Five people have died due to a mystery lung disease that doctors think may be caused by vaping.
The Centres for Disease Control and Prevention has said the number of possible cases of severe respiratory illness from people who vape or use e-cigarettes now stands at around 450 across 33 states in the US, NPR reports.
A large percentage of those who have become ill reported using cannabis-derived vaping products with THC - while a much smaller group said they had only vaped nicotine.
In response to the recent spate of illnesses, the CDC is now urging people to pack in vaping until they get to the bottom of the problem.
Dr. Dana Meaney-Delman, from CDC, said: "While this investigation is ongoing, people should consider not using e-cigarette products.
"People who do use e-cigarette products should monitor themselves for symptoms, for example, cough, shortness of breath, chest pain, nausea and vomiting - and promptly seek medical attention for any health concerns."
As yet, no infectious causes have been identified, but the CDC has said the 'lung illnesses are likely associated with a chemical exposure'.
On Thursday, New York health officials said that tests discovered vitamin E acetate in a number of vaping cartridges containing cannabis that had been handed in by people who had become ill.
The officials said this now 'a key focus' of the investigation.
The Food and Drug Administration is now analysing samples for a wide range of substances and is warning people to 'think twice' before buying any vaping cartridges from any unregulated sources.
Mutch Zeller, director of the FDA's Centre for Tobacco Products, said: "With these increasing reports.
"If you're thinking of purchasing one of these products off the street, out of the back of a car, out of a trunk, in an alley - or if you are then going to go home and make modifications to the product yourself using something that you purchased from some third party or got from a friend - think twice."
Featured Image Credit: PA
Topics: US News