In a new publication directed at travelers, the American Medical Association (AMA) warned that going quickly from low to high altitude can cause headache, fatigue and nausea. Acute mountain sickness affects more than one in four people who travel above 3,500 meters, and more than half of those who travel above 6,000 meters. Many popular ski resorts in the Rocky Mountains and the Alps, for example, are well above those elevations. Dr. Jill Jin of Northwestern University in Evanston, Illinois, who wrote the paper, said: “With winter and the holiday season approaching, it’s time for travelers to be careful as they visit high altitudes,” She also told Reuters Health: “It’s important to talk about the signs, symptoms and treatment.” Headache, fatigue, poor appetite, nausea, vomiting, light-headedness and sleep disturbances that develop six to 12 hours after ascent all can be symptoms of acute mountain sickness, the article warns. The problems usually improve in one or two days if the traveler does not go higher. In less than 1% of cases, symptoms can grow worse and turn into high-altitude cerebral edema. Jin said: “Everyone is susceptible, even if you’re young. Everyone can experience it, regardless of gender and age.” Acute mountain sickness is easy to diagnose in healthy adults, but can be harder to spot in children and those with health problems. Treatment usually includes rest, hydration and pain medicine for headaches. Some patients need supplemental oxygen and other medicines. People with persistent severe symptoms should go back down to a lower altitude. The paper says a gradual ascent of 400 meters per day can help prevent acute mountain sickness. Travelers can also try regular exposure to altitude, as well as hydrating with water.