Experts claim negativity surrounding the e-cigarettes is "seriously disproportionate" to the available research - with one health worker saying a switch to e-cigarettes is actually almost as good as giving up smoking completely.
The comments come on the back of calls from the World Health Organisation (WHO) to ban the use of e-cigarettes, formally known as Electronic Nicotine Delivery Systems (ENDS), in enclosed public places amid claims they carry a risk.
The anti-smoking charity ASH has said it does not favour a ban.
The WHO report states: "The fact ENDS exhaled aerosol contains on average lower levels of toxicants than the emissions from combusted tobacco does not mean these levels are acceptable to involuntarily exposed bystanders."
But addiction specialist Professor Neil McKeganey, director of the Centre for Drug Misuse Research in Glasgow, claims the WHO recommendations are a "knee-jerk reaction". He said: "E-cigarettes are probably the most beneficial way of reducing the harm associated with smoking for those who are determined to carry on consuming nicotine.
"The fears that are now being generated, including by senior health professionals, are disproportionate and could seriously undermine attempts by people to use e-cigarettes as an opportunity to reduce their smoking or stop. This would be hugely regrettable, especially as these fears are theoretical.
"WHO have rather prematurely advised the ban of e-cigarettes indoors when the evidence of passive consumption is nowhere near the level of having been shown demonstrably. It's an excessive regulation."
McKeganey said there is "no question" that e-cigarettes are safer than tobacco products, adding that some of the claims are "completely eccentric" and "fantastical".
"I think it's to do with views on smoking by public-health leaders," he said. "Smoking is such a major factor in ill-health and premature death and so much effort has been put into getting people to stop smoking, and because it's nicotine in these cigarettes, many people have assumed that they're just as bad.
"They've not really given e-cigarettes a fair hearing and have been far too ready to try to limit their use."
The first e-cigarettes went on sale in the UK in 2005 and are now used by at least two million people. Some use them to stop smoking, while others use them as a safer alternative.
According to the WHO, 30 countries have disallowed their use in indoor public places, while 39 have banned their advertising and sponsorship.
John Britton, director of the UK Centre for Tobacco Control Studies, agreed that there is a lot of negativity surrounding the products when, in fact, they are substantially less harmful than regular cigarettes.
He said: "E-cigarettes are a very useful development in nicotine addiction. They get smokers to stop smoking tobacco, while still providing the nicotine they're addicted to.
"Obviously, the best thing for smokers is to stop completely, but the next best option is to switch to some other form of nicotine. Over the long term, they're almost as good as giving up."
The Scottish Government is considering the WHO proposals, but has set out plans to ban sales of e-cigarettes to under-18s - another WHO recommendation.
A European Union directive on e-cigarettes issued earlier this year also made it clear that all products should be properly regulated by 2016.
E-cigarettes are regulated as consumer products but will be controlled by either the Medicines and Healthcare Products Regulatory Agency (MHRA) or another Government body within the next two years - a move which has been welcomed by healthcare professionals.
McKeganey said: "There clearly needs to be tighter regulations on their production and sale - either through a medicines body or some other Government body."
But he added the Government should instruct further research before deciding how best to regulate the devices - a suggestion rebuffed by the Scottish Government which says it has no plans to do so.
Britton welcomed tighter regulation, raising concerns over "irresponsible manufacturers" which do not provide data on emissions. "The sooner the products are regulated so that consumers are provided with this information, the better," he said.
The Electronic Cigarette Industry Trade Association (ECITA) added that while it welcomed regulation, it has concerns over how it would be done.
Tom Pruen, chief scientific officer for ECITA, said: "We have always been pro-regulation but the problem is e-cigarettes don't fall within the medicines family or the tobacco family - they need to be regulated as e-cigarettes and nothing else.
"There needs to be a regulatory framework that looks at the products for what they are, examines the formulation of the liquid and details what you can and can't put in them. That's what we've been advocating."
Pruen added that e-cigarettes are 99% safer than conventional cigarettes. He said: "All the evidence suggests that emissions from e-cigarettes are nowhere near as dangerous as cigarette smoke. Banning them indoors flies in the face of the evidence. Being able to use them indoors is a big incentive for people to move away from tobacco, so there's a risk this will put people off trying e-cigarettes."
The anti-smoking charity, ASH Scotland, said it is neither for nor against e-cigarettes, but does not favour a ban.
Charity chief executive Sheila Duffy said: "A legislative ban on using e-cigarettes in enclosed public spaces would require clear scientific consensus that harm from 'second-hand' e-cigarette emissions is likely. This is not the situation to date, so we don't consider a blanket ban is appropriate."
A Scottish Government spokeswoman said: "The Scottish Government agrees that electronic cigarettes need appropriate regulation. While we accept that the devices may potentially help people smoke fewer cigarettes, or even stop altogether, there is concern that they could also re-normalise smoking.
"The Scottish Government has said that we will introduce a restriction on the age at which an e-cigarette can be purchased to protect young people.
"We are exploring what more can be done in Scotland now that the European Tobacco Products Directive has set out its measures for regulation and we will consider all available options."