Altitude Sickness During Everest Base Camp Trek

Altitude sickness during the Everest Base Camp trek is common because the route takes trekkers rapidly from 1,400 meters in Kathmandu to over 5,300 meters in less than 10 days. This speed of ascent, combined with cold, dehydration, and fatigue, is the reason many first-time trekkers struggle despite being physically fit.

This is also the reason why 60% of beginners fail to complete the trek, not because they are weak, but because altitude is misunderstood. Furthermore, it is one of the major reasons behind the perception of Everest base camp being dangerous.

Quick Summary

• Altitude sickness is common on the Everest Base Camp trek, affecting an estimated 30–50% of trekkers.
• Most symptoms begin after Namche Bazaar due to the rapid altitude gain from Lukla.
• Oxygen availability at Everest Base Camp is roughly 50% lower than at sea level.
• Licensed guides reduce altitude risk by controlling pace, managing acclimatization, and detecting early symptoms.
• Many Everest Base Camp evacuations can be prevented with proper acclimatization and planned rest days.

Everest Base Camp Trek Overview

Understanding the route, villages, and altitude profile of the Everest region helps explain why altitude sickness behaves differently here than on lower treks in Nepal.

Everest Base Camp Trek, commonly known as the EBC trek, is one of the most renowned trekking destinations in the world and a dream destination for many travelers around the globe. Every year, thousands of visitors come to the base camp to witness the world’s highest mountain with their own eyes.

The stunning views of Mount Everest from Everest Base Camp and the sunrise view from Kalapatthar are beyond imagination. This place is like paradise and will remain in your memories throughout your life.

If you are a trekking enthusiast and have a strong determination for trekking, then Everest Base Camp will be your perfect destination. This palace not only offers a magnificent view of the towering mountain, but also allows you to immerse yourself in the culture and tradition of the local Sherpa people.

Also, enjoying the warm hospitality and spending the night in cozy tea houses, escaping from the regular lifestyle, will relieve stress and transport you to another world filled with nature and beautiful landscapes.

However, even during the best season for trekking to Everest Base Camp, there is one hidden risk: altitude sickness, which is why, today in this blog, we are going to discuss in detail this risk.

Oxygen Levels on the Everest Base Camp Trek (Why Does Altitude Sickness Happen In EBC)

As altitude increases, oxygen availability drops sharply, even though the percentage of oxygen in the air remains the same. What changes is air pressure, which directly affects how much oxygen your lungs can absorb.

Here’s what that means on the Everest Base Camp route:

By the time you reach Everest Base Camp, your body is operating with roughly half the oxygen it is used to at sea level. This is why simple tasks like sleeping, eating, or even putting on boots can feel exhausting. It is also why symptoms often worsen at night, when breathing naturally slows.

Understanding this oxygen reality helps trekkers recognize early warning signs and explains why guides emphasize rest days, hydration, and controlled ascent rather than pushing mileage.

How Common Is Everest Base Camp Altitude Sickness?

According to our internal data, we found that 6 out of 10 trekkers experience symptoms of altitude sickness during the EBC trek. In fact, when we looked closely, we found out that altitude sickness was particularly common in more difficult treks like the Everest Three Passes trek and the Gokyo Lake Trek. On the other hand, the risk was minimal during the Pikey Peak Trek and the Everest View Trek.

However, through our research, we also came to the conclusion that only half of them were fully aware of what altitude sickness really is.

First, let’s provide you with a brief overview of altitude sickness.

Altitude sickness, often known as mountain sickness, happens when your body does not have enough time to acclimate to decreasing oxygen levels at higher elevations.

It can happen if you climb to higher elevations too soon. As you ascend, your oxygen levels decrease. When you have altitude sickness, every breath you take may feel more difficult because of the reduced oxygen levels.

In fact, according to the Cleveland Clinic, trekkers who ascend to 3,352 meters quickly will experience symptoms of AMS.

When we talk about altitude sickness during the Everest Base Camp trek, the chances are high because this trek takes you to the maximum altitude of 5,364 meters (17,598 feet) at Everest Base Camp. If you reach further for the sunrise view at Kala Patthar, then it takes you to an altitude of 5,644 m.

Altitude sickness is divided into three major categories;

Acute mountain sickness (AMS):

AMS is generally known as the initial stage of altitude sickness, which is common and can be cured easily.

High Altitude Pulmonary Edema (HAPE):

When the AMS becomes more severe, it can lead to HAPE. In this stage, your lungs will be affected, which causes them to fill with fluid. Immediate medical treatment is required in this situation. If not cured in time, it can be fatal, and sometimes it can also cause death.

High Altitude Cerebral Edema (HACE):

Another severe form of altitude sickness is HACE, which causes your brain to swell. During this stage, if not treated immediately, it can lead to dangerous situations and even death.

Note: The first thing that trekkers should understand is that when they experience symptoms of AMS (Acute Mountain Sickness), they need to take care of their bodies immediately. If not treated promptly, it can lead to dangerous situations, which nobody expects to happen during the Everest Base Camp trek.

Below is how altitude sickness typically presents itself by location along the Everest Base Camp trail, and why each place matters.

Lukla (2,846 m) – Low Risk, First Adjustment Zone

At Lukla Airport, oxygen availability drops to about 72% of sea level. Most trekkers feel fine here, but mild symptoms such as shortness of breath while walking uphill or restless sleep can occur.

• Common issues: Mild headache, increased breathing
• AMS likelihood: Low (under 10%)
• Why: The body is still adapting, and exertion is limited

Problems at Lukla usually come from rapid ascent by flight, not altitude sickness itself, which is why guides slow the pace immediately after arrival.

Namche Bazaar (3,440 m) – AMS Becomes Noticeable

Namche is where altitude sickness first becomes clinically relevant. Oxygen availability drops to around 65%, and trekkers arrive after two days of walking.

• Common issues: Headache, poor sleep, loss of appetite
• AMS likelihood: 20–30%
• Why: First major altitude jump combined with physical exertion

This is why a mandatory acclimatization day is built into every standard itinerary. Trekkers who skip or rush this stage account for a large portion of early turnbacks.

Dingboche (4,410 m) – Highest AMS Risk Zone

Dingboche is the most critical point for Acute Mountain Sickness on the entire trek.
Oxygen availability here drops to approximately 58%, and nights become significantly colder.

• Common issues: Persistent headache, nausea, fatigue, sleep disturbance
• AMS likelihood: 30–40%
• Why: Sustained altitude exposure combined with reduced nighttime oxygen saturation

Most cases of moderate AMS develop here. Trekkers who ignore symptoms at Dingboche often worsen quickly as they go higher.

This is also where guides become stricter about pacing, hydration, and rest.

Lobuche (4,940 m) – Transition Zone for Severe Illness

At Lobuche, oxygen availability falls to around 54%, and physical recovery slows noticeably.

• Common issues: Shortness of breath at rest, chest tightness, worsening fatigue
• HAPE risk: Begins to appear (around 1%)
• Why: Fluid retention increases in cold, thin air, stressing the lungs

HAPE rarely starts suddenly. It often builds from ignored AMS symptoms lower on the trail.

Gorak Shep (5,164 m) – Peak Risk for HAPE and HACE

Gorak Shep is the most dangerous overnight location on the Everest Base Camp trek. Oxygen availability drops to about 52%, and sleep quality declines sharply.

• Common issues: Severe headache, confusion, breathlessness at rest
• HAPE/HACE risk: Highest on the trek (combined 1–2%)
• Why: Extreme altitude, cold temperatures, and exhaustion converge

Most emergency evacuations for altitude sickness originate from Gorak Shep or shortly after leaving it. This is why experienced guides limit time here and monitor trekkers closely.

Everest Base Camp (5,364 m) – Short Exposure, Lower Risk Than Expected

Although Everest Base Camp sits at the highest altitude, serious altitude sickness is less common here than at Gorak Shep.

• Why: Trekkers do not sleep at Base Camp
• Risk factor: Overexertion, dehydration, lingering AMS

Most symptoms at Base Camp are fatigue-related, not new altitude illness.

Kala Patthar (5,644 m) – Exertion Risk, Not Altitude Illness

Kala Patthar reaches higher than Everest Base Camp, but exposure is brief.

• Main risk: Dizziness and breathlessness during ascent
• Why: Physical effort at very low oxygen levels (50%)

Descending immediately after sunrise minimizes risk.

However, the fact is that hiring a guide and a porter during the EBC trek does significantly reduce the risk. In fact, they even help you deal with other physical injuries in the Everest base camp.

Why Trekking With a Licensed Guide Significantly Reduces Altitude Risk

Altitude sickness on the Everest Base Camp trek is rarely caused by a single mistake. In most cases, it develops because early warning signs are missed or ignored, especially among first-time EBC trekkers who have never experienced high altitude.

This is where a licensed trekking guide makes a measurable difference.

Experienced guides in the Everest region do not wait for trekkers to say they feel unwell. They watch for subtle changes that many beginners overlook, such as a slower walking pace, unusual silence, loss of appetite, shallow breathing at rest, or repeated headaches late in the day. These signs often appear hours before trekkers recognize them as altitude sickness.

Guides also control pacing and daily altitude gain, even when trekkers feel strong. Many cases of AMS occur not because the trek is hard, but because people walk too fast on “easy days” like Namche to Tengboche or Dingboche to Lobuche. A guide slows these days deliberately, reducing stress on the body.

Another critical role of guides is decision-making under pressure. Beginners often hesitate to descend because of time, money, or fear of failure. Guides remove that emotional burden by making objective calls based on symptoms, not motivation. This early intervention is one of the main reasons evacuation rates are lower for guided trekkers.

In serious cases, guides are trained to coordinate oxygen support, descent logistics, and helicopter evacuation, which is often the difference between a controlled situation and a medical emergency.

For this reason, trekking with a licensed guide is not about convenience. It is one of the most effective ways to reduce altitude-related risk on the Everest Base Camp route, especially for beginners.

Symptoms of Acute Mountain Sickness (AMS)

• Headache 
• Nausea and vomiting.
• Loss of appetite.
• Fatigue, even when resting.
• Malaise (a noticeable “unwell” feeling).
• Trouble sleeping.
• Dizziness or lightheadedness.

Preventive measures of altitude sickness 

1. Gradual Ascent: Take your time ascending to higher altitudes, allowing your body to adjust slowly.
2. Stay Hydrated: Drink plenty of fluids to stay hydrated, but limit alcohol and caffeine intake.
3. Acclimatization Days: Plan rest days at higher elevations to give your body time to adapt.
4. Recognize Symptoms: Learn the signs of altitude sickness and respond promptly if they occur.
5. Proper Nutrition: Maintain a balanced diet rich in carbohydrates and low in fats to fuel your trek.
6. Sun Protection: Use sunscreen, wear sunglasses, and cover exposed skin to shield against UV rays.
7. Stay Warm: Dress in layers to stay warm and protect against cold temperatures at higher altitudes.
8. Avoid Tobacco and Alcohol: Both can exacerbate altitude sickness, so it’s best to avoid them during your trek.
9. Travel with a Guide: Consider hiring a knowledgeable guide for support and guidance along the journey.
10. Listen to Your Body: Pay attention to how you’re feeling and don’t hesitate to descend if symptoms worsen.
11. Start Your Preparation Early: Altitude preparation begins weeks before the trek, not days. This includes pacing plans, hydration habits, and understanding when to stop ascending even if the itinerary says otherwise.

If you understood these measures fully, then it’s time to give us your information, and we will start booking your Kathmandu to Lukla Flight.

Frequently Asked Questions(FAQs)

Can I get altitude sickness during the Everest Base Camp trek?

Yes, since you will be trekking above 5000m during the Everest Base Camp trek, the risk of Altitude sickness increases significantly.

What kind of measures will Eco Nepal Trekkers take to reduce the risk of Altitude sickness?

At Eco Nepal Trekkers, our primary goal is to ensure the safety of our travelers in all conditions. To keep you safe, we provide you with experienced and well-trained guides who monitor your progress throughout each day of the trek. Furthermore, even during the trek, they keep an eye on you to see if any symptoms arise.

Should I take Diamox on the Everest Base Camp trek?

Many people start taking Diamox right at the beginning of their trip and keep taking it until they return to their starting point. Others might choose not to take it initially, but start if they start feeling sick or if their guide suggests it.

What to do if I get altitude sickness during the Everest Base Camp trek?

The first thing you need to understand is that the initial symptoms of altitude sickness can be cured easily by ascending to a lower altitude. If you experience symptoms of altitude sickness, it’s important to inform your trekking guide. They will assist you and guide you to a lower altitude for treatment.

Does Diamox cure altitude sickness?

Taking Diamox before starting the trek is considered a preventive measure against altitude sickness. However, after you get altitude sickness, Diamox will not help.

Can I buy Diamox in Kathmandu?

You don’t need a doctor’s prescription to purchase Diamox. You can easily buy from the pharmacy in Kathmandu, Lukla, and even in Namche Bazar. However, if you have pre-existing conditions, we advise you to consult your doctor first. 

Can a normal person climb to Everest Base Camp?

As long as you are physically fit and fine, you can climb the Everest base camp trek. Make sure to engage in cardiovascular training and strength training, and learn how to deal with altitude sickness before joining the Everest Base Camp Trek.

What percentage of people make it to Everest Base Camp?

According to the data and survey, it is believed that around 90% of trekkers have successfully climbed the Everest Base Camp Trek. It is made possible with the help of an expert guide and the contribution of a porter during the trek. Therefore, we suggest you always go through registered trekking agencies to make your journey smooth, successful, and comfortable.

How to book the Everest Base Camp trek?

For booking the Everest base camp trek, you can fill out the form for the related package, and after filling out the form, you can submit it to us. You can also message us on WhatsApp for bookings or if you need any assistance with trekking. Our WhatsApp number is +977-9813322433.

Final Say

If you are planning the Everest Base Camp trek, make sure to travel in the best seasons of spring and autumn. Also, be prepared with physical and mental fitness, with an understanding of altitude sickness. 

This iconic place is on the bucket list of many travelers, and the memories that you will make during the trip to the Everest base camp trek will remain in your memories forever. With proper planning and preparation, and with the assistance of registered trekking agencies, you will be well-equipped to tackle the trek. Have a great day!