Trail First Aid: Altitude Illness

A totally realistic ultrarunning scenario:

Your buddy finally got selected in the lottery to run the Hardrock 100 after six years of trying, and he asked you to crew and pace him. He’s spent the last month up in the San Juan Mountains of Colorado running sections of the course and acclimatizing. The Hardrock course ranges in altitude between 7,700 feet and 14,000 feet, and the runners spend the majority of their time around 11,000 feet.

The Hardrock 100 clockwise course profile. Image is a screenshot from the event’s Runner’s Manual.

There’s no simulating that in San Antonio, Texas (elevation 650 feet) where you both live. You’d planned to drive up the week before Hardrock, but with one thing and another, you don’t make it to Silverton, Colorado (9,318 feet) until the day before the run. You don’t sleep well that night, and when you get up to see the runners start, you have a rotten headache. You don’t feel much like eating breakfast with the rest of the crew. You just feel beat. Honestly, if you’d had more than one beer last night, you’d chalk these symptoms up to a hangover.

You should:

A. Take an ibuprofen
B. Drink some water
C. Suck it up and pack the crew vehicle
D. Drive down to the city of Durango (elevation 6,522 feet)
E. Go to a higher elevation

Choose an answer before continuing.


A. Take an ibuprofen

A headache is the defining symptom of mild and moderate altitude illness, also known as Acute Mountain Sickness (AMS). The headache can range in severity from 1 to 10 on a pain scale–from “Not Tonight Honey” to “Ice Cream Headache.” Taking an over-the-counter pain medication might provide a little relief. Take the dose recommended on the packaging.

B. Drink some water

Water will not make your altitude-induced headache go away, but it’s easy to become dehydrated at altitude, so go ahead and drink up. There’s no use being dehydrated and having altitude illness. (For the record, a headache is not a common sign of dehydration.)

C. Suck it up and pack the crew vehicle

These are the symptoms of mild and moderate altitude illness:

  • Headache (in addition to one or more of the other listed symptoms)
  • Nausea with possible vomiting
  • Loss of appetite
  • Fatigue or weakness at rest
  • Insomnia

They usually improve or resolve within 48 hours (if you don’t go any higher). If you aren’t short of breath while you’re sitting still, or having trouble with coordinated movements (like walking), and you’re not confused or disoriented, then light exercise like packing the car will help with acclimatization.

D. Drive down to the city of Durango (elevation 6,522 feet)

This would alleviate the headache and other hangover-like symptoms. A decrease in elevation of 2,000 feet will usually diminish or relieve symptoms depending on the altitude you started from. Most people don’t have signs and symptoms of altitude illness below 8,000 feet.

E. Go to a higher elevation

This will make your symptoms worse. You feel awful because there are decreased levels of oxygen in your blood due to the decreased atmospheric pressure at altitude. If you go higher, your oxygen levels will drop further, and you will feel even worse.

So the only way to alleviate your headache and other symptoms is to get rid of the altitude. But in this particular scenario, that’s a pretty lame choice. Your symptoms are mild and sucking it up and crewing your friend is a good answer. Taking an ibuprofen for your headache is also a good answer. Staying hydrated is another good answer. (What kind of crappy multiple-choice test is this?) Really, the only bad answer is “Go higher.”

Of course, you are planning to go higher today, and so the scenario continues.

You’re pacing your buddy about 20 miles between the Sherman and Cunningham Gulch aid stations.

A modified Hardrock 100 clockwise course profile showing this scenario. Image is modified from a screenshot from the event’s Runner’s Manual.

You’ll climb and stay above 12,000 for a good chunk of this section. By the time you make it to Maggie Gulch aid station, located midway through your pacing gig, your headache is so bad that you can’t think about anything else. It feels like your forehead is in a carpenter’s vice and every time you turn, it’s like your brain is crashing into your skull. You’ve been vomiting for the last half hour and have to work hard to keep up with your friend’s hiking pace. From Maggie Gulch, you’ll climb above 13,000 feet to Buffalo Boy Ridge before dropping down to Cunningham Gulch aid station.

Should you continue on?

A. Yes
B. No

Choose an answer before reading further. Justify your answer.


B. No

You are suffering moderate altitude illness. If you go higher, your symptoms will probably get worse. You are no help to your runner. In fact, in this mountain environment, you are a safety hazard.

But you choose “A.” There’s no way your runner is going to drop you. You’d never hear the end of it. And thus the scenario continues.

You make it over Buffalo Boy Ridge right before a thunderstorm rolls in and lightning traps you and your runner around 12,500 feet. You hunker down behind a rock for almost an hour before it’s safe to move again. By that time, you’ve started to cough. It’s a dry cough. And once you start moving, you can’t keep up with your friend. You lag behind, stopping often to catch your breath. You tell him you just need to sit down for a minute. You’re still having trouble catching your breath as you sit there. You cough some more.

What do you do?

A. Find a safe way to descend NOW
B. Keep going, as it’s only about three miles to the next aid station

Choose an answer before reading further.


A. Find a safe way to descend NOW

You have High Altitude Pulmonary Edema (HAPE). Fluid is accumulating in your lungs. This kind of severe altitude illness can kill you. Symptoms include:

  • Decreased ability to exercise
  • Persistent dry cough
  • Shortness of breath at rest
  • Increase heart rate and respiratory rate at rest
  • Pale or bluish-colored skin
  • A productive cough (late sign)

There are three things you can do to treat HAPE:

  1. Descend
  2. Get down
  3. Go lower


If emergency medical services are necessary, they will also administer oxygen.

Finally, the scenario ends. Your friend learned about the dangers of HAPE during a Wilderness First Aid course. He insists you take an old mining road that leads off the mountain and down to the aid station immediately, a shortcut off the course that allows you to descend faster. He runs ahead to see if he can get an ATV to come up the road and meet you. He knows this will mean he’ll miss the time cutoff at Cunningham Gulch. You take the ATV ride to the aid station and then a car ride down to Montrose (5,807 feet).

By the time you reach town, your headache is gone and so is the nausea. You spend the night, and by the following afternoon, you’re no longer coughing or short of breath while you’re just sitting around. If only your ego had been smaller, and you hadn’t kept going higher despite your symptoms of moderate altitude sickness, your friend might be a Hardrock finisher. Oh well, he’ll get back in someday. Maybe. You know how that lottery is. You start your drive back home feeling fine and thinking about the acclimation recommendations in Corinne Malcolm’s iRunFar article Into Thin Air: The Science of Altitude Acclimation.

[Author’s Note: Learn more about mild, moderate, and severe altitude illness and how to prevent it and other wilderness first-aid skills with a two-day NOLS course. Thank you to Tod Schimelpfenig, NOLS Wilderness Medicine’s Curriculum Director and author of NOLS Wilderness Medicine, for his guidance and oversight of this series. Thanks also to graphic artist Brendan Leonard, the trail and ultrarunner of Semi-Rad fame, for his graphics collaboration in this article series.]

Call for Comments

  • Have you ever experienced symptoms of altitude illness while trail running or ultrarunning? What did you do to alleviate them and did the symptoms improve?
  • Have you ever developed severe altitude illness while running? What was the situation and how did you resolve it?
Liza Howard

is a longtime ultrarunner who lives in San Antonio, Texas. She teaches for NOLS Wilderness Medicine, coaches, directs the non-profit Band of Runners, and drives her kids around in a minivan.

There are 44 comments

  1. Chris R.

    Very entertaining report. Great advice about how we shouldn’t let our ego get in the way of doing the sensible thing as a pacer. At a race like Hardrock it is fairly likely the runner will be better acclimatized than the pacer.

  2. Raymond Wright

    Nice article. Thank you. I am “running” the Sun Valley Cirque Series race in 10 days. It starts at 5,894 ft with the summit at 9,150. Total vert 3,955. The race is only 9.4 miles. I live at sea level and have not been able to train at altitude at all. I’ll be in the area, but at lower altitude (3,000 ft) for 4 days prior to race day but could get some time at altitude.

    Since during the race I am at altitude for such short period of time is there anything to worry about altitude sickness wise?

    1. Liza

      Raymond, If you can get up higher during those 4 days prior to the start, you’ll likely feel better during the race itself. I mean, that climb will be hard regardless! It’s totally possible you could suffer mild altitude sickness symptoms (headache and hangover-ish), but like you said, it won’t be for very long — and the treatment in your case will be getting to the finish line back at 5894 ft. Good luck!!

    2. Markus

      while you will feel some effects of running with less oxygen, I wouldn’t think that this could cause any altitude sickness at 9150 ft.

    3. Josh

      I’ve been in Sun Valley for the past 6 months doing a bulk of my clinical rotations as a third year medical student. We commonly see mild symptoms of altitude sickness such as headache, shortness of breath, and nausea in patients who ascend from sea level. If you have a history of altitude sickness, I would certainly talk to a physician about a medication. Generally, medication isn’t recommended until you ascend over 9200 feet (Baldy is just under that). It is encouraging that you will get to spend a few days at a higher elevation before the race. I would avoid alcohol for at least 24 hours before the race. Some studies have shown good hydration and taking in carbohydrates during an athletic event at high altitudes can prevent minor symptoms of altitude sickness. In other words, drink enough water and pound a gel as you make your attack on the summit. Chances are, you’re probably going to be fine. If not, we have a fantastic hospital in Ketchum. I’ll be “running” the race as well so maybe I will see you out there. Best of luck to you my friend!

  3. Rob

    I’ve finished Hardrock five times coming from the lofty highlands (~600ft) of Northern Alabama. Three of those finishes (2 x CCW, 1 CW) I just showing up at the last minute to make race check-in. For me my experience was almost the reverse of your figure; especially for my two CCW finishes that put you up high on the Continental Divide relatively early into the race. Most recently, in 2015, I was very slow through that stretch, slight headache and just a bit nauseous; nothing debilitating or scary just enough to be very uncomfortable. But after popping some ibuprofin at Sherman and just continuing to plug along, slowly, I did gradually begin to feel better. At Grouse Gulch I was looking at a 44 hr finish, but I was able to speed up remarkably over the second half and finished in just over 37 hours; a PB for running Hardrock unacclimated. I think but for that stretch on the Continental Divide Hardrock would be significantly easier for those prone to altitude sickness as the course generally yo-yos up and down enough that by the time you start feeling bad (for me, above treeline or ~11,500′) you hit a pass or peak and start descending once again and feel better.

    Coming from Alabama I’ve found that just training in the extreme heat and humidity probably have helped me quite a bit with dealing with altitude. I just try and get in the best shape I can going in and train specifically at the hottest parts of the day and show up to the race with low expectations and just take it easy. Granted, I’ve finished A LOT faster when I was able to come out at least two weeks early, but often that’s not possible for me.

  4. Mike Miller

    I think people who live at altitude tend to underestimate the effects on those who are not used to altitude. I’ve lived at relatively high elevation most of my adult life and never gave it much thought other than dealing with an occasional headache.

    But the potential for mild altitude sickness to progress into HAPE is real and devastating. About 15 years ago I spent a winter following lynx around on skis at elevations of 10-12k in Colorado. That summer I spent building my house outside Durango at 8,000 and recreating at much higher elevation. I was pretty well acclimated. But in the fall I started grad school in Indiana and after 3 months at low elevation I returned to Colorado for christmas. I went straight to Leadville to meet some friends for a hut-trip and after the first night at 12k I started getting the symptoms of altitude sickness. I considered going back down but my friends talked me out of it and I decided to see how it went. Of course by afternoon I realized it was getting worse but by then it was too late for me to leave by myself. After a very rough night I realized I was into the early stages of HAPE with fluid in my lungs. I left as soon as the sun came up and my friends were still trying to talk me into staying but I knew exactly what was happening. It was a little intimidating to ski out solo in mid-winter in my condition. I was so weak at one point that I went into a tele-position to make a turn in the trail and couldn’t stand back up again. Fortunately it was all downhill and not very steep so I was able to get back to my car but there is no doubt in my mind that if there had been any climbing involved I would have been too weak to get out on my own and since it was mid-winter in a remote part of the Colorado Rockies I probably would have died. And this was something that the previous winter I did every day for work, I was no rookie.

    I had a similar experience this past winter while training for a climb of Pico Orizaba, a 18,500 ft. volcano in Mexico. Even though I live over 7k in Mexico City and was acclimating by sleeping at 10k and climbing to 13k one day a week and thought I was pretty well acclimated I still had a very bad night in my last week of acclimation before the climb. It began with camping at the trailhead for Ixta at over 13k and climbing almost to 17k. Then the next night I slept at Paso Cortez at 12k and felt pretty good. the third night sleeping at 12k though I started getting headaches and it was too late for me to leave. Things got worse all night and every time I fell asleep I woke up gasping for air. It was pretty terrifying. Fortunately I was able to get to lower elevation in the morning before it progressed to HAPE.

    My point is that its real and it can affect even people who are well acclimated. And HAPE can quickly get to the point where you are pretty close to helpless if you are alone. Everyone responds different to altitude and it has zero to do with fitness. In fact there is some evidence to suggest that trained athletes are more sensitive to elevation than others. You may be OK for one night, or even 2 but that doesn’t mean you’ll be OK the third or 4th night. So be aware, don’t take chances with yourself and especially don’t take chances with others. I think ultra-runners and others used to running through pain and completing a goal no matter what are especially susceptible to altitude effects. We are used to suffering and pushing through rough patches. But HAPE is not a rough patch. There is no pushing through it. Once it starts the only two possible way to survive is to get to lower elevation before its too late.

    Like the saying goes, Everyone wants to get to heaven but nobody wants to die.

    1. Liza

      Thanks so much for posting this, Mike! Amen about the ultra mindset setting people up for failure when it comes to taking action when altitude sickness symptoms get worse.

    2. Markus

      Great points Mike. Even Sherpa’s in the Khumbu Valley get altitude sickness. I forgot what the exact trekking rules are but beyond 11-12000ft you are only supposed to climb so many ft per day (It’s a lot less than you would think.) if you want to sleep there and go higher.

      Also living in high altitude does only help with coping of the effects at that altitude. It does not make it safer if you go much higher very fast and sleep there.

  5. Liza

    Thanks for commenting, Rob! That’s really interesting about your CW and CCW experience. I think your point about keeping lower expectations if you have to show up right before a race is a really important one too. You might get lucky and escape altitude sickness and you might not. A lot of flatlanders (me very much included) have to roll the dice — but I don’t think we often see it as much of a gamble as it is.

  6. Trevor

    thanks for this article. living in san diego, i think about this a lot. besides ‘arrive two weeks early’ to acclimate, are there any other strategies folks can pursue?

  7. Al

    Well written article. I summited Kilimanjaro(19500ft) in 6 days basically coming from sea level. I’ve witnessed all kinds of altitude problems including one very severe case of HAPE which required evecuation.
    I think some people regardless of their age or fitness level are more prone to altitude sicknesses. My advice would be avoid alcohol, drink at least a gallon of water daily and use diamox after talking to your doctor. Obviously if you have time, ascend gradually and try to sleep lower. Speed of ascent plays a major role.Also heat training helps a lot because it increases blood volume.

  8. Liza

    Thanks, Al! Yeah, like you said, it’s not understood why some people suffer and others don’t. I do know the amount of water an individual will need really varies too.

  9. Mike

    Anyone ever encounter symptoms such as hot and cold shakes at the same time at high altitude? I encountered this last year approximately 50 miles into run rabbit run and although the temperature had dropped to ~50 degrees for at least two hours, I was still sweating but also shaking cold at the same time. The aid station volunteers/medics told me this was altitude sickness but I’ve never heard of these symptoms. When I asked them about this, they basically said anything can happen with altitude. No other symptoms such as nausea, headache, fatigue (beyond what is normal 50 miles in) etc.

      1. Mike

        Yes. Fueling and water was fine. It had gotten quite hot earlier in the day but had cooled off significantly for at least a couple hours before this started happening. If I had to guess, it was likely more related to the heat than altitude but the volunteers kept telling me it was altitude sickness.

        1. Liza

          Volunteers are the best, and sometimes they tell you things that aren’t quite right. For example, they usually tell me I look good when I come through the aid station. Also, when I got married in Fort Collins and my entire side of the family felt like they had hangovers, all the locals told them it was altitude sickness, but they were just hungover.

  10. Chris

    Interestingly, I struggle with significant altitude sickness at about 8000 feet when racing but not when hiking. I seem to be able to hike at 12,000-13,000 feet with almost no acclimation and experience only minor issues. Seems that effort, at least for me, plays a huge role.

  11. Liza

    That makes sense, and I think it helps explain why some runners don’t expect to get altitude sickness when they race. I’ve had coaching clients who’ve had similar experiences. “I never had trouble when I go skiing in Colorado.” Thanks for commenting, Chris!

  12. Don

    Thanks. We are doing TransRockies Race (6day) in 2 weeks and coming from VA. A “friend” told me to take Altka Seltzer to help with issues? Thoughts?

    1. Liza

      Hi Don, The aspirin in Alka-Seltzer might help with the altitude headache. I don’t of any studies showing how bicarb would help. Let me talk with our curriculum director and see what I can find out.

    2. Liza

      Don, the Alka Seltzer might also help with the nausea with altitude sickness, but it won’t help with acclimatization. Tod Schimelpfenig says this is a pretty persistent myth with altitude.

  13. Rick

    Is there any relationship between the level of effort and developing HAPE? Wondering if if increased pulmonary blood flow from running as opposed to hiking while at altitude increases the chances of developing HAPE? Also, what about the duration of time that one spends in a state of increased cardiac output at altitude? Is HAPE more likely to develop?

    1. Liza

      From Tod Schimelpfenig: Yes, if you have pulmonary hypertension, hard exercise can worsen the problem, but hard exercise, but itself, does not cause HAPE. “Also, what about the duration of time that one spends in a state of increased cardiac output at altitude? Is HAPE more likely to develop?” I don’t know about this. I would say ‘maybe’ but first you need to have the underlying state of pulmonary hypertension from lack of acclimatization. Long stays at altitude do not by itself increase risk for HAPE which usually happens in the not-acclimitized in the first 24-48 hours.

  14. Adam Pratt

    My observation is that altitude affects different people very differently. For example, on one JMT Trip I was on the most fit person had the most severe altitude sickness. As ultrarunners we tend to think our fitness will help us overcome anything, but in my experience altitude is a real wildcard.

    1. Liza

      Mine too, Adam. I got to climb Mt. Kenya once on a work trip, and I was the fittest person and also the sickest person. Of course, sometimes fitter people just suffer more because they go up faster and higher.

  15. Eric

    I noticed there was no mention of using Acetazolamide (Diamox) to speed up acclimation. Cases like the scenario presented above would seem perfect for it’s use. I’ve used it with good results when I’ve needed to respond to SAR missions in the Sierra Nevada on short notice. Combine with some ibuprofen and you’ve got a 1-2 punch for AMS.

      1. Eric

        Thanks Bryon, I didn’t realize it was considered a banned substance by WADA! I guess anything that makes beers taste funny should be banned. (Common side effect is that carbonated beverages take on an odd taste.)

  16. Sarah Lavender Smith

    Hey Liza, I’ve been thinking a lot about this since I believe I suffered mild, not severe, altitude sickness at the Ouray 100 (due to headache & shortness of breath — but headache never got *too* bad). Lack of oxygen contributed to my stomach turning & my muscles weakening. I also had coughing and shortness of breath. However, after I suffered respiratory issues at San Juan Solistice 50 in June, and feared I was flirting with HAPE, I went to doc and he said no, it wasn’t HAPE (unlikely for me to develop because I’ve been living & acclimating at 9000 feet for two-plus months), it was delayed exercise-induced asthma aka bronchial spasms brought on by severely working my lungs, and potentially triggered by environmental factors such as pollen or smoke in air. Long story short, I feel altitude illness is a spectrum and I still don’t know how much to “suck it up” and suffer through it. I feel I could’ve/should’ve suffered thru it more at Ouray rather than DNFing after approx 27 hours. I also wanted to mention this because HAPE vs. asthma can be confusing. Thoughts? Thanks for great article.

    1. Liza

      Sarah, in your race report, you wrote: “I couldn’t catch my breath; even at this snail’s pace, I breathed heavily and rapidly as if recovering from a sprint. I tried a pattern of counting 20 steps, then pausing to lean on my trekking poles and breathe deeply for 10 breaths. But that didn’t help. I took a few hits off my new Albuterol inhaler…and it provided short-lived relief. My lungs were telling me—through coughing, burning and rapid breathing…”
      Whether these symptoms were due to HAPE or asthma, the standard practice in wilderness medicine is to get you out of that environment until the symptoms improve — especially with asthma if the symptoms didn’t improve with more aggressive use of the albuterol (4-8 puffs every 20 minutes up to 4 hours).
      Your question about knowing what to push through is the one we all want a definitive answer to. I do think you should use shortness of breath while you’re sitting or standing still plus coughing as a handrail. In that situation, a runner should ask themselves: “Am I willing to put my pacer in a bad or frightening situation? Because these symptoms mean that’s a definite possibility if I continue.” I make better decisions when I think about the impact on my pacers, crew and family.

      1. Sarah Lavender Smith

        Liza I just reread your asthma article from last year — so helpful. What you described is really what I’m dealing with. I have been in denial about having exercised-induced bronchoconstriction but the combo you describe of airway inflammation & gunk (mucus) and feeling like I’m breathing through a straw is it. I will use the puffer more aggressively. Thanks for all your wisdom in your past article and this one.

  17. Lam

    Eric, did you have further side effects? I’m doing TRR6 and getting a lot of mixed reviews.
    , so hesitant to take the med. I have the prescription packed.

    1. p

      I really don’t want to appear rude or offend but did you not read the bit about it being a banned substance? Please for the sake of our amazing sport do not consider taking any banned substances if you are participating in any kind of event, it is also not a great idea to be taking ibuprofen if participating in any kind of endurance activity.

  18. Brett Maune

    Sarah, regarding the EIA, it’s impossible to give a “correct” answer but from my experience with qualitatively similar conditions that develop over a similar time frame, I would say that the asthma would have continued to worsen to the point that you would be crippled on the ascents. Depending how much climbing remained, it may not have been possible to finish. Even if you could have finished, if the asthma had progressed to the point that you can only ascend at a slow rate then that means you can only uptake oxygen at a rate not significantly exceeding that which is required for basal metabolism. Basically, the margin between life and death is not that large. Not trying to be an alarmist here. These are just my thoughts on the condition, which is extremely frustrating. Lastly, in my experience there is no discernable benefit from asthma medication.

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