I’m not a doctor so I cannot offer advice here. All I can do is tell you what I do but it’s up to you what you do.
Make sure you are up-to-date on routine vaccines. These vaccines include measles-mumps-rubella (MMR) vaccine, diphtheria-pertussis-tetanus vaccine, varicella (chickenpox) vaccine, and your yearly flu shot. Get hepatitis A and B, Typhoid and anything else your doctors recommends. You can have a rabies jab but I don’t bother. Rabies is endemic in Nepal but most vicious dogs are to be found in cities, mountain dogs tend to be peaceable creatures.
I never bother with malaria drugs because outside of the wet season there is no malaria. This is quoted from CIWEC Clinic Travel Medicine Center in Kathmandu: ‘Although there are reports of about 5000 malaria cases with 10 deaths per year among the Nepalese, the risk for the average tourist or expatriate seems very low in Nepal. In the 26 year history of the CIWEC Clinic taking care of travelers and expatriates, there have only been 2 cases of Vivax malaria that may have been acquired from within Nepal. We believe that there is no malaria risk in Kathmandu, Pokhara or the mountain trekking areas. This being said, malaria does exist in the southern belt of Nepal (the Terai) and risk is highest in the hot, rainy summer monsoon.’
The other thing which you may get is the infamous ‘Delhi Belly’ which can be mainly avoided by eating clean hot food. Never eat anything that’s cold. That and personal hygiene. Carry some hand alcohol rub if you like. Clean water is a must – see below. Some people develop ‘Khumbu cough’ a dry hacking cough so you may want to take cough medicine. Carry antibiotics for chest, gut and general infections. You may be some distance from a doctor so it pays to be prepared. All these drugs are available in Nepal and are cheaper than in the UK. The best places to buy medical drugs that aren’t counterfeit are found opposite the Kathmandu Teaching Hospital in the north of the city. Taxis from Thamel cost about 350Rs, about £3.
Diamox, available from your doctor or cheaply in Kathmandu, aids acclimatisation and greatly benefits some people. You’ll see whole groups taking it and some guides dish it out like sweets. I’m of the opinion that if you need continuous Diamox you shouldn’t be there – go down until you feel better. A natural, slow acclimatisation is best though a moderate 2 to 3 days on Diamox to, say, get you over a pass is ok.
The three things you must know about are drinking water quality, hydration and high altitude sickness (AMS). The first is awful and can ruin your holiday and the second can lead to the third which potentially can kill you.
Don’t trust the water! Even apparently safe sources are not safe and, by that, I mean bottled water isn’t safe. This is apart from the environmental cost of all those plastic bottles that end up being burnt or thrown in the river. I always use a Katadyn water filter which means I can have fresh water anywhere. To make doubly sure use a good filter and add Lugol’s iodine but, as with other chemicals, adjust the purification time as the water is cold. Regular water purification pills are ok but you’d have to carry a lot for the trip. Boiled water is good but not always available and not always cool enough to drink. It also costs money, a litre can cost over a pound. If you want a one shot cheap answer, then iodine is it, but it tastes pretty bad. I strongly suggest that you read this article and the related information about water treatment.
The air at altitude is dry and you will lose a lot of body fluid. Remaining hydrated is the most important thing, so aim to drink 2-3 litres per day in the form of water, tea, soup, etc. If your pee is dark you need more water. It’s possible to drink too much water so 3 litres maximum but, if in doubt, ask a doctor. If you get dehydrated you WILL get altitude sickness. Acute mountain sickness (AMS) and especially HACE can kill you. I strongly suggest that you read this article and the related information about AMS.
Go slowly, don’t race up hills and listen to your body. The rule of thumb is not more than 500mts altitude gain a day, but some days that’s unrealistic and you’ll end up doing more. A headache may be a warning that you’re gaining height too quickly or more likely that you are dehydrated. A real persistant headache especially when it feels like a ever tightening steel band around your head is a sign of cerebral oedema (HACE) which will kill you. You must go down immediately. If in doubt about anything go down. Your Nepal Professional Mountain Guide will always keep an eye on you but he’s not medically trained and you are ultimately responsible for yourself. By the same token, Nepalis are not immune to getting ill. Very rarely they can get AMS and it’s incumbent upon you to watch them too. It must be said that other organisations sometimes use lowland guides and porters who aren’t used to the mountains. Porters, especially, can be poorly equipped for the cold. Of course Nepal Professional Mountain Guides use only the best people for the job.
All of this sounds pretty horrendous but there’s no need to worry. It’s all common sense and the water and food advice applies to many countries. Just remember that you are a long way from a hospital and need to be reasonably self sufficient. In an emergency your guide will call in a rescue helicopter.
Regarding helicopters: some unscrupulous trekking outfits will call in a helicopter at the earliest opportunity. It sounds caring but it’s really about the commission that they get from the helicopter people as rescues are often £5000. I’ve seen 3 trekkers get ‘rescued’ out of one group of 9 when all they needed was rest, fluid and maybe antibiotics for a gut infection. I’ve also seen someone with bad gastro enteritis who wasn’t insured having to be carried by horse for several days whilst having a very bad time of it and a guy with amoebic dysentery continuing up the trail, despite a senior British doctor trekker saying he must go down and get treated.
This is why we won’t take you if you are not insured.