In England, e-cigarettes may soon be prescribed on the NHS for people who want to quit smoking tobacco.
Manufacturers are invited to submit goods for approval to be prescribed by the Medicines and Healthcare Products Regulatory Agency.
E-cigarettes have been the subject of much controversy over the years about whether they should be used for this purpose.
While not completely risk-free, e-cigarettes carry a fraction of the risk of cigarettes.
In contrast to tobacco smoke, they do not produce tar or carbon monoxide.
Heating up the liquid before inhaling it may also introduce some potentially harmful chemicals, but at much lower levels than those found in cigarette smoke.
The use of an e-cigarette is often referred to as vaping since the aerosol is commonly called vapour.
Medically licensed e-cigarettes would require even more thorough safety checks than commercially sold e-cigarettes do.
More than one-fourth of smokers using e-cigarettes to quit rely on them - far more than those using nicotine-replacement therapy products such as patches or gum.
Despite being used in a number of pilot programs, they have not yet been available on prescription.
Around 3.6 million people use e-cigarettes - most of them ex-smokers.
It may improve smoking disparities across the country if e-cigarettes can be prescribed on the NHS, he said.
Prof. Peter Hajek, director of the Queen Mary University of London's tobacco dependence research unit, said the move sent a positive signal that e-cigarettes could help people quit.
Many manufacturers may not be able to afford the costs of applying for approval, making him question whether it would have the intended consequences.
Furthermore, it does not seem necessary for the NHS to pay for something smokers are happy to purchase themselves. (Buy Here)
As a whole, it seems easier to simply recommend existing products that are well regulated by consumer protection laws."