Fitness & training
All expedition peaks are extremely demanding; requiring lots of willpower, tolerance of harsh conditions. You will need to be in excellent physical condition, be physically and mentally prepared to deal with strenuous situations at high altitudes. You are required to have past rock and steep snow climbing experience on exposed terrain and must be familiar with modern climbing techniques.
In order to build self confidence and develop experience on high altitude climbs we recommend that you gradually climb higher and higher peaks and have climbing experience at altitudes over 6,000m before attempting the world's highest peaks. Work on good aerobic fitness months before your expedition. The fitter you have been over the past several years, the better your chances.
Explore Himalaya also offers climbing course in conjunction with certified instructor which enable participants to develop high altitude experience and climbing skill. Please visit ‘climbing course’ section for more information.
Our Expedition Service
We have run 90 successful expeditions to 8000meter peaks in Nepal & Tibet either as a local operator for many top overseas companies or as a sole operator since our establishment in 1997.
We offer several different approaches: 1. Customized service for a private team, 2. Western guide-assisted climbs on fixed group departure dates, 3. Sherpa guide-assisted climbs, 4. Base camp only support and 5. ‘Permit only’ on full or sharing service.

• Customized Sevice: Our customized service for your private team is tailored to suit your exact requirements. We offer service of our expert Sherpa climbing guide, high altitude cook and other assistants as per your requirements. We arrange customs in Nepal, obtain permit from government, carry out all the necessary expedition logistics, book flight, hotel, arrange transportations etc.
• Western Guide: Our western guide-assisted service is usually coordinated and led by Jamie McGuinness (unless stated otherwise), our expedition consultant who has climbed many 6000m peaks and has summitted 8000m peaks more then ten times including Mt. Everest. He has proved to be a capable, caring organizer and very strong at altitude. We also organize climbs in conjunction with several other certified western guides on fixed group departure date. The expedition is supported by expert high Sherpa climbing guide, cook and porters, all meals are provided. Our administration team from office carries out all expedition logistics. This option of service is available on fixed departure dates, please check ‘2009 fixed departure’ section for availability.
• Sherpa Guide: Sherpa guide-assisted service is led by our Sherpa climbers who have created history in 8000 meter peaks climbing. The team in this service option is fully supported by assistant sherpas, cooks, porters and all meals provided. All expedition logistics are done by our administration team from office.

Base Camp Support Expedition
In this service option we provide cook, kitchen staff, kitchen, food and base camp/ABC tents for you at base camp and advanced base camp through out expedition period. This service is usually suitable for the team who does not require support during climb. In this service option you can also share expedition permit with available group. Please check us out for the availability.
Permit only service: If wish to relay on yourself for meals and climbing support, you can buy or share on expedition permit only. We can help you get your name listed on the expedition permit of then available group for a reasonable fee.
Meals & Logistic arrangement on our full supported climb
At the Base Camp, we provide three tasty, plentiful and nutritious meals daily with a variety of local and Western dishes. To start the day, breakfast consists of a choice of porridge, muesli and cereal followed by omelet, fried or scrambled eggs with chapattis or bread. Lunch is generally a selection of salad, cooked vegetable dishes, pasta and traditional breads. Dinner is a hearty 3 course meal - soup, followed by a variety of vegetable, meat, rice and pasta dishes and completed with a simple dessert. Tea, coffee and hot chocolate are also provided at all meals. We use as much fresh produce as possible and special diets are regularly catered for. The leaders are able to maintain very tight controls on health and hygiene in the kitchen with respect to general cleanliness and food preparation and also within the group with respect to personal hygiene. All foods are well cooked and vegetables are treated by potassium permanganate or iodine. Boiled water is served for drinking. Antiseptic soaps and potassium or iodine treated water are provided for washing. Special dietary requirements can always be catered for.
Administration team from office carry out all necessary logistics, such as getting climbing permit, help you get your expeditions goods through Nepal custom, arrange local transfers, book hotels, flight etc.
We allocate best climbing guide and assistants who have proven record in climbing high Himalayas, they speak reasonable amount of English, good enough to communicate with you on any matter.
Climbing seasons
Climbing can be done through out the year but later part of spring and September through November are more popular as weather and snow conditions are more stable and predictable. Winter climb is also getting popular among discerning climbers as snow conditions at this time gets relatively stable.

Environmental Consideration
At Explore Himalaya, we are extremely environmentally conscious and aim to minimize our impact as much as possible. As deforestation is one of greatest environmental threats, we do not have camp fires and use kerosene or LPG for cooking as an alternative fuel to wood. We also discourage trekkers/climbers from using wood-fuelled hot showers in lodges along the way. Our staff members are well motivated towards Eco-friendly practices. We bring back all our garbage from mountains, apart from that which can be safely and easily burnt at the campsite.
Medical supply / safety measures
You will need to get your own local medical advice about suitable inoculations and any prophylactics before departure. The major health concern is altitude related illness or Acute Mountain Sickness (AMS, DISCUSSED IN DETAIL UNDER ALTITUDE SICKNESS SECTION). All our high altitude treks/climbs are equipped with life saving equipments like Gammov Bag, Oxygen and a set of Medical kit as suggested in Dr. Jim Duff’s list of medicine for trekkers. Since our staffs/guides are not qualified for suggesting medications to western clients (in local guide assisted service), we would request you to use the medicines upon your own risk for your comfort, a printed verse of the standard manual stating the use of included medicines are made available in the medical kit. Principally it is safe and reliable if you have your own list of medicines supplied and so not depend on what we have.
Rescue/ Emergency Evacuation
In the case of a serious sickness or a casualty, which we believe will not happen; you shall be rescued by a helicopter. Since you are entirely liable for all the expenses incurred in evacuation please make sure that it is covered by your insurance before assigning for it or be prepared to pay on your own after getting back in Kathmandu. If you have no communication equipments, ask your guide to arrange a runner to the nearest communication point and inform office about requirement of a helicopter. While asking for the helicopter, you are required to send name of the sick person and exact location from where helicopter can airlift you. Do not leave the place although you are getting better once you have ordered helicopter.
Insurance
Your insurance is not included in our trip cost. We insure all our staff. Please ensure that you arrange your own insurance for emergency evacuation, personal effects, personal accident, medical travel expenses, baggage, cancellation etc.
Cost of the Trips
Cost and its inclusions and exclusions for our ‘fixed group departure’ trips are mentioned in each trip dossier. However, cost for private trip is fixed on the basis of group size, climbing fee as levied by government and service options as tailored to suit your requirement. You are required to outline your requirement and we make a confidential quote to you.
Meeting and airport transfers
Once you have decided to book any trip with us, you have to send us your flight details (name of Airlines arrival time and date). One of our Airport representatives and driver meet and greet you at the airport and drive you to your preferred hotel. After your trip is over you will be transferred back to the airport in time to catch your flight back home.
Accommodation in Kathmandu
In our fixed departure trips 5 nights accommodation is included at a conveniently located 3 star hotel in Kathmandu. If you are a private team with specific requirement we have specially negotiated rates a range of hotels, we can offer the best deal to suit your every budget and preference. Please check ‘HOTEL BOOKER’ section of this website for price and availability.
Booking/Payment/ Disclaimer
For booking procedure, payment option and disclaimer please see our ‘BOOKING CONDITION’ section and also visit ‘KNOW BEFORE YOU COME’ page for comprehensive information on Nepal.
Filming expedition
If you are planning on making a film of your Expedition, it is necessary to acquire a number of permits& authorizations. Here we have comprehensively outlined procedures to ensure a trouble free film- making during Expeditions. Generally, film making of an Expedition is considered as a documentary and there is no Fee levied for it however, Rs, 10,000 has to be paid as Sensor Fee. You can apply for making a film of the Expedition with following documents:
01. Filled Application form (Down Load)
02. Synopsis or script of the film
03. Bio Data of the members
04. Copy of Passports of each members
05. List of equipments to be imported for filming
06. Authorization letter to Explore Himalaya
Upon receiving above documents, Explore Himalaya shall process permission and acquire it before arrival of the Expedition
Communication equipments
Communication equipments like Sat Phones, VHF sets, Walkie Talkies, etc are quite often used in Expeditions. All these equipments require permits to be imported and used within the territory of Nepal. So, please follow following procedures to ensure that you are importing/using above equipments in a legal way. Following documents are required to make permit for communication equipments:
01. Filled Application Form (Down Load)
02. Specification of equipments
Once acquiring above papers, Explore Himalaya shall start the processing and get it approved. After approval, you are required to pay following fees for importing/using different communication equipments:
01. Walkie - Talkies up to 4 pcs – 20 USD per piece
02. Walkie - Talkies above 4 pcs – 30 USD per piece
03. Base Station – 200 USD per piece
04. Sat Phone (Iridium) – 2000 USD
05. Sat Phone (Inmarsat) – 2,500 USD
Since there are lots of Sat Phones (GSM system) available in Kathmandu these days, you can either buy or rent one in Kathmandu for the use of your Expedition. Explore Himalaya provides such Sat Phones on rent for US $ 15 per day but you have to pay separately for the call time. We request you to check with Explore Himalaya for the fresh price of rent and call charges.

Garbage management
The new amendment of Mountaineering Expedition Regulation, 2002 specifies certain terms and conditions to ensure that all your Expedition garbage is managed property according to norms and for this, you need to keep a deposit before leaving for the Expedition. Following deposit is applicable as a security against management of garbage which is refundable after expedition once you complete formalities ensuring proper disposal of your Expedition garbage:
Mt. Everest: US $ 4000
All 8000m Peaks: US $ 3000
All 7000m Peaks and Mt. Amadablam: US $ 2000
Peaks above 6500m: US $ 1000
Peaks below 6500m: US $ 500
For mountains below 8000m lying in the ranges other than Khumbu and Annapurna, garbage deposit shall be only US $ 500 as a special privilege
The materials to be considered as garbage can be obtained from schedule-10 (Down Load).
Deposit amount can be recovered after satisfying all the norms of garbage management as mentioned in Rule No. 27 of the Regulation (Down Load). As mentioned on the rule, garbage falling in the grade of ‘Recyclable’ can be deposited at SPCP office in Namche for Expeditions going to Khumbu and in Kathmandu in the office of Solid Waste Management for areas other than Khumbu.
Once you receive the certificate from these authorities against your garbage delivery and a statement from the Liaison officer stating about the management of your destroyable garbage, you are eligible to recover the garbage deposit. Although it looks very bureaucratic, pls. don’t panic, Explore Himalaya is there to work for you and you do not need to take any extra burden, you shall handle everything for you within the package.
Import/Export of expedition goods
IMPORT
Organization of a Mountaineering Expedition is definitely a big mission and in this, not everything required could travel together with you as an accompanying baggage. At times, there will be necessity to send your extra baggage, equipments, food stuffs and other materials through a special cargo either by Sea or Air. As your handling Agent, Explore Himalaya shall be happy to assist you and handle the import of such cargo containing Expedition stuffs. To make your cargo clearance easier and trouble free, it is important that you prepare your documents properly according to the norms of Nepalese government. So, we suggest you to follow following points while making the document.
01. Packing List
Please prepare packing list of Consumable and Re-exportable items separately. Items that are consumed during the Expedition like food material, medicines, gas, etc comes under ‘Consumable Items’. Items that are re-exported back to your country falls into this category like Tents, Equipments, Clothing items, etc. Separate lists should be prepared for ‘Consumable’ and ‘Re-exportable’ items mentioning their Individual & Total value. Please down load a sample list of ‘Consumable’ & ‘Re-exportable’ items coming as Expedition goods to Nepal.
02. Name of Consignee
On the ‘Name of Consignee’ section of your Air Way Bill, please mention the name of your Expedition under which you are issuing the permit of your Expedition. Under the name, our company name should follow as below:
Name of Consignee: ABC Expedition Team
C/O Explore Himalaya Travel & Adventure
745 Amrit Marg, Bhagban Bahal, Thamel
Kathmandu, Nepal.
P.O.B. 4902
Phone: 977 1 4418100, 4418400
Fax: 977 1 4412888

03. Final Permit
Before applying for recommendation with Ministry of Tourism to clear the cargo, it is necessary that you should have acquired the final permit. So, we suggest you to send final Royalty amount well before dispatching your Cargo.
04. Customs and duties.
According to regulations of Nepal government, you need to pay taxes like Customs, Vat, etc on goods imported for Expedition’s use. These are non refundable in case of Consumable and refundable in the case of Re-exportable items. Total charges of Tax comes something close to 25% of the CIF value is paid at the time of clearing it through customs. In case of Re-exportable goods, your tax is refunded once the goods exported are verified and deposited at the Custom’s Ware House.
Although it is mentioned 25% as Tax amount, there are number of hidden costs which is very difficult to explain. So, you are advised to spare around 30% of the goods value for the clearance of your Expedition goods.
Please check with us before sending the stuff, for any new information in this regard.
EXPORT
Anything that you need to export back to your country after completion of Expedition, we shall assist you in doing so. You can either dispatch it before leaving Kathmandu or leave it with us which we could send to your address later on. Price of the cargo varies upon which destination you are sending and what quantity of cargo we have. Please check with Explore Himalaya staff for any information in this regard.
PS: Please note that you need to acquire the filming and communication permits to import/export stuffs related to filming and communication. Please refer to information on Filming or communication section for the process related to acquiring of the permits.
Baggage allowance & ferry charge
Unlike in trekking and other cultural tours, Expedition Teams usually have extra baggage to be carried up to the Base Camp and back after completion of the Expedition. Usually, package price provided on per person basis provide baggage allowance up to 20-25 Kg which is usually enough for personal baggage only. Beside this, Explore Himalaya shall offer a package price for the baggage that exceeds your regular baggage allowance. Please check with us for extra baggage cost for the base camp of your choice.
Summit and Load Carry Bonus
In Mountaineering Expeditions, an unspoken rule is to reward your Sherpa Staffs for their hard work in helping members reach up to the summit of a peak. Although the name ‘Summit Bonus’ sounds like you need to pay it after making a successful ascent only, in some Expeditions, it is also paid to Sherpa staffs against each bag carried from the BC to higher camps. So, the system of Summit Bonus is different in Expeditions. For your reference, here are Two examples of summit bonus distribution
Summit Sherpas: US $ 750 each included Summit Bonus and Load Carrying Bonus
Non Summit Sherpas: US $ 300 and above included Load Carrying Bonus and other job
Example II: Summit Bonus: US $ 500 &
Load carrying bonus: from BC- C1------USD & then from C1 to C2 -------USD and so on, as per your budget.
Reserving a climbing sherpa
Referring to the growing number of Mountaineering Expeditions in Nepal and Tibet Himalaya each year, of course, there is always the scarcity of good, qualified and experienced Sherpa staffs. So, we suggest you to book your Sherpa staffs well in advance, at least a year before, if possible. Explore Himalaya shall help you to select and book the best lot of Sherpa staffs with good past record and experience on the peak that you are climbing.
Ice fall route (Everest & Lhotse only)
If you are planning to climb Mt. Everest from the South side and Lhotse from North using Ice fall route, it is necessary to pay a set fee against each member and Sherpa staffs for using the route across Ice Fall which is already prepared by some one else. Ice fall route for Spring 2009 is fixed.

Liaison officer
Every Expedition team climbing a peak over 6500m is subject to take a Liaison officer with them assigned by the Ministry of Tourism. These Liaison officers are supposed to go along with the Expedition Team up to Base Camp and stay through out. Activities of the Expedition Team is monitored by the Liaison officer who is also responsible for dispatching reports of Expedition's progress to the Ministry and also help the team for local coordination. Expedition team has to provide a full set of equipments as well as a daily allowance of Rs. 500 per day to the Liaison officer. The Team should also insure the Liaison officer against his accident and rescue evacuation.
Whatever is mentioned in the rules, it has been the tradition that Liaison officers prefer to receive their privileged for equipments and Salary in terms of a cash package. Ongoing amount for Liaison officer's package has been US $ 2000 in average. You are requested to check with Explore Himalaya for the latest going rate of LO's package.
Multiple permits
You can of course, receive permits for more than one peak at the same season. For receiving multiple permits, you need to pay separate Royalties for the peaks being permitted and also, separate Liaison officers for each peak assigned.
Expedition Briefing
Before departure of the Expedition, Expedition teams are required to present themselves at the Ministry for briefing. Your Liaison officer shall be introduced during the time of briefing. Leader of the Expedition can present at the Ministry for briefing and during his absence, Co-leader or a member of the team should present with a 'Power of Attorney' signed by the leader. Several forms need to be filled and submitted at the time of briefing which are as follows:
01. Insurance will form of the Nepalese Staffs – Schedule 7 (by Explore Himalaya)
02. Contract Form between the Team, Company and Staffs – Schedule 8
Debriefing
After completion of the Expedition, Leader of the Expedition Team has to again present himself at the ministry for de-briefing along with the Liaison officer. Expedition Report form – Schedule 8 has to be submitted at the Ministry during de-briefing.
Changing of members
If you have already received the preliminary permit, you have to report to the ministry at least 10 days before receiving the final permit if there is any change of members. Please send a copy of the new member's bio-date form to Explore Himalaya for this.
Support Group
While you are engaged in climbing of a mountain, it is possible that groups of people including your friends, families, etc. would like to make a Trek up to the Base Camp to visit and cheer your efforts. You could negotiate with Explore Himalaya for a special package to organize Support Treks for such groups.
Clothing & Equipment
Basically you should plan with 5 specific climates/functions in mind:

• 7000m and above
• Normal variable mountaineering conditions
• Intensely hot mountaineering conditions
• Base camp and ABC living
• travel-trekking to the mountain

Obviously much of your gear will fulfill multiple roles.
Travel-trek gear
You will use this gear from touchdown in Kathmandu to base camp. Obviously there is a lot of crossover; most of this gear can be used on the mountain too. Gear storage in Kathmandu is free so you can leave a clean set of clothes there, if you want.

•  Trekking pants and shirt
•  Thermal top
• fleece jacket
• Windproof, breathable jacket
•  Sleeping sheet for use in the not so clean hotels, silk is luxurious and great for using with your sleeping bag too

For the trek from BC to ABC be prepared for fine weather, wind and snow.

8000m gear

Conditions en route to the summit vary tremendously from day to day. You have to be prepared for the worst. It is essential to be fully insulated with down all over and to be fully wind-protected. With so little oxygen in the air you have trouble keeping warm, even while exercising. It is normal for a midnight start, and 8300m nights can be rather chilly to say the least.
Primaloft mittens: The best are the top of the range mitts from OR (Outdoor Research), Black Diamond, Mountain Hardwear etc, and all are normally available in Kathmandu. Ensure they have a system for looping around your wrist or can be attached to your down suit. Cheap bulky down mittens (good spares) are easily purchased in Kathmandu.
Down suit: You normally use a down suit from Camp 2/7000m to the summit, but nowhere else on the mountain unless conditions are particularly bad. Underneath it is normal to wear a mid-weight thermal top next to the skin, a stretch fleece (sleeveless) body suit over that and then an expedition weight thermal or 100 weight fleece over that. Down suits are preferable but if you go for down pants and down jacket ensure the waist area is well protected. The down jacket should be one of the thickest made. Down suits are now available in Kathmandu for less than $300. Some designs are better than others (we will show you the best) but all are serviceable.
Ski goggles: Clear goggles are very useful for Everest, to protect your eyes from the wind on that midnight start, and darker goggles can be useful climbing above North Col.
Water bottles and/or hydration system: You need to plan a system to keep in your down suit specifically for the summit attempt. If you have a system with tubes you MUST keep the tubes under your suit the whole time, only digging them out to drink, otherwise they will freeze, insulated tubes or not. Perhaps the safest system is 2x 0.5 litre (16oz) Nalgene bottles; they fit into chest pockets easily and are not as bulky and heavy as 1 liter bottles (because you are not carrying as much water, of course). These bottles are usually available in Kathmandu but bring from home if you are able to buy at home.
That is not a lot of fluid so many people prefer a camelback that goes under your down suit; be very careful with filling it and ensure the cap is screwed down properly.
 Boots: You need the warmest boots available. Generally the best are the Millet Everest (red and black in color) but the Lowe boots also look good. Thinsulate inner boots are NOT suitable, they can get wet. Please do discuss, boots are one of the most critical items. These boots, used and new, are usually available in Kathmandu for around US$500 or less. They are surprisingly light and extremely warm but a bit clumsy. It is normal to use them above ABC. The boots should fit well but not tight as your feet can swell at altitude. Don't get boots two sizes too big.
ENSURE YOUR CRAMPONS FIT whichever system you are using.

Socks:  2x brand new thick socks for the summit attempt, these should be mainly wool. One pair for using, one for backup.

Foot warmers: There are more and more solutions to help keep your feet warm. It is unusual to get frostbite in good boots but you feel the cold.

Summit day pack: This should be very light but capable of carrying nearly 8 kgs of oxygen - or use the pack for carrying gear up to the last camp.

BC/ABC evening gear
Around base camp and ABC you can wear camp shoes or leather boots. Although climbing boot inners are warm, the sharp rock underfoot trashes them.

• Substantial down jacket.
• Thick fleece pants or Primaloft pants (Mountain Hardwear Chugach pants are popular).
• BC sleeping bag. This should be 4 season although a fleece lining (available in Kathmandu) can do wonders. It saves you a lot of ferrying if you have two sleeping bags, one for BC and another for ABC (for Interim camp we will move your BC bag back). You can get serviceable sleeping bags in Kathmandu for US$200-300, and boost it with a quilt or duvet over the top.
• Sleeping bag liner.
• ABC Thermarest we provide a combined closed cell and open cell mattress for BC and ABC but a Thermarest adds warmth at ABC.
• BC and ABC pee bottle

What is available in Kathmandu?
It's not necessary to spend a lot of money buying extra equipment and clothing before your trip. Majority of these gears can be bough or hired at reasonable rates in Kathmandu. Explore Himalaya owns a gear shop in Kathmandu selling and renting out climbing and trekking gears, both Nepali made and original. Please check out www.trekkinggearsnepal.com  .
ACCLIMATIZATION AND ALTITUDE SICKNESS
Acute Mountain Sickness or AMS  
Commonly called altitude sickness, this has the potential to affect all trekkers from 2500m and higher. Your body needs days to adjust to smaller quantities of oxygen in the air - at 5500m/18,044ft the air pressure is approximately half that of sea level, ie there is half the amount of oxygen (and nitrogen). This is approximately equivalent to the top of Kala Pattar, in the Everest region, and the top of the Thorung La on the Annapurna Circuit.
For treks below an altitude of about 3000m/10,000ft it is not normally a problem. AMS is caused by going up high too fast and can be fatal if all the warning signals are ignored. Note that it is not the actual altitude, but the speed at which you reach higher altitudes which causes the problems.
Altitude sickness is preventable. Go up slowly, giving your body enough time to adjust. These are the 'safe' rates for the majority of trekkers: spend 2-3 nights between 2000m/6562ft and 3000m/10,000ft before going higher. From 3000m sleep an average of 300m/1000ft higher each night with a rest day every 900-1000m/3000ft.Ultimately it is up to you to recognise the symptoms, and only ascend if you are relatively symptom-free.

Normal symptoms at altitude

Don't expect to feel perfect at altitudes of more than 3000m. These are the normal altitude symptoms that you should expect BUT NOT worry about. Every trekker will experience some or all of these, no matter how slowly they ascend.
Periods of sleeplessness
The need for more sleep than normal, often 10 hours or more
Occasional loss of appetite
Vivid, wild dreams at around 2500-3800m in altitude
Unexpected momentary shortness of breath, day and night
Periodic breathing that wakes you occasionally - consider taking Diamox
The need to rest/catch your breath frequently while trekking, especially above 4000m
Your nose turning into a full-time snot factory
Increased urination - many trekkers have to go once during the night (a good sign that your body is acclimatizing:

Mild Symptoms

You only need to get one of the symptoms to be getting altitude sickness, not all of them.
Headache - common among trekkers. Often a headache comes on during the evening and nearly always worsens during the night.Raising your head and shoulders while trying to sleep sometimes offers partial relief. If it is bad you may want to try taking a painkiller: aspirin (dispirin), paracetamol, Ibuprofen (Aduil) or acetamenophen (tylenol). Never take sleeping tablets. You could also take Diamox: see below. Headaches arise from many causes, for example, dehydration, but if you develop a headache assume it is from the altitude.
Nausea (feeling sick) - can occur without other symptoms, but often nausea will develop with a bad headache. If you are better in the morning take a rest day, or if you still feel bad descend.
Dizziness (mild) - if this occurs while walking, stop out of the sun and have a rest and drink. Stay at the closest teahouse.
Lack of appetite or generally feeling bad - common at altitude due to too rapid an ascent.
Painful cough or a dry raspy cough.
In other words anything other than diarrhoea or a sore throat could be altitude sickness. Assume it is, because if you have a headache from dehydration, ascending further is not dangerous, but if its due to AMS, the consequences could be very serious. You cannot tell the difference, so caution is the safest course.
Do not try to deceive yourself and accept that you body needs more time to adapt.

Basic rule: NEVER GO HIGHER WITH MILD SYMPTOMS

If you find mild symptoms developing while walking, stop and relax with your head out of the sun and drink some fluids. If the symptoms do not go away completely then stay at same altitude. Or if symptoms get worse, GO DOWN. A small loss of elevation (100-300m/328-984ft) can make a big difference to how you feel and how you sleep - descend to the last place where you felt good. If symptoms develop at night then, unless they rapidly get worse, wait them out and see how you feel in the morning. If the symptoms have not gone after breakfast then have a rest day or descend. If they have gone, consider having a rest day or an easy days walking anyway.
Continued ascent is likely to bring back the symptoms. Altitude sickness should be reacted to, when symptoms are mild - going higher will definitely make it worse. You trek to enjoy, not to feel sick.
Note also that there is a time lag between arriving at altitude and the onset of symptoms and in fact it is common to suffer mild symptoms on the second night at a set altitude rather than the first night.

Serious Symptoms

Persistent, severe headache.
Persistent vomiting
Ataxia - loss of co-ordination, cannot walk in a straight line, looks drunk
Losing consciousness - cannot stay awake or understand things very well
Liquid sounds in the lungs
Very persistent cough
Real difficulty breathing
Rapid breathing or feeling breathless at rest
Coughing blood or pink goo or lots of clear fluid
Marked blueness of face and lips
High resting heart beat - over 120 beats per minute
Severe lethargy and drowsiness
Mild symptoms rapidly getting worse
Ataxia is the single most important sign for recognising the progression from mild to severe. This is easily tested by trying to walking a straight line, heel to toe. Compare with somebody who has no symptoms. 24 hours after the onset of ataxia a coma is possible, followed by death, unless you descend.

Basic rule: IMMEDIATE AND FAST DESCENT WITH SEVERE SYMPTOMS

Take as far down as possible, even if it is during the night. (In the Everest region: if you are above Pheriche, go down to the HRA post there. From Thorung Phedi or nearby: take to the Manang HRA post.) The patient must be supported by several people or carried by a porter - his/her condition may get worse before getting better. Later the patient must rest and see a doctor. People with severe symptoms may not be able to think for themselves and may say they feel OK. They are not.

Medical Conditions

High Altitude Cerebral Oedema (HACE) - this is a build-up of fluid around the brain. It causes the first 4 symptoms of the mild, and the severe symptom lists.
High Altitude Pulmonary Oedema (HAPE) - this is an accumulation of fluid in the lungs, and since you are not a fish, this is serious. It is responsible for all the other mild and serious symptoms.
Periodic breathing - the altitude affects the body's breathing mechanism. While at rest or sleeping your body feels the need to breathe less and less, to the point where suddenly you require some deep breaths to recover. This cycle can be a few breaths long, where after a couple breaths you miss a breath completely, to being a gradual cycle over a few minutes, appearing as if the breathing rate simply goes up and down regularly. It is experienced by most trekkers at Namche, although many people are unaware of it while sleeping. At 5000m/16,404ft virtually all trekkers experience it although it is troublesome only for a few. Studies have so far found no direct link to AMS.
Swelling of the hands, feet, face and lower abdomen - remove rings. An HRA study showed that about 18% of trekkers have some swelling, usually minor. Females are definitely more susceptible. It is not a cause for concern unless the swelling is severe, so continuing ascent is OK.
Altitude immune suppression - at base camp altitudes cuts and infections heal very slowly so for serious infections descent to Namche level is recommended. The reasons are not well understood.

Drugs you can take - Diamox (Acetazolamide)

This is a mild diuretic (makes you pee a lot) that acidifies the blood which stimulates breathing. Previously it was not recommended to take it as a prophylactic (ie to prevent it, before you get it) unless you ascend rapidly, unavoidably (eg flying to Lhasa or rescue missions), or have experienced undue altitude problems previously.
However, now some doctors are coming around to the idea that many people trekking above 3500m should take it using the logic that it has the potential to reduce the number of serious cases of AMS: the benefits may outweigh the risks. This topic still requires in depth research. Diamox is a sulfa drug derivative, and people allergic to this class of drugs should not take Diamox. People with renal (kidney) problems should avoid it too. (It also apparently ruins the taste of beer and soft drinks). The side effects are peeing a lot, tingling lips, fingers or toes but these symptoms are not an indication to stop the drug.
The older accepted recommendations are to carry it and consider using it if you experience mild but annoying symptoms, especially periodic breathing that continually wakes you up. The dosage is 125 to 250 mg (half to a whole tablet) every 12 hours. Diamox actually helps the root of the problem; so if you feel better, you are better. It does not simply hide the problem. However this does not mean that you can ascend at a faster rate than normal, or ignore altitude sickness symptoms - it is quite possible still to develop AMS while taking it. Note that it was recommended to start taking the drug before ascending for it to be most effective. This is not necessary, but it does help.

Doctors Notes

HACE - can occur in 12 hours but normally 1-3 days. At first sign of ataxia begin descent. If it is developed try 4mg of dexamethazone 6 hourly, Diamox 250mg 12 hourly and 2-4l/min O2 or a Gamow bag (if available).
HAPE - descend, Diamox 250mg 12 hourly, Nifed orally, 10mg 8 hourly and 2-4l/min O2 or a Gamow bag.
Oxygen - supplementary O2 does not immediately reverse all the symptoms although it does help significantly. Descent in conjunction with O2 is more effective.
Gamow bag/ PAC bag/CERTEC bag - the latest devices to assist with severe AMS. Basically it is a plastic tube that the patient is zipped into. A pump is used to raise the pressure inside the bag simulating going to a lower altitude. It is very effective.
HAF - high altitude farts - slang for HAFE.
HAFE - high altitude flatulence emission. The cure - let it rip! You're not a balloon that needs blowing up.
AMS practicals

Rates of acclimatization

Individual rates of acclimatization vary enormously but ascending very rapidly and staying there will ALWAYS result in problems. Even Sherpas who live in Kathmandu upon returning to the Khumbu occasionally get AMS. Studies have shown that people who live at moderate altitudes (1000-2000m/3281-6562ft are acclimatized to those altitudes. They are much less susceptible to AMS when ascending to around 3000m/9842ft (ie going to Namche).
However the benefits decrease once higher and they should follow the same acclimatization program as others. This has implications for people who have spent a week or two in Kathmandu (at an altitude of 1400m/4593ft): they are becoming acclimatized to that altitude. For trekkers that fly from sea level to Kathmandu then almost immediately walk to Namche, they have no advantage and are more likely to suffer AMS. Unfortunately it is usually these people who are in a hurry to go higher. This is perhaps why it appears that group trekkers are initially more susceptible to troublesome AMS than individual trekkers, who often walk from Jiri or spend time in Kathmandu beforehand.

The Acclimatization Process

In a matter of hours your body quickly realises that there is less oxygen available and it first reaction is to breathe more - hyperventilate. This means more oxygen (O2) in but also more carbon dioxide (CO2) is breathed out and with the O2-CO2 balance upset the pH of the blood is altered.
Your body determines how deeply to breathe by the pH level (mainly the dissolved CO2 in your blood) - at sea level a high level of exertion means your muscles produce a lot of CO2 so you breathe hard and fast. While resting, your body is using little energy so little CO2 is produced, demonstrating that you only need to breathe shallowly.
The problem is at altitude this balance is upset and your body often believes that it can breathe less than its real requirements. Over several days your body tries to correct this imbalance by disposing of bicarbonate (CO2 in water) in the urine to compensate, hence the need to drink a lot because it is not very soluble. Diamox assists by allowing the kidneys to do this more efficiently therefore enhancing some peoples ability to acclimatize. In addition, after a day or two, the body moves some fluid out of the blood effectively increasing the haemoglobin concentration. After 4-5 days more new red blood cells are released than normal.
Individual rates of acclimatization are essentially dependent on how fast your body reacts to compensate the altered pH level of the blood. For slow starters Diamox can provide a kick-start but for people already adapting well the effect often less noticeable.
If you stay at altitude for several weeks there are more changes, your muscles' mitochondria (the energy converters in the muscle) multiply, a denser network of capillaries develop and your maximum work rate increases slowly with these changes. Expeditions have often run medical programs with some interesting results.
Climbers who experience periodic breathing (the majority) at base camp never shake it off and have great difficulty maintaining their normal body weight. Muscles will strengthen and stamina is increased but not the muscle bulk. Interestingly Sherpas who have always lived at altitude, never experience periodic breathing and can actually put on weight with enough food.

How long does acclimatization last?

It varies, but if you were at altitude for a month or more your improved work rates can persist for weeks meaning you still feel fit upon returning to altitude. You still should not ascend faster than normal if you return to sea level for a few days, otherwise you are susceptible to HAPE.
If you have been to 5000m/16,404ft then go down to 3500m/11,483ft for a few days, returning rapidly to 5000m/16,404ft should cause no problems, ie having been to Lobuche and Kala Pattar, then rested for two days in Namche you should be able to ascend to Gokyo quickly without problems.

Sleeping at altitude

Many people have trouble sleeping in a new environment, especially if it changes every day. Altitude adds to the problems. The decrease of oxygen means that some people experience wild dreams with this often happening at around 3000m. Compound this with a few people suffering from headaches or nausea, a couple of toilet visits, a few snorers and periodic breathers, and it takes someone who sleeps like the proverbial log (or very tired trekker) to ignore all the goings on at night in a large dormitory. Smaller rooms are a definite improvement, and tents, although not soundproof are still manage to be relatively peaceful.

Appetite

Some people lose appetite and do not enjoy eating. Sometimes equally worrying, although it is a good sign, is a huge appetite. Your energy consumption, even at rest is significantly higher than normal because your body is generating heat to combat the constant cold, especially while sleeping. Energetic trekkers, no matter how much they eat will often be unable to replace the huge quantities of energy used.

Day trips and what to do if...

The normal accepted recommendations are to go high during the day and sleep low at night, the sleeping altitude being the most important. This is fine for trekkers experiencing no AMS symptoms whatsoever, and will probably aid the acclimatization process, for example in the Everest region, going up to Chukhung from Dingboche or Pheriche, or visiting Thame from Namche. However if you are experiencing mild or even very mild AMS then this is not the best advice. Instead your body is already having trouble coping so it doesn't need the additional stress of more altitude. Instead stay at the same elevation. Mild exercise is considered beneficial, rather than being a total sloth but take it as a rest day.
If you have troublesome mild symptoms then descent for a few hours may even be more beneficial.
Following information on AMS is prepared by Jamie McGuinness with the help of a doctor.
Jamie McGuinness is Explore Himalaya's expedition consultant and 8000 meter peak climbing leader. He has been trekking and climbing in the Himalayas since 1988 and has written several guide books on Nepal and has summitted 8000m peaks more then ten times including Mt. Everest since 1999.