Hiking Injuries and Trail Safety: Sprains, Knees, Heat, Altitude and Getting Help

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Two miles from the trailhead, someone steps on a rolling stone, the ankle folds, and the whole group stops. Or it’s the long way down from a summit, knees aching with every step as the sky behind the ridge goes dark. Hiking is one of the gentlest ways to stay fit for life, from a family nature walk to a week on the Appalachian Trail, but the trail is far from help: a sprain that would be a nuisance in a gym can mean a long walk out, or a rescue. This page covers the hiking injuries and illnesses that show up most, how to lower the risk, and when to stop and get help.

General information, not medical advice. If you’re hurt, see a sports medicine doctor, physical therapist (PT) or athletic trainer; in an emergency call 911 or use your satellite SOS. For the bigger picture, start at our hiking hub.

How often hikers get hurt

Most hikes end with nothing worse than tired legs. On long trips, though, aches add up. In a survey of 1,295 long-distance hikers on the Appalachian Trail (2018–2019), 61% reported a musculoskeletal complaint, and 11% had to stop their hike because of one. On 12-day treks at Philmont Scout Ranch, 7% of 1,206 Scouts and leaders reported an injury, mostly minor. And in Yosemite, a 10-year review of 1,088 backcountry medical calls found that 46% happened while hiking on a trail and that extremity pain was the main complaint in 53%; 79% of incidents happened on clear days, and most patients called themselves experienced.

Ankle sprains

Roots, rocks and wet slabs make rolled ankles the classic trail injury. The American Academy of Orthopaedic Surgeons (AAOS) describes a sprain as ligaments stretched past their limit: pain, swelling, bruising and an ankle that feels like it “gives out”. The National Athletic Trainers’ Association (NATA) says the most consistent risk factor is a previous sprain, and recommends a balance and neuromuscular program of at least three months, plus a brace or tape for athletes who have sprained before. On the trail, check whether you can bear weight and decide early whether to turn back. AAOS lists rest, ice, compression and elevation as first care; if you can’t walk on it, or it may be broken, it needs a doctor. Our ankle brace guide compares braces like the ASO EVO.

Knee pain on the way down

Going up burns the lungs; coming down punishes the knees and thighs. Downhill walking makes the thigh muscles brake while they lengthen, which causes temporary muscle damage and sore legs. In a study of 37 hikers on Snowdon, the highest peak in England and Wales, the group using trekking poles felt less effort on the climb, had less muscle soreness 24 and 48 hours later and kept more of their leg strength than the group without poles. A 2020 review in Wilderness & Environmental Medicine concluded that poles reduce the load on the legs (at a small extra cost to the heart and lungs), and may help balance with a heavy pack. In the Appalachian Trail survey, poles were also associated with fewer complaints. Shorter steps on steep descents and leg strength built beforehand help; see hiking training. Knee pain that keeps coming back, swelling, locking or giving way is a reason to see a sports medicine doctor or PT.

Blisters

A 2017 systematic review of blister prevention in outdoor pursuits found little strong evidence for any one sock or antiperspirant, but moderate evidence for paper tape: in a trial of 128 multistage ultramarathon runners, paper tape on blister-prone spots cut blisters by 40%. Many hikers tape known hot spots before starting, wear broken-in footwear and moisture-wicking socks, and stop at the first hot spot. The American Academy of Dermatology (AAD) advises covering a blister loosely and not popping it; if one must be drained, keep the skin “roof”, wash with soap and water and cover. Redness that spreads, pus, warmth or fever means infection: see a doctor.

Falls

Falls cause many serious hiking injuries, from broken wrists to head injuries. A study of 405 hikers hurt in falls in Tyrol, Austria, found they were older than the average hiker (mean age 56) and that 70% had impaired vision. The National Park Service (NPS) advises staying on marked trails and watching your footing near water and cliffs. After a hit to the head, follow the CDC’s HEADS UP rule: stop for the day, and get emergency care for danger signs such as a worsening headache, repeated vomiting, slurred speech, one pupil larger than the other, unusual drowsiness or confusion.

Heat illness and dehydration

Grand Canyon National Park says most of the people who need emergency help there for heat illness are hiking between 10 a.m. and 4 p.m., and that hikers can lose one to two quarts (liters) of water an hour in the heat. Its rangers list the signs of heat exhaustion (fatigue, nausea, vomiting, cool and moist skin, headache, cramps: rest in shade and drink water with electrolytes) and of heat stroke (a medical emergency: confusion, high body temperature, a flushed face; cool the person immediately and call for help). NATA’s rule for exertional heat stroke is “cool first, transport second”. The park also warns about hyponatremia: drinking a lot of plain water while losing salt in sweat, which looks like heat exhaustion. Eat salty snacks along with water. More on how much to drink is on Hike Day.

Hypothermia

It doesn’t take snow. The CDC notes hypothermia can happen even above 40°F when someone is chilled by rain, sweat or cold water, which is exactly the wet, windy afternoon on an exposed ridge. Warning signs in adults: shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness. Get them out of the wind and into dry layers and shelter, with warm, non-alcoholic drinks if alert; a body temperature below 95°F is an emergency. This is why extra clothing and emergency shelter are on the NPS list of Ten Essentials.

Altitude sickness

The CDC’s Yellow Book says any unacclimatized traveler who sleeps at 8,000 feet (2,450 m) or higher, and sometimes lower, is at risk; about 25% of visitors sleeping above that height in Colorado get acute mountain sickness (AMS). The main symptom is a headache, with loss of appetite, dizziness, fatigue, nausea or vomiting, usually 2 to 12 hours after arriving higher. Two rare but dangerous forms need immediate descent and medical care: HACE (brain swelling: confusion, clumsiness and drowsiness like being drunk) and HAPE (fluid in the lungs: breathlessness even at rest, cough). The CDC’s guidance above 10,000 feet (3,000 m): raise your sleeping altitude by no more than about 1,650 feet (500 m) a night, add an extra night for every 3,300 feet (1,000 m) gained, and descend if symptoms get worse despite rest. Ask your doctor about preventive medicine before a high trip.

Lightning

The National Weather Service is blunt: no place outside is safe in a thunderstorm. In the mountains storms usually build in the early afternoon, so “plan to hike early in the day and be down the mountain by noon.” If you’re caught out, get off peaks and ridges, avoid isolated tall trees, open fields and water, and spread out a group so one strike can’t hurt everyone. A tent offers no protection.

Wildlife, ticks and snakes

• Bears (NPS): hike in groups and make noise, carry bear spray where bears live, never let a bear get your food, and do not run. If a grizzly attacks, leave your pack on and play dead; if a black bear attacks, don’t play dead: get to a safe place or fight back.
• Ticks (CDC): use an EPA-registered repellent (DEET, picaridin and others), treat clothing with 0.5% permethrin, check your whole body after the hike and shower within two hours.
• Snakes (CDC): watch where you step and put your hands, especially at dawn, dusk and in warm weather. If bitten, keep calm, wash and cover the bite, take off rings and get emergency care. Don’t cut the wound, suck out venom, use a tourniquet or ice.

Your heart on the mountain

Research from the Alps finds sudden cardiac death is the leading non-traumatic cause of death in mountain hiking; a previous heart attack, diabetes and high cholesterol were the main risk factors, and regular mountain activity was protective. With heart risk factors, see your doctor before a big hike or a trip to altitude.

Gear many hikers carry for this

None of these prevent injuries by themselves, but they’re common in a good first-aid kit: Compeed blister pads, 3M Micropore paper tape, a brace if you’ve sprained before (ask your PT) and, beyond cell service, a PLB like the ACR ResQLink 400.

When to get help, and how search and rescue works

• Call 911 or press SOS now: concussion danger signs, signs of heat stroke, HACE or HAPE, a hypothermic person who is confused or has stopped shivering, a snakebite, a possible broken bone or someone who can’t walk out.
• Turn back: a sprain you can walk on, an AMS headache that isn’t improving, a hot spot turning into a blister, or a storm building.
• See a professional at home: pain or swelling lasting more than a few days, knee pain on every descent, or any blister that looks infected.

In US national parks, 2003–2006 saw 12,337 search and rescue (SAR) operations; day hiking caused the most, mostly through errors in judgment, fatigue, and too little equipment, clothing or experience. Most people were found within 24 hours. Three things help rescuers: leave a trip plan with someone at home (where you’re going, who’s with you and when you’ll be back, as the NPS advises), stay put once you know you’re lost, and carry a way to call for help where phones don’t work. A personal locator beacon sends your position on 406 MHz to search and rescue with no subscription; in the US it must be registered with NOAA (free, renewed every two years). Satellite messengers add two-way texting; compare them on our hiking wearables page. Recovery after a hard trip is on hiking recovery.

Hiking injuries: FAQs

What is the most common hiking injury?

Lower-body problems lead: ankle sprains, knee pain and blisters, with overuse aches on long trips. In a large Appalachian Trail survey, 61% of long-distance hikers reported a musculoskeletal complaint; in Yosemite’s backcountry, extremity pain was the main complaint in 53% of medical calls.

Do trekking poles really help your knees?

Research says they lower the load on the legs. In a study on Snowdon, hikers with poles had less soreness and kept more strength in the days after the hike, and a 2020 review found poles reduce lower-body forces. They cost a little extra effort for the heart and lungs.

At what altitude does altitude sickness start?

The CDC says anyone unacclimatized who sleeps at 8,000 feet (2,450 m) or higher is at risk, and sometimes lower. About a quarter of visitors sleeping above that in Colorado get acute mountain sickness. Worsening symptoms mean go down.

Should I pop a blister on the trail?

The American Academy of Dermatology says try not to; cover it loosely. If it’s large and painful and must be drained, keep the top skin in place, clean it with soap and water and cover it. Watch for signs of infection.

What should I do if I get lost?

Stop and stay where you are, especially if someone has your trip plan. Call for help by phone, satellite messenger or PLB, and stay warm and visible. Most people searched for in national parks are found within 24 hours.