Dedicated mountain climbers will scale mountains regardless of the risks. Now, their loved ones may sleep a little easier, knowing that one of those risks could be reduced by simply taking a common over-the-counter drug. A report on the subject was published in the journal Wilderness and Environmental Medicine.

Altitude sickness, also known as acute mountain sickness (AMS), develops when somebody climbs too high too quickly. Severe AMS can kill you, but the mild version, with its hangover-like headache, nausea, dizziness, and fatigue, is no fun either.

For a long time, doctors’ go-to option for altitude sickness was a drug called acetazolamide. But many people are allergic to acetazolamide, and those that aren’t still don’t enjoy the tingling and burning sensations it can produce in their hands and feet. The alternative to this drug is ibuprofen (a.k.a. Advil or Motrin), which works well but comes with its own suite of nasty side effects.

Researchers wondered if there wasn’t a better option hiding in plain sight. Acetaminophen (a.k.a. Tylenol) is already used to treat many of the same issues as ibuprofen without the gastrointestinal ugliness. Could it also match ibuprofen’s AMS-stopping skills?

To find out, the scientists recruited 332 climbers ascending Mount Everest. They told each person to take either ibuprofen or acetaminophen three times per day as they journeyed upward. When they reached the settlement of Lobuche—16,210 feet above sea level—the climbers were given medical examinations to see if they’d developed AMS.

Unfortunately, a few of them had. Out of 225 climbers who completed the study, 43 showed signs of AMS. Out of those, 18 had taken ibuprofen and 25 were on acetaminophen. In other words, for the majority of mountaineers, both drugs had worked.

The authors acknowledge that their study was small and that more research is needed.

"The best prevention of altitude illness is a slow ascent," they write. "However, proper acclimatization might be ignored or deemed impractical by mountain climbers, hikers, local pilgrims, rescue teams, or military operations."

For these people, the authors note, acetaminophen might be a good choice.