miserable to life-threatening. Both require immediate descent and emergency medical care.
High-Altitude Cerebral Edema (HACE)
This is swelling in the brain. The warning signs are confusion, loss of coordination (the person can’t walk a straight line), and changes in behavior or consciousness. HACE can kill within 24 hours if untreated. Immediate descent is critical. In expedition settings where descent is delayed, dexamethasone (a powerful steroid) is used as a bridge treatment to reduce brain swelling, but it’s not a substitute for getting lower.
High-Altitude Pulmonary Edema (HAPE)
This is fluid filling the lungs. It typically shows up as breathlessness at rest, a persistent cough (sometimes producing pink or frothy spit), and extreme fatigue. HAPE usually develops on the second or third night at a new altitude. Descent and supplemental oxygen are the primary treatments. Nifedipine, a blood pressure medication that reduces pressure in the lung’s blood vessels, is used in the field when descent is delayed.
Both HACE and HAPE can develop even in fit, experienced climbers. Physical fitness does not protect against altitude illness. The primary risk factor is how fast you ascend relative to how much time your body has had to adjust.
Preventing Altitude Sickness in the First Place
The best fix is avoiding the problem entirely. Most altitude sickness comes from ascending too fast.
Above 9,000 feet (2,750 meters), the standard recommendation is to increase your sleeping elevation by no more than 1,000 to 1,500 feet per day. Every 3,000 feet of elevation gain, build in a rest day where you sleep at the same altitude as the night before. The climbing adage “climb high, sleep low” works well: you can hike to a higher point during the day as long as you return to a lower camp to sleep.
If you’re flying directly into a high-altitude city like Cusco (11,150 feet), La Paz (11,975 feet), or Lhasa (11,450 feet), expect some degree of AMS. Plan a low-activity first day or two. Acetazolamide taken preventively before arrival significantly reduces the odds and severity of symptoms in these situations.
Alcohol worsens symptoms and impairs your body’s ability to acclimatize. Skip it for at least the first 48 hours at a new altitude. Sleeping pills and sedatives can also suppress your breathing rate at night, exactly when your body most needs to compensate for thin air.
What Recovery Looks Like
Mild AMS typically resolves within 12 to 24 hours after you stop ascending, either by resting at your current altitude or descending. Moderate cases improve rapidly with descent, often within hours of reaching lower ground. After recovery from a mild or moderate episode, you can usually resume climbing, but do so more gradually and with built-in rest days.
Recovery from HAPE or HACE takes longer. Even after descent, residual fatigue and headache can linger for days. Anyone who has experienced either condition should not re-ascend on that trip without medical clearance, and should plan future high-altitude trips with extra caution and possibly preventive medication.