Going to Denver? Start here, not on arrival.
How to Avoid Altitude Sickness in Denver
Most altitude sickness in Denver is preventable, and almost all of the prevention happens in decisions you make before you're symptomatic — what you do on the plane, what you do the first evening, and whether you go higher on day one.
None of it is complicated and none of it costs anything. What follows is the practical version, roughly in order of how much difference each step makes.
Before you fly
1. If you've been badly altitude sick before, talk to your doctor. A previous bad episode is the strongest single predictor of another one. Prescription options for prevention exist — acetazolamide is the common one — and it's typically started the day before ascent. It isn't right for everyone: sulfa allergies, kidney disease, pregnancy and several drug interactions all matter. This is a conversation with your own clinician before you travel, not something to sort out on arrival.
2. Build in a slower ascent if the mountains are on the itinerary. Flying into Denver and driving straight to a resort at 9,000+ feet the same day is the single riskiest common itinerary in Colorado. Two nights in Denver first is genuinely protective. Details: Altitude Sickness in Colorado
3. Arrive rested. Poor sleep and a red-eye make everything about the first 24 hours harder.
Your first 24 hours in Denver
4. Take it easy — genuinely easy. This is the highest-value thing on the list. No hikes, no gym, no ambitious walking tour, no Red Rocks stairs on day one. Your body is already working harder than usual at rest.
5. Skip alcohol. Alcohol at 5,280 feet hits harder, worsens dehydration, and disrupts the breathing pattern during sleep at exactly the point your body is adjusting. The first night is the one that matters most.
6. Drink steadily — but don't force it. Dry Colorado air and faster breathing mean you lose more fluid than you notice. Aim for pale-yellow urine. Chugging large volumes doesn't prevent altitude sickness and can cause genuine problems of its own.
7. Eat carbohydrates. Your body metabolises them more efficiently than fat at altitude. Not a dramatic effect, but it's free.
Your first 48 hours
8. Sleep matters more than you'd think. Broken sleep is common the first night. Avoid sleeping pills and sedatives entirely — they suppress breathing when you least want that. If you're propped up slightly, some people find it easier.
9. Don't ascend until you feel normal. If you've got a headache in Denver, going up to Breckenridge that afternoon is how a mild problem becomes a real one. The rule that matters at every elevation: don't go higher with symptoms.
What doesn't prevent altitude sickness
There's a small industry in Denver built on the first day of your trip. Most of it doesn't do what it implies.
- Oxygen bars. Recreational, not medical. A few minutes of scented oxygen may feel pleasant; it does not acclimatize you, and any effect ends when the cannula comes off.
- IV hydration. Treats dehydration, which is a real contributor to feeling bad — but it does not address the oxygen deficit that causes altitude sickness, and there is no evidence it prevents it. Getting an IV on arrival "just in case" isn't a prevention strategy.
- Altitude supplements and chewables. Widely marketed, poorly evidenced.
- A one-off session in a simulated-altitude room. Meaningful altitude training takes sustained, repeated exposure over weeks. One session before a trip doesn't replicate it.
- Coca or herbal preparations. Traditional in some high-altitude regions; not a substitute for a sensible ascent.
- Extreme hydration. Covered above — more is not better past a point.
None of these are dangerous in themselves. They just aren't prevention, and buying one shouldn't change how carefully you follow the steps above.
What actually works is unglamorous: ascend slowly, rest on arrival, skip alcohol, stay reasonably hydrated, don't go higher with symptoms, and — if you have a history — talk to your doctor beforehand.
If you're moving to Denver rather than visiting
The adjustment is the same for the first few days, but full acclimatization takes one to three weeks and, for some people, longer before exercise feels normal again. Expect your running pace to be off for several weeks. Expect to need more water than you did at sea level, permanently. Sleep usually settles within the first week or two.
Timeline in detail: How Long to Acclimate to Denver's Altitude
Prevention stops here
If symptoms are already present, prevention advice no longer applies — the rules change to: don't ascend, rest, and descend if you're not improving.
Get emergency care for: breathlessness at rest · confusion or trouble walking straight · a cough with frothy or pink sputum · blue or grey lips · oxygen saturation below 88–90%.
Symptom detail and what to do: Denver Altitude Sickness Symptoms
Frequently asked questions
How long before my trip should I start preparing?
For most people, no advance preparation is needed beyond planning a sensible itinerary. If you have a history of altitude sickness, speak to your doctor at least a week or two before travelling so there's time to discuss prescription prevention.
Does being fit protect you from altitude sickness?
No. Fitness has little bearing on who gets altitude sickness, and fit travellers sometimes fare worse because they exert themselves earlier and harder on arrival.
Should I drink extra water on the flight?
Drinking normally on the flight and after landing is sensible — cabin air is dry and dehydration worsens symptoms. Extra beyond normal thirst isn't necessary or helpful.
Can I drink alcohol at all in Denver?
After the first 24–48 hours, most people are fine with normal moderation. It's the first night, when your body is adjusting, that's worth protecting.
Is it safe to exercise in Denver?
Yes, after you've adjusted. Give it a day or two, then build back gradually — expect to be slower and more breathless than usual for a couple of weeks. ---