Mardi Himal is often described as a short, moderate trek, and that is accurate. But short does not mean low. In two or three days you climb from Pokhara at around 820 meters to High Camp at 3,580 meters, and on the Base Camp hike you reach roughly 4,500 meters, higher than any point in the Alps. That combination of speed and height means altitude sickness is the health issue every Mardi Himal trekker should understand before setting off.
The good news is that altitude sickness on this route is usually mild and manageable, and the ridge makes it easy to lose height quickly if needed. This guide explains how altitude affects the body, the symptoms to watch for, how to prevent problems and what to do if they happen. It is general information rather than medical advice, so speak to your doctor if you have any health conditions or questions about medication.
What Altitude Sickness Is
As you go higher, the air pressure falls and each breath carries less oxygen. At High Camp there is roughly a third less oxygen available per breath than at sea level. Your body responds by breathing faster, increasing your heart rate and, over several days, producing more red blood cells. This process is called acclimatization. Altitude sickness happens when you climb faster than your body can adjust.
There are three forms. Acute mountain sickness (AMS) is common and usually mild, feeling like a hangover. High altitude pulmonary edema (HAPE), fluid in the lungs, and high altitude cerebral edema (HACE), swelling of the brain, are rare but serious. Our guide to recognising AMS, HAPE and HACE covers the warning signs in more depth.
Where Altitude Matters on the Mardi Himal Trek
| Stop | Altitude | Altitude risk |
|---|---|---|
| Pokhara | 822 m | None |
| Pitam Deurali | 2,100 m | Very low |
| Forest Camp | 2,600 m | Low; occasional mild headache |
| Low Camp | 2,970 m | Mild symptoms possible |
| High Camp | 3,580 m | Mild to moderate symptoms fairly common |
| Base Camp (day visit) | About 4,500 m | Breathlessness universal; symptoms possible |
The key point is that you sleep no higher than 3,580 meters. Your body only spends a few hours above that, on the Base Camp hike, before descending. This "climb high, sleep low" pattern is why most trekkers cope well. Read how high Mardi Himal Base Camp really is for more on what 4,500 meters feels like.
Symptoms to Watch For
Mild AMS
- Headache, often throbbing and worse when lying down
- Loss of appetite or nausea
- Tiredness beyond what the day's walking explains
- Dizziness or light-headedness
- Poor sleep, sometimes with irregular breathing at night
Mild AMS often appears in the evening after arriving at a new altitude and improves overnight. It is common at High Camp. Tell your guide about any headache so they can keep an eye on you.
Warning Signs of HAPE and HACE
- Breathlessness at rest, not just when walking uphill
- A persistent cough, sometimes with frothy or pink sputum
- Severe headache that does not respond to painkillers
- Confusion, unusual behaviour or drowsiness
- Loss of coordination, such as stumbling or being unable to walk in a straight line
These are medical emergencies. The treatment is to descend immediately, with help, and seek medical care. Serious cases on Mardi Himal are rare, but knowing the signs matters because the person affected often does not recognise them.
Why Mardi Himal Needs Respect Despite Its Height
Many trekkers underestimate Mardi Himal because it is not a very high trek compared with Everest Base Camp. The real issue is speed. The standard advice for trekking above 3,000 meters is to increase your sleeping altitude by no more than about 300 to 500 meters per night. On most Mardi Himal itineraries you gain more than that on at least one day, especially from Low Camp or Forest Camp to High Camp. On the 3-day version you climb from Pokhara to Low Camp on the first day.
These itineraries still work for most people because the maximum sleeping altitude is modest and the high point is visited briefly. But they leave less margin for error than a slower trek, so paying attention to how you feel matters. Our guide to acclimatization on Mardi Himal explains how each itinerary handles altitude.
How to Prevent Altitude Sickness
Choose a Sensible Itinerary
The biggest single factor is your itinerary. The 5, 7 and 9-day versions build in an extra night lower down before High Camp, which gives your body more time. If you have never been above 3,000 meters, avoid the fastest 3-day version unless you are fit and willing to turn back. Our day-by-day itinerary guide compares the versions.
Walk Slowly
Nepali guides have a phrase for it: "bistarai, bistarai", meaning slowly, slowly. A slow, steady pace on the climbs keeps your breathing and heart rate under control and reduces the strain on your body. If you cannot hold a conversation while walking uphill, you are going too fast.
Drink Plenty of Water
Dry mountain air and hard breathing dehydrate you faster than at home. Aim for three to four liters of fluid a day, including tea and soup. Dehydration does not cause altitude sickness, but it makes headaches worse and can make it harder to tell what is going on. See hydration on the Mardi Himal Trek.
Eat Well and Avoid Alcohol
Carbohydrate-rich meals such as dal bhat, rice, potatoes and noodles are easy to digest and fuel your body well at altitude. Avoid alcohol and sleeping pills above Low Camp, as both can depress breathing during sleep.
Keep Warm
Cold adds stress to the body. Change out of sweaty clothes as soon as you arrive at each camp, and wear a hat and warm layers in the evening.
Be Honest with Your Guide
Your guide has seen altitude sickness many times and knows what to look for. The most dangerous thing a trekker can do is hide symptoms to avoid slowing the group. Tell your guide about any headache, nausea or unusual tiredness, however small.
Diamox and Other Medication
Acetazolamide, commonly sold as Diamox, is a prescription drug that speeds up acclimatization. Some trekkers take it as a preventive on fast itineraries, and doctors sometimes prescribe it for treating mild AMS. It has side effects, including tingling in the fingers and toes, more frequent urination and altered taste of fizzy drinks, and it is not suitable for everyone, including some people with sulfa drug allergies. Only take it on the advice of a doctor who knows your medical history. Our article on Diamox and the Mardi Himal Trek explains the options. Painkillers such as paracetamol or ibuprofen can ease a mild headache, but they do not treat the cause, so keep monitoring how you feel.
What to Do If You Feel Unwell
- Stop going higher. Do not continue to a higher sleeping altitude with symptoms of AMS.
- Rest and hydrate. Many mild cases improve with a quiet evening, fluids and a good night's sleep.
- Reassess in the morning. If you feel better, you may be able to continue. If not, stay put or descend.
- Descend if symptoms worsen. Losing even 300 to 500 meters often brings rapid relief. Never descend alone.
- Get help for severe symptoms. Breathlessness at rest, confusion or loss of coordination require immediate descent and medical attention, and possibly helicopter evacuation.
On Mardi Himal, descent is relatively simple. From High Camp you can reach Badal Danda in around an hour and Low Camp in under two, losing 400 to 600 meters. That is one reason the route is considered a good introduction to altitude. For decisions about when to stop, read when to turn back on Mardi Himal.
The Base Camp Hike and Altitude
Summit day is the highest and hardest day of the trek. You leave High Camp in the dark and climb around 900 meters to Base Camp before returning. Everyone feels breathless on this climb, and many people feel a mild headache at the top. Walk slowly, eat and drink on the way, and turn back at the Upper View Point if you feel unwell. The view from there is superb, and there is no shame in stopping. Our guide to the High Camp to Base Camp hike covers pacing for the climb.
How Acclimatization Unfolds on a 5-Day Trek
It helps to see how your body is likely to respond on a typical itinerary. On the 5-day trek from Pokhara, the first night at Pitam Deurali, around 2,100 meters, rarely causes any symptoms. You might notice slightly faster breathing on the stairs, but little else. The second night at Low Camp, close to 3,000 meters, is where some trekkers get a mild headache or a restless night. This is normal and usually clears by morning.
The third night at High Camp, at 3,580 meters, is the real test. Many people feel a dull headache in the evening, have less appetite than usual and wake several times in the night. If these symptoms are mild and ease by morning, you are acclimatizing. On the fourth day you climb to Base Camp, feel the thin air sharply, and then descend back to Low Camp, where most people sleep soundly and wake up feeling much better. By the final day, altitude is no longer a concern.
Longer itineraries add a night at Forest Camp, which spreads the climb more evenly and usually makes High Camp more comfortable.
Common Myths About Altitude Sickness
- "Fit people don't get it." Fitness has little effect on your risk. Fit trekkers sometimes suffer more because they walk faster and ignore early symptoms.
- "It only happens above 4,000 meters." Symptoms can begin around 2,500 meters, and they are common at High Camp's 3,580 meters.
- "If I got it before, I'll always get it." A previous episode is a warning sign, but a slower itinerary often makes the difference.
- "Painkillers mean I'm fine." Painkillers can mask a headache without solving the problem. If you need them repeatedly, tell your guide and do not go higher.
- "Garlic soup cures altitude sickness." It is a warming, hydrating meal and a trail tradition, but it is not a treatment. Rest, fluids and descent are what work.
Who Is More at Risk?
Altitude sickness is hard to predict. Fitness does not protect you, and very fit people sometimes suffer because they climb too fast. Age alone is not a major factor, and many older trekkers acclimatize well. The strongest predictors are a history of altitude sickness and a fast rate of ascent. If you have heart or lung conditions, high blood pressure, diabetes or are pregnant, speak to your doctor before booking. Our health articles on trekking with asthma and high blood pressure give general context.
Insurance and Evacuation
Every trekker should carry travel insurance that covers trekking to at least 4,500 meters and includes helicopter evacuation. Serious altitude illness is rare on Mardi Himal, but if it happens, a helicopter can reach High Camp from Pokhara quickly in good weather. Check the altitude limit in your policy carefully, as many standard policies stop at 3,000 meters. Our Mardi Himal travel insurance guide explains what to look for, and helicopter rescue on Mardi Himal explains how evacuation works.
How Our Guides Manage Altitude
All of our guides are licensed and trained in first aid and altitude awareness. They check in with every trekker each evening, watch for early symptoms, and adjust the pace or plan when needed. They carry a first aid kit and know the quickest descent routes from every camp. On our longer itineraries, such as the 9-day Mardi Himal Trek, the pacing is designed to give your body the best chance to adjust. On the 5-day trek from Pokhara, the extra night below High Camp does the same job in a shorter trip. Either way, you will not be pushed higher than is safe.
Quick Checklist
- Choose an itinerary with at least one night below High Camp before sleeping there
- Walk slowly on climbs and rest when you need to
- Drink three to four liters a day
- Avoid alcohol and sleeping pills at altitude
- Tell your guide about any symptoms immediately
- Never go higher with worsening symptoms
- Carry insurance that covers 4,500 m and helicopter rescue
Follow these and the altitude on Mardi Himal becomes part of the adventure rather than a threat to it.