Whether on foot, skis, or tires, there’s nothing like the beauty and exhilaration of high-altitude treks. The awe-inspiring views, the crisp, clean air, the experience of an alpine excursion lasts a lifetime. But the higher you plan to scale, the more you need to take extra precautions to deal with the potentially dangerous effects of high altitude.

What Is Altitude Sickness?

Altitude sickness, also known as Acute Mountain Sickness, describes several symptoms that happen when your body is unable to adapt to a low-oxygen, low-pressure environment—typically at about 8,000 feet above sea level. These symptoms can range from mild to life-threatening. The good thing is that by taking proper steps before and during the trip, you can help stave off these effects. Here are some tips to stay safe on your next big-mountain epic.

Train

Even the fittest person on Earth can get hit with altitude sickness, but being healthy certainly helps most people. The best way to prepare your body for high altitude is to get your cardiopulmonary system in shape. Running, cycling, and swimming are ideal. If possible, work out at a higher elevation, then return to a lower altitude to sleep (“train high/sleep low”). Remember, you’ll be going up, so start engaging those calves and glutes before you hit the high altitudes. Start walking at a brisk pace, find a steep hill and climb up it regularly. Run a few times a week. If hills are hard to come by, strap on the backpack, add some weight, and take the stairs. A little effort now will make your trip at altitude easier.

Drink Lots of Water

It’s easy to lose track of your hydration level at high altitudes. The air is dry and cool, which means sweat leaves your body faster and less noticeably. Start hydrating before your trip and keep hydrating when you are at altitude. Don’t wait until you’re thirsty. You should limit caffeine and alcohol as well, as they can contribute to dehydration. People often don’t sleep well the first couple of nights, and caffeine will only make that worse. Also, be cautious when it comes to alcohol as its effects will be more pronounced at altitude.

Fuel Up

The human body burns more calories even at rest when high up. Carbs are your friend here, so pack plenty of whole-grain snacks. Foods high in potassium such as bananas, bran, chocolate, granola, dates, and dried fruit will help you replenish electrolytes by balancing salt intake.

Take It Slow

No need to run for the hills as soon as you get off the plane. Give yourself a day or two of local sightseeing so the body can acclimate, and then when you do climb, take it slow. Climb at a pace that’s comfortable for you and take frequent rests. Aspirin and Ibuprofen can help with the headaches that can happen the first couple of days at altitude.

Know the Signs

Familiarize yourself with what altitude sickness looks like, and be prepared to take action if you or members of your team experience these symptoms. Remember that when the symptoms are apparent, the only cure is to descend to a lower altitude immediately. Don’t “take a quick break” and try to shake it off; things won’t get better.
Dr. David Shlim is the Medical Director of the CIWEC Clinic Travel Medicine Center in Kathmandu, Nepal, and he knows a few things about altitude. These are his Golden Rules:

1. If you feel unwell, you have altitude sickness until proven otherwise.
2. Do not ascend further if you have symptoms of altitude sickness.
3. If you are getting worse, then descend immediately

Mild symptoms include:
• Headache
• Nausea
• Dizziness
• Feeling tired
• Shortness of breath
• Faster heart rate
• Not feeling well overall
• Trouble sleeping
• Loss of appetite
These symptoms go away on their own when you move to a lower altitude, and if they’re gone, you can start the trip again after a couple days of rest. Severe symptoms include:
• More intense versions of the mild symptoms
• Feeling out of breath, even when you’re resting
• Coughing that won’t stop
• Tightness or congestion in the chest
• Trouble walking
• Seeing double
• Confusion
• Skin color changing to gray, blue, or paler than normal
It is never normal to feel breathless when you are resting—even on the summit of Everest. So, if you notice any of these symptoms, get to a lower altitude as soon as possible and seek medical attention. Severe altitude sickness can cause fluid in the lungs and brain, which can lead to death.

Know Your Limits

If you have any existing medical conditions, like heart problems, trouble breathing, or diabetes, talk to your doctor before traveling to high altitude. Be prepared to turn back if you feel discomfort. A mountain trail is no place to test your body’s ability to self-correct. The summit will always be there—don’t be a hero.
Seeing the first light just barely touch the tops of craggy peaks or snowy summits is something you’ll never forget and is worth every effort that you put in. Remember: drink water, wear sunscreen, and don’t be in a hurry! Altitude sickness is no joke, but with a little preparation and alertness, there’s no reason you can’t enjoy every minute of your alpine adventure.

What to Wear at Altitude

The thing that you need to know about the weather at altitude is that it’s very unpredictable. Even if the forecast looks beautiful, it can quickly change when you’re on the mountain. So be prepared for anything. Dress in layers to help you adjust as the temperature gets warmer or colder. Look for clothing that uses 37.5 Technology, a fabric technology that helps regulate the body’s temperature and humidity levels, making it perfect for travel wear and outdoor clothing where conditions change continually. For a base layer, consider something like the Fourlaps Level Tee or Salomon S/Lab NSO Tee which will keep you comfortable close to the skin even if you need to layer up. For that outer layer, consider a waterproof jacket from Original Mountain Marathon or Dahlie. There’s enough difficulty at altitude without worrying about your clothes—make sure you have everything you need no matter what weather comes along.
Written by Shaine Smith for Matcha in partnership with 37.5.