Altitude Sickness Symptoms & Prevention

In June, I attempted to hike to Kearsarge Pass at 11,709 feet in the Eastern Sierra’s. The trail is five miles one way. I was going to summit, then camp at one of the lakes on the way down along the trail. I left the Central Coast in California (sea level) at 2:00am and drove up on two hours of sleep. I arrived at the trailhead around 6:30am and started hiking, without giving myself proper rest and time to acclimate. At the time, this seemed like a good idea.


I didn’t make it. I was getting dizzy, exhausted, and nauseous about a mile from the top. It also took about 12 hours just to hike four miles, so I decided to set up camp at 10,800 feet and summit in the morning. But after an hour of sleeping, I woke up with my head pounding, and no amount of Advil that I was taking was helping. I tried to sleep for another two hours, telling myself I was just exhausted. But I felt like throwing up, I was dizzy, and my entire body was saying get off this mountain. So, I woke up my hiking buddy at 9:30pm, packed up camp and hiked down.


On a longer hike at higher altitude, this situation could have been worse. Reading this it’s easy to think, that’s a dumb idea, why would you do that? I know, but in the moment these things seem like good ideas.


Learn from my mistakes with altitude and listen to your body. Your safety is more important than finishing the hike. It’s ok to stop and to turn around if it means you will safely get back, the mountains will still be there.


Whether you’re hiking your first 14’er, going on a ski-cation, or just curious, in this blog post I’ll cover symptoms and how to prevent altitude sickness.


Give yourself time to acclimate

Acclimating can take several days, especially if you are coming from sea level to a destination above 8,000 feet. Spend the first day at the trailhead (or other nearby location at altitude), acclimate, get a good night’s rest and then begin your trek. Plan your trip so once you’re above 8,000 feet, you only ascend 1,000 feet daily. If your itinerary doesn’t allow this, then climb higher during the day and sleep lower, especially for the first few days.


Take it easy, especially at first

As you’re hiking up, take breaks along the way, pace yourself, and take it fairly easy. Hiking (especially long distance at altitude hikes) is a strenuous sport, and your physical performance is always reduced at higher altitudes because of your body’s decreasing ability to take in oxygen.



Dehydration can affect the body’s ability to acclimate. Reduce your alcohol intake a week prior to traveling to altitude and start drinking 65-100 oz of water per day the week prior to your trip. During your trip, sip water often to keep yourself hydrated.


Listen to your body

If you’re in a similar situation as me, and your body is saying I’ve had enough, I need to get down. Get down. That is the best solution for altitude sickness, to get lower elevations. Your safety is more important than finishing the hike. The mountain will still be there. This doesn’t mean you can’t ever hike at altitude, this means you need to take precautions such as taking more time to acclimate or medication to get you there next time.

Symptoms of Altitude Sickness

Minor Symptoms to watch for

If you are feeling any of these, do not continue further up. Let your body acclimate.

  • Dizziness
  • Nausea or vomiting
  • Feeling weak and exhausted
  • Insomnia and feeling sleepy


Major Symptoms to watch for

If you’re feeling any of these, do not continue further. Turn around and descend to a lower elevation. It can cause fluid in the lungs and swelling of the brain. It can kill you.

  • Persistent dry cough
  • Fever
  • Panting even while resting
  • Headache that is not reducing with pain killers
  • Increased vomiting
  • Increased dizziness


Final thoughts

Altitude sickness is not something to be taken lightly. It can lead to death, so make sure you acclimate. Everyone’s body reacts differently in altitude. Personally, with a full night’s rest, I’m typically alright up to 12,000 feet after coming up from sea level. It’s at 12,000 feet that my body really starts slowing down and if I don’t acclimate, I start to get dizzy. I know my body so it allows me to plan trips accordingly so I know how long I need to acclimate.


But everyone is different. I’ve hiked with hardcore hikers that start to feel the altitude and possibly even get altitude sickness at 7,000 feet or 10,000 feet. Before trying to summit a 14er, start with 7,000 feet, then 10,000 feet, then 12,000 feet, and work your way up. Listen to your body and learn about your body. So when you do summit a 14er, you know roughly how long you need to acclimate and what helps you.


Training helps your heart pump more blood and your muscles use oxygen more efficiently, but nothing substitutes for giving yourself time to acclimate.


  • Kate

    August 1, 2018

    This was really helpful! Thanks on the advice!

  • George Vasquez

    August 16, 2018

    Thanks for that information. Extremely valuable for the novice hiker like me

  • Joe Gustaff

    December 1, 2018

    Hi Jenny – My daughter and I were hiking over Mather Pass 2 summers ago and she got altitude sickness about 1000 feet from the summit – We camped at about 10800 feet that night (which was risky) and when she didn’t feel better we immediately descended and she was fine – The next year we did the same hike exiting out of Kearsarge but took Diamox before going and 2-3 days in – we also slowed our pace and made more reasonable hiking goals – Had a wonderful 6 day hike from Bishop Pass to Kearsarge – This summer we plan on finishing the JMT which we have been section hiking – Your altitude sickness warnings are very appropriate for the Sierra – Loved the HST journal


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