On a camping trip, Susanna DeForest and her friends had planned to spend the night at 11,000 feet. Then, tragedy struck. We spoke to an expert to find out what makes this illness become lethal, plus the warning signs to always pay attention to.


For adventure lovers around the country, camping in Colorado’s Rocky Mountains is a popular bucket-list item. Sadly, such a trip turned deadly last week for one Pennsylvania college student—20-year-old Susanna DeForest—who reportedly died of altitude sickness during what was supposed to be an overnight hike.

DeForest’s cause of death has not yet been publicly confirmed by the county coroner. But in a Facebook post Tuesday, her mother wrote that DeForest suffered “acute altitude sickness.” According to news reports, the Pennsylvania College of Art & Design student was hiking with three friends near Conundrum Hot Springs, which reaches an elevation of 11,222 feet, when she began to vomit.

After DeForest fell ill, the group pitched a tent and tried to make her comfortable. Two friends turned around to seek help at about 8:30 p.m., but a helicopter was only able to reach the tent early the next morning. (The hot springs are about 8.5 miles from the trailhead.) By that time, DeForest had already died.

Not much more is publicly known about DeForest’s tragic death, but what we do know is heartbreaking, especially for her friends and family who loved her. It’s also frightening for anyone who loves the mountains, as DeForest’s mother wrote that her daughter did.

We’ve all heard of altitude sickness—but how often does it turn deadly? To learn more about the risks, Health spoke with Jan Stepanek, MD, who sees patients at the Mayo Clinic’s High Altitude and Harsh Environments Medical Center in Scottsdale, Arizona. (He was not involved in DeForest's case.) Here’s what he wants everyone traveling to high elevations to know.

What is altitude sickness? “Too high, too fast”

Altitude sickness, sometimes known as mountain sickness, happens when people go “too high, too fast, and don’t allow their bodies time to adapt to the lack of ambient pressure and the lack of relative oxygen,” says Dr. Stepanek. “Our bodies are equipped to make this adjustment, but it ideally takes time.”

Mild signs of altitude sickness include headache and nausea, and for most people visiting a higher-altitude region, that’s as bad as the condition will get. But if it progresses (which it likely will if a person keeps going to higher elevations), it can lead to vomiting, disorientation, fluid in the lungs, and swelling around the brain—all of which can be deadly if not treated quickly.

Visitors—and young, fit people—are at higher risk

“The individuals who are usually struck by altitude sickness are those who fly in from the lowlands—like someone coming in from a lowland location for a ski trip with friends,” says Dr. Stepanek. “It’s very common to have a headache and not feel great for the first few days you’re there.” Luckily, he adds, those symptoms usually pass within three to four days, if you don’t go any higher once you reach your elevation.

That’s one reason young, fit people may be at risk for more complications, he says; they may continue to push themselves. “If you have these symptoms and you continue to ascend, like on a hiking trip, things are only going to get worse.”

Altitude affects everyone differently

People who live at higher elevations are less likely to get altitude sickness during a hiking or ski trip in the mountains than those who live at sea level. But even two people who live in the same place could have very different reactions to a higher altitude.

“Some individuals happen to be more sensitive to mountain sickness,” says Dr. Stepanek. That being said, some general rules of thumb apply. “If you go above 10,000 feet, you have about a 10% to 15% chance of getting mountain sickness upon arrival,” he says.

When symptoms strike, head for lower ground

“If there is one mantra everyone should know, it’s that if you have a headache, don’t take that headache higher,” says Dr. Stepanek. He also encourages patients planning a mountain visit to be on the lookout for loss of balance, a sign that the condition may be worsening. Loss of balance “can help distinguish between annoying mild mountain sickness and something that could be the beginning of a brain edema, or swelling in the brain,” he says.

Medications are available to treat severe altitude sickness, but “the best treatment for any altitude-caused condition is to descend, descend, descend,” says Dr. Stepanek. “Going down 500 meters, about 1,500 feet, doesn’t sound like much—but that increase in pressure and improvement in oxygen delivery can make a world of difference.”

Planning a trip? Take time to acclimate—and check with your doctor

Anyone planning a rigorous trip above 10,000 feet should consider taking a few days to adapt to the hike’s starting elevation before heading even higher, says Dr. Stepanek. (According to Colorado newspaper the Post Independent, DeForest and her friends did take this precaution, spending two days in Colorado before setting out on the trail.) Drinking plenty of water and monitoring your alcohol intake is also important for feeling good while at elevation, although neither will protect against actual altitude sickness.

Checking in with a doctor before you go is also a good idea, says Dr. Stepanek. Not only can a physician evaluate whether you’re physically fit enough to make such a trip, but he or she may also prescribe medicine that can help the body adapt faster to high elevations.

“If you have been at sea level for the last 90 days, it’s probably wise to talk to your physician, or a physician who’s familiar with altitude medicine,” says Dr. Stepanek. “You want to do everything you can to avoid these annoying, and potentially very dangerous, symptoms from occurring.”