"You can't immediately do a five-mile hike as if you were at sea level." —Doreen Loofburrow, AAA Travel
Know the signs
Altitude sickness affects up to 20 percent of people traveling above 8,000 feet. The air low pressure makes it hard to get enough oxygen, no matter your age or fitness level. As you gain elevation, watch for headache, fatigue, nausea, and loss of appetite.
Take it slow
On a longer trip, plan a gradual ascent schedule that will help you acclimate. Block time for rest, and don't do anything too demanding until you've adjusted. "Your itinerary may look too leisurely on paper, but when you're there, you'll realize it was the right thing to do," says Doreen Loofburrow from AAA Travel.
If you feel unwell, stop ascending and rest. If your symptoms worsen, descend and seek treatment. On the train to Jungfraujoch, onboard medics can check vitals. If you're having trouble, you can get off and board the next train heading down. In other locations, notes Loofburrow, "Some hotels have oxygen on hand, and it helps."
In the thin air, it's natural to breathe faster and deeper, which can cause dehydration. Drink plenty of water on the trip—Loofburrow recommends packing a collapsible bottle with a filter—and avoid alcohol.
This article was first published in Summer 2018. Some facts my have aged gracelessly. Please call ahead to verify information.