Medic Minute # 3 – Illness at altitude

Colorado has a way of humbling people fast. Somebody comes in from lower elevation, feels great, wants to hike hard, maybe have a couple drinks, maybe skip water, maybe prove their cardio is amazing, and then by that evening they feel like hammered dog shit. Headache. Nausea. No appetite. Trouble sleeping. No energy. Sometimes it stops there. Sometimes it doesn’t.

That is part of what makes altitude illness tricky. It often starts looking like something people want to dismiss. They blame dehydration, bad sleep, travel, maybe a hangover, maybe the fact that they pushed too hard on day one. Sometimes they are partly right. But sometimes what they are looking at is the early stage of a problem that can get dangerous if they keep climbing, keep pushing, or keep pretending they are fine.

If you spend time in the mountains, or if you bring students, family, clients, or friends into the mountains, you need to understand altitude illness. This is especially true in Colorado, where plenty of people go from near sea level to 8,000 or 10,000 feet in a matter of hours and act like the body should just accept that without complaint. Sometimes it does. Sometimes it doesn’t.

This article is not about scaring people away from the mountains. It is about helping people recognize the problem early, make better decisions, and understand when altitude illness is just uncomfortable and when it is becoming an emergency.

Why Altitude Hits People So Hard

The main issue at altitude is not that the air suddenly has no oxygen in it. The percentage of oxygen in the air stays about the same. The problem is that as elevation increases, air pressure drops. That means each breath delivers less usable oxygen pressure than your body is used to at lower elevation.

Your body can adapt, but it needs time.

That adjustment process is called acclimatization. Over the first few days at altitude, your body increases breathing, makes other short-term physiological adjustments, and slowly gets better at functioning in a lower-oxygen environment. If you go too high too fast, or if your body simply doesn’t adapt well, altitude illness can develop before acclimatization catches up.

This is where people get themselves in trouble. They think being fit makes them immune. It does not. The mountain does not care how much you deadlift. It does not care how fast you run a 10K. Good fitness may help you perform better in the mountains, but it does not protect you from altitude illness.

Some people acclimatize well. Some do not. Some have mild symptoms one trip and bigger problems the next. The best predictor is how you have responded before, but even that is not a guarantee.

The Three Main Altitude Problems

Altitude illness generally gets discussed in three categories:

• AMS: Acute Mountain Sickness
• HAPE: High-Altitude Pulmonary Edema
• HACE: High-Altitude Cerebral Edema

AMS is the common one. HAPE and HACE are the dangerous ones.

Think of AMS as the warning shot. HAPE and HACE are the situations where people can deteriorate quickly and get into very real trouble.

Acute Mountain Sickness: The Common Problem

Acute Mountain Sickness is the form most people are talking about when they say they got “altitude sickness.” It commonly shows up in the first several hours to first day after gaining elevation, often after the first night.

The classic symptom is headache after a recent ascent. That headache is often joined by one or more of the following: nausea, poor appetite, dizziness, fatigue, or vomiting. People often describe feeling wrung out, sluggish, irritable, and just generally off. It can feel a lot like a hangover, which is especially convenient if the person has also been drinking and wants a built-in excuse.

A mild case of AMS is miserable, but not necessarily catastrophic. The danger comes when people ignore it and keep gaining altitude or pushing hard. Mild AMS can remain mild, improve with rest and acclimatization, or progress.

A few practical points matter here. If symptoms begin several days after arrival without a further ascent, altitude illness becomes less likely and something else should be considered. Also, not every headache at altitude is AMS. Dehydration, exertion, poor sleep, migraine, illness, and carbon monoxide exposure can all muddy the picture. But if someone recently ascended and has headache plus the other typical symptoms, altitude illness belongs high on the list.

High-Altitude Pulmonary Edema: Trouble in the Lungs

HAPE is one of the serious altitude emergencies. This is not just somebody being short of breath because they hiked uphill. This is a problem involving fluid accumulation in the lungs, and it can become life-threatening.

Early on, HAPE may look like unusual breathlessness with exertion, decreased performance, chest congestion, or a cough. The person may look like they are working way too hard for the level of effort. As it worsens, breathing becomes harder even at rest. The cough may worsen. The person may look weak, pale, exhausted, and increasingly distressed.

What makes HAPE dangerous is that people sometimes explain it away. They think they are out of shape, getting a cold, or just struggling because of the altitude in the ordinary sense. Meanwhile, the problem is getting worse.

If someone at altitude is getting more short of breath instead of settling in, if their exercise tolerance suddenly drops off, or if they are having trouble breathing at rest, that is not a “walk it off” situation.

High-Altitude Cerebral Edema: Trouble in the Brain

HACE is another severe altitude emergency, and it can kill people. It often develops from worsening altitude illness, and it can accompany HAPE.

Where HAPE is mainly a lung problem, HACE is a brain problem. The red flags include ataxia, which means loss of coordination or a staggering gait, along with confusion, altered mental status, drowsiness, or strange behavior. The person may look intoxicated when they have not been drinking, or they may become increasingly difficult to assess because their thinking is clearly not right.

This is the kind of thing that should stop everyone in their tracks.

If someone is at altitude and cannot walk normally, is acting confused, or seems neurologically off, treat it as an emergency until proven otherwise. Do not sit there debating it like a committee. Do not let them go lie down in a tent by themselves. Do not let them tell you they are fine when they are weaving around like they just left a bar at closing time.

What People Get Wrong

One of the biggest mistakes people make is treating altitude symptoms like a personal insult. They do not want to slow down. They do not want to be the person who is holding up the group. They do not want to admit the plan needs to change. So they negotiate with reality.

That usually goes poorly.

Another mistake is arriving at altitude and immediately going hard. Travel day is not the time to set personal records. If you have just come up from lower elevation, the smart move is usually to take it easier, hydrate, eat, and let your body start adjusting.

People also tend to assume hydration is the whole answer. Hydration matters, but it is not magical. You cannot outdrink poor acclimatization. You can be well hydrated and still get sick at altitude.

And, as mentioned earlier, fitness is not immunity. Strong hikers, runners, athletes, and hard-charging type-A people get altitude illness too. Sometimes those are the exact people who make things worse because they are mentally wired to push through discomfort.

Prevention: The Smart Way to Stack the Odds

The best prevention is simple in theory and inconvenient in practice: gain altitude gradually.

If possible, spend a couple nights at a moderate elevation before sleeping much higher. Once you are above roughly 8,000 to 10,000 feet, gaining sleeping elevation too rapidly increases the risk. The higher you go, the more important pacing becomes.

There are also some common-sense field habits that help. Take it easy for the first day or two. Do not overexert early. Stay reasonably hydrated. Avoid excessive alcohol, especially when you first arrive. Eat even if your appetite is not great. Pay attention to how everyone in your group is doing, especially the people who insist they are “good” while clearly not being good.

For some people, especially those with prior altitude problems or unavoidable rapid ascent, a medical provider may recommend preventive medication such as acetazolamide. That is a discussion worth having ahead of time, not after you are already sick and parked on a mountainside wishing you had planned better.

What To Do If Symptoms Start

If someone develops mild AMS, the first big rule is this: do not keep going higher while symptoms are active.

That alone prevents a lot of bad decisions.

For mild symptoms, staying at the same altitude, resting, limiting exertion, hydrating, and treating the headache or nausea may be enough while the body acclimatizes. Some people improve over the next 12 to 48 hours if they stop ascending and stop acting like they are invincible.

If symptoms worsen, if the person cannot function, or if you see signs suggesting HAPE or HACE, the response changes. Descent becomes a priority.

For AMS, a descent of around 1,000 feet or more can make a significant difference. For HAPE or HACE, descent is not just helpful. It is urgent. Oxygen, when available, is useful. In more advanced wilderness medicine systems, medications and portable hyperbaric chambers may also be part of care, but the average person reading this should remember the main thing: serious altitude illness is not solved by hanging out and hoping.

Go down. Get help.

If the person has confusion, ataxia, severe weakness, difficulty breathing at rest, or otherwise looks seriously ill, this is a medical emergency.

Why This Matters at The Survival University

Our mountain training environment is not Himalayan expedition altitude, but it is high enough to matter. People come from lower elevations to train, camp, hike, and work in the Colorado mountains, and some of them feel the difference fast.

That is one reason wilderness medical training matters so much. It is not just about learning big dramatic rescue skills. It is about recognizing problems early, understanding what they mean, and making decisions that prevent a manageable situation from turning into a full-blown emergency.

Altitude illness is one of those subjects where a little knowledge can go a long way, provided you apply it in time.

The Bottom Line

Altitude illness is real, common enough to deserve respect, and sometimes deadly. Most of the time it begins with symptoms that are easy to dismiss, especially if someone is stubborn, tired, embarrassed, or determined to keep the plan on track.

Do not let that be you.

If you have a headache after ascending and feel nauseated, wiped out, dizzy, or generally miserable, pay attention. If breathing problems, coordination problems, or mental-status changes enter the picture, stop playing games and treat it like the emergency it may be.

The mountains are not out to get you, but they do not care whether you understand physiology. The more you know, the earlier you recognize the problem, and the faster you make the right call, the better your chances of keeping a rough day from becoming a disaster.

If you want to build the kind of judgment and hands-on skills that help in real wilderness problems, take a look at our Wilderness First Aid, Wilderness First Responder, and other upcoming courses.