I did Kilimanjaro a few years ago with a college alumni group. None of us knew each other until we met at the airports. . It’s a great experience.
A few thoughts:
Everyone took Diamox. It helps you acclimate to altitude faster than your body normally would. It also makes you pee like crazy.
The 5 day trips up the mountain have a success rate less than 25%. The success rate of the longer 8,9, and 10 day trips is upwards of 90+%. Go for the longest trip.
As someone noted earlier, be sure to go with a dependable outfitter. Yes, you’ll pay more, but you’ll be glad you did for many reasons. The most important reason is they will make sure you walk at an increasingly slower pace as you get higher on the mountain. Otherwise, the more quickly you walk, the more likely you’ll not make it.
Whatever the length of the trip is, they all take 1.5 days to get down. So if you see a 9 day trip, you can assume you’ll be climbing for 7.5 days.
I did it in my late 50s. For prep, I joined a gym and exercised for an hour each day, including swimming, running, and cycling. I suggest you do something similar.
Our trailhead was a 7000 ft, and we hiked to 9000 feet the first day, and did 2K-3+K/day. We also hiked down 2K one day to sleep and to better acclimate.
Bring extra cash to tip the porters. They work very hard for you. There will be one who will carry your bag of gear. Your bag cannot weight more than 32 or 33 lbs. The park officials weigh all porters bags at the trailheads. They do this to prevent abuse of the porters.
The group you’re hiking with will play a big role in how much you enjoy the hike. Ours was great.
My H and Kids have had altitude sickness on several different vacations. It’s miserable and you just have to get down them the altitude as soon as you can. It can be unpredictable, as you can be perfectly fine at altitude on most trips and then out if the blue you can get a bad case if altitude sickness on another.
Not drinking alcohol is important to minimize chance of altitude sickness. Also gradually increasing your altitude is useful and helpful–start at lower elevation and gradually work your way higher.
Your physician may have additional suggestions and tips. I’ve also hear Diomox can help.
My neighbor did it. He really trained, and had lived at altitude in the Peace Corps in Nepal previously.
Regarding Kathmandu, it is the same, or lower altitude than Denver. No big deal for most folks, though some feel it. . For trekking in Nepal, or elsewhere, take your time. I did the Annapurna trek, which crosses a 17,00 foot pass, by walking up very slowly, and staying at 14,000 feet for a few days. I do remember feeling very lightheaded at the top, and people seemed like zombies around me as each step was a lot of work.
A friend who teaches back country leadership skills, states she cannot do altitude over 8000’ or so. She gets sick every time, fit or not. My impression is that diamox is for problems that arise, not a preventative measure. Perhaps the recommendations have changed?
My sister lives in Denver so 5280 ft, also has a home in Silverthorne (9000 ft), has climbed 14ers, skies at Copper [top elevation 12,300 ft] and still gets altitude sickness occasionally. Just happens.
Being fit can help avoid altitude sickness somewhat but one’s reaction to altitude can really vary from person to person. Additionally, traveling in some of these places, if you get a stomach bug or some reaction to the local diet, any type of even mild dehydration, or other physical ailment, even minor, at a high altitude, it can knock you off your feet.
Diamox can be used both to prevent and relieve altitude sickness as it accelerates acclimation rates. It’s also a diuretic so an effort needs to be made to stay hydrated. There are also other side effects. Oh, and carbonated beverages - soda, beer - will taste like swill while you are on it.
My kids and H were fit when they were afflicted by altitude sickness. The main thing is to listen to your body and be willing and able to promptly get to lower altitude if your body is telling you or a companion the altitude isn’t working for you.
I agree that any little “bug” that could be a mild problem at lower altitude can increase the likelihood of altitude sickness as well and require retreat to lower altitude. One trip both D and H were afflicted and spent several days lying down and recovering once we got down from altitude to sea level.