How to prepare for high altitudes

Pounding headache, nausea, feeling too fatigued to walk more than a dozen steps. Big party last night? I wish. Yesterday, I had driven up the long winding mountain road to the trailhead, parked my car, then hiked up to a lodge situated at 12,500 feet above sea level.

I had not had anything to drink last night, but woke up this morning with all the symptoms of altitude sickness. Unfortunately, I knew this feeling all too well, having experienced similar symptoms in the Andes, Himalaya, and too many times to count in California. Sometimes I got sick in the name of science while at Stanford researching high altitude illness. Often, it was from me heading uphill with a bit too much enthusiasm. 

Throughout my career in wilderness and emergency medicine, I’ve seen plenty of things-gone-wrong at high elevations. The higher you go in the mountains, the more cautious and aware you should be of the risks that come with these new heights. Whether you’re tackling a 14er or are going on a family ski trip, just knowing some basic fundamentals can help you prepare for, avoid, and manage high altitude illness.

The physics

The concentration of oxygen in the air on earth is at a fixed 21% – however, gravity holds most of the earth’s atmosphere and this concentration of air lower to the ground. So as you gain higher elevation, there is less and less air mass above you (or lower atmospheric pressure). This leads to the air being thinner, with fewer oxygen molecules per unit volume. So for every breath that your body is taking in, you’re getting less oxygen than you normally would at lower elevation.

This can put a strain on our bodies, stressing all its systems just to get enough oxygen. It can start off mild, but can quickly become deadly when early symptoms are not addressed or recognized.

How to prepare before you head to higher elevations

Acclimatize, acclimatize, acclimatize!

If you are planning your first trip to high altitude (or if it’s been a while), the best prevention is to have a slow, gradual ascent rate. This is because gradually increasing your sleeping elevation allows your lungs and body more time to compensate and adjust to the lower inhaled oxygen levels. During this process of acclimatizing, your body is becoming more efficient at delivering oxygen. For best results, budget an extra day at an intermediate altitude before your actual ascent. 

Other preparation tips

It can take up to 12 – 24 hours upon arrival at high altitude before you feel the symptoms. Preparing your body is critical to preventing high altitude sickness.

1. 📱 Check the elevation on GOES. You are more likely to get high altitude sickness at or above 8,000 ft above sea level.
2. 🔄 Know yourself. If you’re ever had altitude sickness, you are 13 times more likely to have it again.
3. 🐢 Pace yourself. We all get excited about a new adventure. If you’re hiking, take your time and ascend slower than you think. When you get to your high altitude destination, don’t overexert yourself the first day.
4. 🗓️ Build in time to your travel plans. Instead of heading directly to your destination, do an overnight at a nearby town or place that is lower in elevation to acclimatize. (For example, spending a night in Denver before heading higher to a Colorado mountain resort.)
5. 💊 Request an RX. Prescription medications to prevent and manage high altitude illnesses are available. These can be especially helpful if you are a higher risk individual who has had altitude illness before or don’t have the time to acclimatize to the new environment. Talk to your doctor if this is a viable option for you.

What to pack

• Ibuprofen taken on the day of ascent can help decrease Acute Mountain Sickness (AMS) rates by over 25% (600 mg taken 3 times a day).
• For those with a history of AMS, getting a prescription for acetazolamide (125 mg taken 2 times a day) can help with acclimatization.
• Caffeine can also help treat your high altitude headache.

What can happen to you at higher altitudes

Your body’s response

Quick science lesson: The oxygen you inhale binds to your red blood cells. Blood gets pumped throughout your body to deliver this oxygen to each of your organs.

Remember, the atmosphere is thinner with less oxygen per breath at higher altitudes. In these lower oxygen levels, your body responds by pumping more blood to your brain and lungs to get enough oxygen. The impact and stress put on your body under these new conditions can result in a range of high altitude illnesses, which can be mild to severe.

Mild and common

A common condition of being in higher elevations is Acute Mountain Sickness (AMS). Maybe you’ve experienced some of these symptoms before:

• Pounding or “ice pick”-like headache
• Nausea
• Loss of appetite
• Dizziness
• Fatigue

While AMS is not life-threatening, the symptoms can keep you from feeling like your best self and ruin even the most well-planned mountain adventure.

Those with a less efficient ventilatory response (or those who work harder at breathing in lower oxygen) are almost seven times more likely to get AMS. Unfortunately this is not something you can train for, it appears to be something you are born with or without. 

Common misconception: Being dehydrated does not cause AMS. No matter how much water you drink, aggressive hydration will not help you feel better with altitude sickness. 

Severe and dangerous

While symptoms of acute mountain sickness feel similar to a bad hangover, other serious altitude illnesses can be deadly and are considered medical emergencies.

To compensate for the low oxygen levels, your body will increase blood flow, which increases the blood pressure in the vessels. After a couple days of being at high altitude, the vessels can only withstand so much pressure before they begin to leak fluids into the surrounding tissue. When the leaked fluids build up in the brain or lung tissue, it becomes a dangerously concerning condition of High Altitude Cerebral Edema (HACE) or High Altitude Pulmonary Edema (HAPE), respectively.

HAPE is the leading cause of death from altitude illness.

To avoid these severe, life-threatening conditions, it’s important to recognize the symptoms early and take them seriously before they worsen.

When feeling unwell at high altitudes, descend

In all cases, getting to lower elevation to give your body more oxygen is an effective treatment of any type of severe altitude illness. Most people feel better descending as little as 1,600 – 3,300 feet.

If there is an emergency on a mountain, getting to a hospital or specialized clinic with supplemental oxygen and prescription steroids can be lifesaving.

The high mountains are epic and inspiring places full of fun and adventure. Research has found 25% of tourists to mountain resorts may get AMS, but severe altitude illness is rare in North America and shouldn’t scare you away from going on a mountain trip. With a little planning and knowledge about high altitude illnesses, you can save your next trip, or even a life.