The anti-inflammatory drug ibuprofen can reduce acute altitude sickness suffered by a quarter of the millions of Americans who travel to the mountains to ski or hike, according to a clinical study published Tuesday.
Lead researcher, Grant Lipman of Stanford University, described altitude sickness as being like "a really nasty hangover".
The symptoms include headache, fatigue, dizziness, nausea, vomiting and poor appetite.
In the worst cases, altitude sickness can cause cerebral oedema, an often fatal brain swelling.
Ibuprofen, an active ingredient in over-the-counter painkillers like Advil, reduced altitude sickness symptoms by 26 percent in a study of 58 men and 28 women, Lipman and his research team reported.
The study was published in the online version of the Annals of Emergency Medicine.
The study participants travelled to an area of the White Mountains, California, where they spent the night at 1250 metres.
At 8 am, they were given either 600 milligrams of ibuprofen or a placebo before heading up a mountain to an area at 3570 metres. There, they were given a second dose at 2 pm.
They then hiked to 3830 metres, where they received a third dose at 8 pm before spending the night on the mountain.
Of the 44 participants who received ibuprofen, 19 (43 per cent), suffered symptoms of altitude sickness, whereas 29 of the 42 participants who received placebos had symptoms, according to the study.
In other words, ibuprofen reduced the incidence of the illness by 26 per cent.
Among study participants who suffered altitude sickness, symptoms were less severe in the persons who took ibuprofen, the researchers report.
Reducing the swelling
At high altitudes, decreased atmospheric pressure reduces oxygen molecules in the air, making it harder for people to breathe.
Some researchers believe altitude sickness occurs because a lack of oxygen to the brain causes it to swell with fluids. Ibuprofen appears to reduce the swelling, according to the Stanford researchers.
Other altitude sickness drugs are available, such as acetazolamide and dexamethasone, but they can have more undesirable side effects than ibuprofen, according to the researchers.
Ibuprofen's milder side effects can include the possibility of gastrointestinal and kidney problems in people who are dehydrated, the researchers write.
Professor Ric Day, of the School of Pharmacology at the University of New South Wales says, the effect observed in the study is small, despite the dosage used being higher than the recommended daily dosage - 1800 milligrams compared to 1200 milligrams.
But he adds "their argument is that it's a pretty well-known, reasonably tolerated drug ... and if it's of benefit why not use it."
Day recommends that anyone contemplating using ibuprofen to avoid altitude sickness follows the instructions on the packet.
"If they are reasonably well, read the instructions, don't have any pre-existing problems and as much as you can keep yourself hydrated, it would generally not be a bad thing to do," he says.
"But if you've had an ulcer, hypertension or a kidney disorder you ought to talk to your doctor."
Day is also a researcher at St Vincent's Hospital in Sydney and an advisory council member for the pharmaceutical company Reckitt Benckiser, which manufactures a brand of ibuprofen.