Some young drinkers in the US are fast catching up on a "highly dangerous" trend which involves inhaling liquor, instead of drinking it, to avoid excess calories.

Inhaling liquor involves either pouring it over dry ice or 'freebasing' it and sucking up the vapours. However, doctors have warned the practice is "incredibly risky", the New York Daily News reported.

"Inhaling alcohol is an insidious trend, particularly among college students who may be looking for more extreme ways to get high, said Dr Harris Stratyner, regional clinical vice president of Caron Treatment Centers in New York.

He has also seen it gain popularity among college-age men and women who may restrict calories before a night of partying popularly known as "drunkorexia."

Whether it's "smoked" using dry ice or inhaled as a vapour, consuming alcohol in this way is "unbelievably dangerous," Stratyner said.

"When you inhale alcohol, it goes directly into the lungs and circumnavigates the liver," he told the Daily News.

"The liver is what metabolises alcohol, but when you inhale it, it goes directly from the lungs to the brain," Stratyner said.

The lungs and mucous membranes are extremely sensitive to alcohol, Stratyner said, and inhaling alcoholic vapour may dry out the nasal passages and mouth, leaving users more vulnerable to infection.

Additionally, inhaling alcohol can lead to deadly alcohol poisoning more readily than sipping your drink.

"One of the things that prevents alcohol poisoning is that you usually vomit," Stratyner said.

"When you circumvent the stomach and go straight to the lungs, you don't have that ability," he said.

Stratyner first saw the trend pop up in 2004 and said it has escalated in the past year and a half.

"This is a stupid, highly dangerous thing to do. The fact that youngsters in particular can purchase the equipment for a relatively cheap price... this has to be made illegal," he said.