How to prevent blisters, sunburn, Khumbu cough, and other environmental hazards in the Everest Region?

Environmental hazards are the most preventable risks on the Everest Base Camp trek, because nearly every one is answered by something you pack or a habit you keep. The ones most trekkers meet are the Khumbu cough, blisters and sunburn. The rare ones that matter most are frostbite, carbon monoxide and a dog bite.

Which environmental hazards are you most likely to face on the Everest Base Camp trek?#

Hazard	Where it peaks	How common	What prevents it
Khumbu cough	Dingboche (4,360 m) and above	22 to 42% of trekkers in Everest-region surveys	Buff over nose and mouth, easy pace, warm fluids
Blisters	The first trail days, and the 15 to 19 km descents on the walk out	More than 70% of medical visits in multistage foot races	Broken-in boots, liner socks, tape on known hot spots
Knee pain	The walk out: three long, mostly downhill days from Gorakshep to Lukla	No published trekking figure	Poles on every descent, short strides, leg training at home
Sunburn and snow blindness	Lobuche (4,940 m) to Kala Patthar (5,644 m), worst on fresh snow	No trekking figure. UV at Base Camp is about half again sea level	SPF 30 to 50 reapplied at midday, category 3 or 4 wraparound glasses
Hypothermia and frostbite	Nights at Lobuche and Gorakshep (5,164 m), and wind on exposed ground	No published trekking figure	Layers, no cotton, staying dry, out of the wind
Carbon monoxide	Closed bedrooms with a heater or stove	No published trekking figure	No flame in a sealed sleeping room
Dog bites	Villages along the route	1.2 possible rabies exposures per 1,000 trekkers a year	Do not touch dogs; wash any bite for 15 minutes

Most of the last column is a packing list, and the full list, with quantities, is in our Everest Base Camp trek packing list. The sections below take each hazard in turn.

What causes the Khumbu cough, and what actually helps?#

Nobody knows exactly what causes the Khumbu cough, but a buff over your nose and mouth, nose breathing, an easy pace and warm fluids are still the best defense. It is very common: in one survey of 283 trekkers in the Everest region, 42% had some form of cough.

The usual explanation is cold, dry air irritating the airways. It is incomplete. In a hypobaric chamber study, subjects on a simulated ascent of Everest coughed more as the simulated altitude rose, even though the chamber was kept warm and humid (Mason and Barry, Altitude-related cough). Altitude itself seems to make the airways more sensitive: in climbers at Base Camp, the threshold for triggering a cough fell after six or more days at altitude.

Warming and humidifying the air you breathe is still cheap and harmless. Keep the buff on at night too, and sit away from the stove in smoky dining rooms, where burning dung and wood add their own irritation. Lozenges and warm drinks ease the cough, and hot drinks are on every lodge menu (more on food and drinks on the EBC trek). A severe cough can crack a rib, which has been reported in climbers at extreme altitude.

A cough is not always the Khumbu cough, though. Breathlessness out of proportion to your effort, a sudden drop in how far you can walk, breathlessness at rest, or pink or bloody sputum are signs of high-altitude pulmonary edema (HAPE). Unlike the Khumbu cough, HAPE can be fatal.

How strong is the sun at Everest Base Camp, and how do you avoid sunburn and snow blindness?#

UV rises about 10% for every 1,000 m you climb, so at Everest Base Camp (5,364 m) you get roughly half again as much UV as at sea level, and fresh snow can almost double it.

Use a broad-spectrum sunscreen of SPF 30 to 50 at least fifteen minutes before exposure. Apply it before you leave the lodge, again at midday before lunch, and after heavy sweating, because how much you use and how often matters more than the number on the bottle. Carry an SPF lip balm and use it frequently.

Snow blindness is a sunburn of the cornea. It does not hurt while it happens. Pain starts 6 to 12 hours later, often at night, with gritty, streaming eyes that will not stay open. The cornea usually heals in 24 to 72 hours with rest in a dark room and pain relief. Prevention is wraparound sunglasses, category 3 or 4, worn religiously when you are outdoors even on overcast days. This is because UV penetrates cloud cover. Don’t forget to use a strap, and carry a spare pair. Glasses lost at 5,000 m cannot be replaced.

How do you prevent blisters and chafing on the Everest Base Camp trek?#

Break in your boots at home, and tape hot spots before you start walking. While shopping for shirts, avoid those with shoulder seams. Seamless quick-dry boxer briefs earn their place if you are prone to chafing in the thighs and where the light seldom shines.

Most blisters on this trail are fit problems, and fit is solved at home, not on the trail. On a HoneyGuide Everest Base Camp trek, the full gear list arrives two months before departure, and your kit is checked against it in Kathmandu, so any gap is fixed before the flight to Lukla.

The evidence on taping is mixed. In a 2016 randomized trial of 128 multistage ultramarathon runners, paper tape on blister-prone spots reduced blisters (Lipman, Clinical Journal of Sport Medicine). An earlier trial by the same group found no benefit. Tape is cheap and weighs nothing, so the balance favors using it. Wear thin liner socks under merino, and stop at the first hot spot to cover it.

Chafing follows the same logic. Wear seamless synthetic or merino underwear, avoid cotton, and put a barrier cream on your inner thighs and under your pack straps before it starts.

How do you prevent knee pain on the Everest Base Camp trek?#

Use trekking poles on every descent, shorten your stride on steep steps, and train your legs at home before you go.

Descents are where knees suffer. The walk out from Gorakshep to Lukla covers about 15, 19 and 18 km on three consecutive days, most of it downhill on stone steps. In a laboratory study of downhill walking on a 25-degree slope, poles cut knee joint forces by 12 to 25% (Schwameder, Journal of Sports Sciences, 1999). Shorten your stride on steep steps, and do not rush the easy stretches. A practical rule is to descend only slightly faster than you climbed.

Training at home counts as much as poles. One group of trekkers in their late 60s and early 70s, all with knee problems, prepared by walking at least 8 km a day on HoneyGuide’s advice, then walked to Base Camp at their own pace (Ishita, TripAdvisor, May 2023).

How cold does it get, and how do you avoid hypothermia and frostbite?#

Stay dry, layer your clothing, use waterproof boots, and check in at lodges at least an hour before sunset. Nights above Dingboche fall below freezing for much of the trekking year, and at the Pyramid research station near Lobuche (5,050 m), the average temperature in February, the coldest month, is about -9°C. The absolute minimum can go as low as -20°C.

Wet clothing and wind take heat away fast, so focus on staying dry first: layer, and change damp clothing quickly. Avoid cotton, which holds sweat against your skin. Keep your shell and warm layer in your daypack, because afternoons turn cold quickly as the wind picks up and clouds roll in. On HoneyGuide treks, the guide gets a weather review from Kathmandu every evening so the decision to wait out a cold, windy day rests on a forecast rather than a glance at the sky.

Hypothermia shows first as shivering, then fumbling hands, slurred speech and confusion. Shivering is the warning. Get into shelter, change out of anything wet, add layers, and drink something warm.

Frostbite starts with numbness in the toes, fingers, nose, cheeks or ears, and skin that turns white or grayish and feels firm or waxy. If a part freezes, do not rub it, and do not thaw it if it could freeze again. Refreezing does more damage than staying frozen. Rewarm only when the part can be kept warm, in water held at 37 to 39°C (98.6 to 102.2°F), never by a stove or fire (Wilderness Medical Society, 2024). Frostbite needs immediate medical attention.

How do you stay safe around yaks, dogs and other animals?#

Step to the mountain side when pack animals like mules or yaks pass, and do not touch dogs, however friendly, because any bite or scratch in Nepal means a course of rabies vaccine. At the CIWEC travel clinic in Kathmandu, possible rabies exposures among trekkers ran at 1.2 per 1,000 people a year in a 1996 to 1998 study (Pandey, Journal of Travel Medicine). Most dog bites on foreign visitors land on the legs.

If you are bitten or scratched, wash the wound with soap and running water for at least 15 minutes, then get to a clinic for post-exposure vaccine as soon as you can (World Health Organization). In Kathmandu, the CIWEC clinic stocks both rabies vaccine and rabies immune globulin. Rabies vaccine before the trip simplifies that treatment but does not replace it.

Sources#

Mason NP. Altitude-related cough. Cough 2013;9:23. The prevalence figures and the hypobaric chamber evidence behind section 2.
World Health Organization. Radiation: ultraviolet (UV) radiation. How UV rises with altitude and how snow reflects it.
Backer HD, Freer L. Heat and Cold Illness in Travelers. CDC Yellow Book 2026. Cold prevention, co-written by Luanne Freer of Everest ER, the clinic at Base Camp.
McIntosh SE, Freer L, Grissom CK, et al. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2024 Update. Wilderness & Environmental Medicine. The field rewarming rules for frostbite.
Pandey P, et al. Risk of possible exposure to rabies among tourists and foreign residents in Nepal. Journal of Travel Medicine 2002;9(3):127.