Prophylaxis and treatment of AMS

Hello there,
I’m emailing with questions about altitude medicine for the Himalaya trek. I live in Denver, Colorado and we are trekking to EBC at the end of this month. I think the most we will ascend is about 2000 ft at a time with a rest day the next day.
It is with the Wilderness Medicine group.

Of course I am concerned about atlitude illness, so I have prescriptions for acetazolamide, decadron, and am considering an emergency Lasix prescription.

I understand that altitude illness is difficult to predict, but I am wondering since we have hiked the Inca Trail to Machu Picchu (not as high as EBC by any means) but we had no problems on that trek, what your opinion is on the likelihood of altitude illness.

Do you have to take Acetazolamide/Decadron prophylactically or can you wait and take it if you get sick. I am worried about prophylaxing in the case that I do get sick there won’t be much to do for myself other than descend.
Thank you for your help

Thanks for your question to

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The difference between the Inca Trail trek and the EBC trek, as you rightly point out, is the maximum altitude you attain on the Inca trail is 4215m and this is a pass – the highest trekkers sleep is usually 3800m. So, EBC is a different proposition as you will be trekking up to 5300m. The fact that you did not experience any altitude problems on the Inca Trail is a hopeful sign, but every time you go to altitude your body can react differently, especially if you have been unwell in any way (for example if you get any infection). One thing you could do in the week before you go to Nepal is to get up into the mountains in Colorado, not only to keep hiking fit but to expose yourself to some relative altitude before you go.

I’m sure that, if you are trekking with the Wilderness Medicine group, they will be ascending according to their guidelines – ie only increasing sleeping altitude by 300-500m/day with a rest day every 3 days or 1000m. All my advice is based on these guidelines (as well as the UIAA ones) which are available to download from the Web.

Regarding prophylaxis; As recommended by the WMS guidelines, slow ascent is the best way to prevent Acute Mountain Sickness (AMS) which is the most common form of altitude illness. Acetazolamide is the best drug for both prophylaxis and treatment of AMS so it is good to carry some with you. Another important way of helping prevent illness is to stay well hydrated (so that you are peeing clear urine regularly) to keep yourself warm, take plenty of rest and to eat regularly.

One recommendation I would make is to take a dose of Acetazolamide at home before you leave on your trip, to make sure firstly you don’t have any reaction to it (this is unusual ) and also so you have felt some of the side effects it may give you before you are already at altitude. The most common side effects are having to urinate more (which is actually one of the way it works) and tingling in your hands and feet. Some people feel this and some don’t. When I take Diamox I usually get quite electric tingling which comes and goes in my feet but usually only lasts for a short time. The prophylactic dose is 125mg (usually ½ a tablet as tablets usually contain 250mg – please check this on your tablet information).

In terms of if or when you should take Acetazolamide (also known as Diamox), I would not take it unless you start feeling the early signs of AMS, for example getting a headache in the evening after ascent which is gone by the morning or if you are not sleeping well (in this case you can take a dose of 125mg about 2 hours before bed just as a sleeping aid). You can then start a prophylactic dose – 125mg twice a day – and if this helps the symptoms carry on taking this until you are descending again. Taking this will not mask any worsening symptoms so you will know if you are getting sick, in which case you should be upping the dose to 250mg (one tablet) twice a day and certainly not going any higher, probably descending. All these decisions should be taken in conjunction with the Medic on your trip.

It is not recommended to use Decadron/Dexamethasone as prophylaxis for AMS unless you do find that you have a reaction to Acetazolamide. It should be in the first aid kit for your group but I would not recommend that you need to carry it in your own personal kit.

Lasix is not recommended and has no place in prophylaxis or treatment of AMS or any other altitude illness. It is a diuretic like Acetazolamide but it works in a different way and can cause significant dehydration which can actually worsen symptoms as people tend to be dehydrated already when unwell at altitude.

I hope this helps.

Dr Kitty Duncan

| June 1st, 2013 | Posted in Questions to the mountain doc team |

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