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So it's important to follow the Golden Rules and not push on if you experience symptoms. Rapid descent will always resolve early symptoms - the problem is that denial is extremely common as people are keen to reach their goal and not disrupt the rest of the party. This is how the serious issues occur.

In the UK, the clinical authorities recommend against using Diamox prophylactically, so you won't get a prescription. It's available in the US, but the risk/reward ratio doesn't look good and you certainly shouldn't rely on it preventing AMS at 14k.

So it's important to follow the Golden Rules and not push on if you experience symptoms. Rapid descent will always resolve early symptoms - the problem is that denial is extremely common as people are keen to reach their goal and not disrupt the rest of the party. This is how the serious issues occur.

In the UK, the clinical authorities recommend against using Diamox prophylactically, so you won't get a prescription. It's available in the US, but the risk/reward ratio doesn't look good and you certainly shouldn't rely on it preventing AMS at 14k.

Edit: I've adjusted the broken Golden Rules link with some that I searched up. I'm not the OP, who knows way more, but they look fairly in line with what previous casual research showed me.

Some of the answers here are, frankly, dangerous.

According to the Altitude Research Centre:

Being physically fit does not prevent you from experiencing AMS symptoms. There does not seem to be a link between fitness level and susceptibility to altitude illness.

I've climbed with highly conditioned endurance athletes, and can tell you from experience that they have much the same risk of altitude sickness as everybody else.

Altitude medics classify 14,000 feet as "Very High Altitude" which is a strong hint that you should treat it with respect.

At 14,000' (4,200m) you're only getting 60% of the oxygen you're used to at sea level. Around 80% of people are prone to altitude sickness of varying degrees if they ascend quickly to this altitude. Are you feeling lucky?

Without acclimatisation, most people will experience mild altitude sickness from around 8,000' (2,400m) with a significant risk of disabling sickness from around 12,000' (3,600m).

Don't underestimate the dangers. Even mild sickness is extremely unpleasant and can affect your ability to move safely on technical ground. Severe symptoms can be pretty much paralysing.

Bottom line: it would be extremely rash to go straight up to 14,000' (4200m) without acclimatising properly - you could end up in severe difficulties.

It is essential to acclimatise properly before ascending to 14,000 feet (4,200m)

If you want to climb fourteen-thousanders, you only have two proven alternatives - either you allocate 3-4 days to training at lower altitude, or you pre-acclimatise with altitude tents and masks.

I only have direct experience of traditional training. I'm prone to sickness, so personally I find it best to be conservative and climb up to around 9,000' (2,700m) on the first day while sleeping low. Even this can be quite uncomfortable. Then I'll add 1,000' (300m) or so a day if things go OK. If I'm relatively symptom-free on an 12,000' training climb, I'd feel ready for 14,000' (4,200m).

This regime is for typical alpine work where you are sleeping low. If you are on a traverse or trek where you will be sleeping high for multiple nights you have to go slower and bail out at the first sign of serious symptoms. Here is a sobering account of a fit young woman who died of edema after ascending to 14,500' on the 5th day of a trek in Nepal.

The only alternative is to pre-acclimatise using altitude tents and masks. This is quite an expensive and disruptive process, but may be worth it if you simply can't find the time to acclimatise on the hill. The equipment can be hired or purchased if you don't have a suitable facility nearby. US Army Research suggests that tents are better than nothing, but are far from a full substitute for traditional acclimatisation.

Medications should only be used in specific circumstances. Dioxin has significant (and potentially life-threatening) side-effects and is discouraged for routine recreational use by the UK National Health Service. Plus recent research on Kilimanjaro suggests that it is not very effective when used for rapid and strenuous ascents.

[Edited after comments and additional research.]

Some of the answers here are misleading. According to the Altitude Research Centre:

Being physically fit does not prevent you from experiencing AMS (Acute Mountain Sickness) symptoms. There does not seem to be a link between fitness level and susceptibility to altitude illness.

At 14,000' (4,200m) you're only getting 60% of the oxygen at sea level. Altitude medics classify 14k as "Very High Altitude" which is a strong hint that the dangers are significant.

Susceptibility to AMS appears to be genetic and varies widely between individuals. Estimates of incidence levels are all over the place in the literature, but we can safely say that a significant percentage will experience quite severe physical and cognitive issues if they ascend rapidly to 14k.

Don't underestimate the impact. Even mild AMS is extremely unpleasant and can affect your ability to move safely on technical ground. Severe symptoms can be pretty much paralysing. I'm very susceptible to AMS and know this from experience.

So it's important to follow the Golden Rules and not push on if you experience symptoms. Rapid descent will always resolve early symptoms - the problem is that denial is extremely common as people are keen to reach their goal and not disrupt the rest of the party. This is how the serious issues occur.

Currently, the only way to know your own response to altitude is to suck it and see. So it's important to be cautious on your first high ventures, and pick routes with an easy retreat. Even people with known low susceptibility can suddenly experience problems, so always be prepared to descend if you feel unwell.

How to acclimatise before ascending to 14,000 feet (4,200m)

It's very important to distinguish between two scenarios:

1. The typical alpine trip where you make day-climbs to the peak, but descend to sleep below 8000 feet (2400 meters). That is what we are discussing here.
2. A trip where you will be progressively sleeping at higher altitudes. This is a whole different ballgame and life-threatening problems are quite common. Do your research and understand the proper protocols for gaining height.

Traditional acclimatisation

The only proven way to acclimatise fully is a programme of training climbs at increasing altitudes. If you know you are one of the lucky ones, you can head straight off to your 14 thousander. For the rest of us, you'll need 1-4 days to acclimatise depending on your physiology.

I'm prone to sickness, so personally I find it best to be conservative and climb up to around 9,000' (2,700m) on the first day while sleeping low. Even this can be quite uncomfortable. Then I'll add 1,000' (300m) or so a day if things go OK. If I'm relatively symptom-free on an 12,000' training climb, I'd feel ready for 14,000' (4,200m). If you're less susceptible, you can accelerate the process. Only experience will tell.

Altitude tents and masks

This is quite an expensive and disruptive process. The equipment can be hired or purchased if you don't have a suitable facility nearby. US Army Research suggests that tents are better than nothing, but are far from a full substitute for traditional acclimatisation. For a 14 thousander, it's unlikely that this will be the way to go.

Medication

The only recognised medication is Diamox (Acetazolamide).

Diamox is far from risk-free, with many unpleasant but benign side-effects and occasional life-threatening reactions. And recent research suggests that it is not measurably effective for countering the effects of strenuous exercise during rapid ascent.

In the UK, the clinical authorities recommend against using Diamox prophylactically, so you won't get a prescription. It's available in the US, but the risk/reward ratio doesn't look good and you certainly shouldn't rely on it preventing AMS at 14k.

Take-home points

• The dangers of rapid ascent to 14k are significant
• Only experience will tell you how long you take to acclimatise
• If you do need acclimatisation, the only proven approach is traditional training climbs
• Tents and masks only provide modest benefits, while medication has significant side-effects and may well not work in this scenario.

Some of the answers here are, frankly, dangerous.

Aerobic training will not prepare you for altitude

According to the Altitude Research Centre:

Being physically fit does not prevent you from experiencing AMS symptoms. There does not seem to be a link between fitness level and susceptibility to altitude illness.

I've climbed with highly conditioned endurance athletes, and can tell you from experience that they have much the same risk of altitude sickness as everybody else.

Altitude sickness is a significant risk at 14,000 feet (4,200m)

Altitude medics classify 14,000 feet as "Very High Altitude" which is a strong hint that you should treat it with respect.

At 14,000' (4,200m) you're only getting 60% of the oxygen you're used to at sea level. Around 80% of people are prone to altitude sickness of varying degrees if they ascend quickly to this altitude. Are you feeling lucky?

Without acclimatisation, most people will experience mild altitude sickness from around 8,000' (2,400m) with a significant risk of disabling sickness from around 12,000' (3,600m).

Don't underestimate the dangers. Even mild sickness is extremely unpleasant and can affect your ability to move safely on technical ground. Severe symptoms can be pretty much paralysing.

Bottom line: it would be extremely rash to go straight up to 14,000' (4200m) without acclimatising properly - you could end up in severe difficulties.

It is essential to acclimatise properly before ascending to 14,000 feet (4,200m)

If you want to climb fourteen-thousanders, you only have two proven alternatives - either you allocate 3-4 days to training at lower altitude, or you pre-acclimatise with altitude tents and masks.

I only have direct experience of traditional training. I'm prone to sickness, so personally I find it best to be conservative and climb up to around 9,000' (2,700m) on the first day while sleeping low. Even this can be quite uncomfortable. Then I'll add 1,000' (300m) or so a day if things go OK. If I'm relatively symptom-free on an 12,000' training climb, I'd feel ready for 14,000' (4,200m).

This regime is for typical alpine work where you are sleeping low. If you are on a traverse or trek where you will be sleeping high for multiple nights you have to go slower and bail out at the first sign of serious symptoms. Here is a sobering account of a fit young woman who died of edema after ascending to 14,500' on the 5th day of a trek in Nepal.

The only proven alternative is to pre-acclimatise using altitude tents and masks. This is quite an expensive and disruptive process, but may be worth it if you simply can't find the time to acclimatise on the hill. The equipment can be hired or purchased if you don't have a suitable facility nearby. US Army Research suggests that tents are better than nothing, but are not a full substitute for traditional acclimatisation.

Medications should only be used in specific circumstances. They have significant side-effects and are discouraged for routine recreational use. Plus the evidence suggests that they are not measurably effective when used for rapid and strenuous ascents.

Some of the answers here are, frankly, dangerous.

Aerobic training will not prepare you for altitude

According to the Altitude Research Centre:

Being physically fit does not prevent you from experiencing AMS symptoms. There does not seem to be a link between fitness level and susceptibility to altitude illness.

I've climbed with highly conditioned endurance athletes, and can tell you from experience that they have much the same risk of altitude sickness as everybody else.

Altitude sickness is a significant risk at 14,000 feet (4,200m)

Altitude medics classify 14,000 feet as "Very High Altitude" which is a strong hint that you should treat it with respect.

At 14,000' (4,200m) you're only getting 60% of the oxygen you're used to at sea level. Around 80% of people are prone to altitude sickness of varying degrees if they ascend quickly to this altitude. Are you feeling lucky?

Without acclimatisation, most people will experience mild altitude sickness from around 8,000' (2,400m) with a significant risk of disabling sickness from around 12,000' (3,600m).

Don't underestimate the dangers. Even mild sickness is extremely unpleasant and can affect your ability to move safely on technical ground. Severe symptoms can be pretty much paralysing.

Bottom line: it would be extremely rash to go straight up to 14,000' (4200m) without acclimatising properly - you could end up in severe difficulties.

It is essential to acclimatise properly before ascending to 14,000 feet (4,200m)

If you want to climb fourteen-thousanders, you only have two proven alternatives - either you allocate 3-4 days to training at lower altitude, or you pre-acclimatise with altitude tents and masks.

I only have direct experience of traditional training. I'm prone to sickness, so personally I find it best to be conservative and climb up to around 9,000' (2,700m) on the first day while sleeping low. Even this can be quite uncomfortable. Then I'll add 1,000' (300m) or so a day if things go OK. If I'm relatively symptom-free on an 12,000' training climb, I'd feel ready for 14,000' (4,200m).

This regime is for typical alpine work where you are sleeping low. If you are on a traverse or trek where you will be sleeping high for multiple nights you have to go slower and bail out at the first sign of serious symptoms. Here is a sobering account of a fit young woman who died of edema after ascending to 14,500' on the 5th day of a trek in Nepal.

The only alternative is to pre-acclimatise using altitude tents and masks. This is quite an expensive and disruptive process, but may be worth it if you simply can't find the time to acclimatise on the hill. The equipment can be hired or purchased if you don't have a suitable facility nearby. US Army Research suggests that tents are better than nothing, but are far from a full substitute for traditional acclimatisation.

Medications should only be used in specific circumstances. Dioxin has significant (and potentially life-threatening) side-effects and is discouraged for routine recreational use by the UK National Health Service. Plus recent research on Kilimanjaro suggests that it is not very effective when used for rapid and strenuous ascents.