(CNN) When South Korean President Park Geun-Hye's spokesman said 364 Viagra pills bought by her office were for "altitude sickness," some online users reacted with disbelief.

"Now I get why older Koreans are so psyched to go mountain hiking every weekend," Yonsei University Professor John Delury tweeted on Wednesday.

But what if the South Korean President's office was onto something?

High-altitude mountaineers and a biochemistry expert told CNN Viagra was sometimes used by climbers to avoid altitude sickness, although its usefulness has yet to be clinically proven.

'I've carried it myself'

Veteran Australian mountaineer Andrew Lock, who has climbed all 14 of the world's 8,000 meter peaks, told CNN he first heard of climbers discuss using Viagra for pulmonary edemas about 10 years ago.

A pulmonary edema occurs when there is an accumulation of fluid in the lungs at altitude, making it hard to breath and potentially leading to death.

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"The benefit in terms of climbing is if someone is suffering altitude sickness ... that particular drug will help you dilate those blood vessels and carry that fluid away from the lungs, because if you don't get that fluid out you can actually drown in (them)," he said.

Lock said while the primary cure for a severe pulmonary edema was to descend, Viagra could help slow its development until you climb lower. "I've carried it myself for that purpose," he said.

New Zealander Guy Cotter, chief executive of mountain climbing guide company Adventure Consultants, said he knew the drug had been tested at high altitudes but didn't believe the results had proven to be negative or positive.

"We joke that the best use of Viagra on an expedition is to stop the blokes rolling out of bed at night," he said.

Medical opinion divided

According to the Institute for Altitude Medicine's website , altitude illness can refer to three different problems: acute mountain sickness, high altitude cerebral edema and high altitude pulmonary edema.

For a pulmonary edema, the institute said while Viagra is sometimes used for treatment, it hasn't been proven conclusively to help.

Speaking to CNN, biochemistry lecturer at Australia's Murdoch University, Dr Garth Maker, said from "a molecular mechanism perspective," Viagra could be potentially used to treat altitude sickness.

"It dilates the blood vessels therefore you get a drop in blood pressure. So there is certainly a basis for it (but) from what I can see the general consensus is that it's very much a 'maybe' at the moment," he said.

Maker said there were other more commonly used drugs for altitude sickness.

Pills purchased for Africa trip

South Korea's President Park Geun-Hye speaking at the presidential Blue House in Seoul on November 4, 2016.

The Viagra pills story came to light on Wednesday after a local Korean newspaper, Munhwa Ilbo, released a list of medicine purchased by the president's office between January 2014 and September 2016.

It was requested by opposition party member Kim Sang-hee. Among the items were 364 Viagra pills, 150 placenta parental injections and medicine for chronic fatigue.

"Viagra pills were purchased in preparation for altitude sickness ahead of (President) Park's visit to African nations," South Korean Presidential spokesman Jung Youn-kuk said during a daily briefing.

"None of them were used."