The use of electronic cigarettes will be banned in Scottish hospitals in Scotland in the coming weeks.
New laws mean NHS boards must ensure their premises are smoke-free by April.
The Scottish government said it is the responsibility of the individual health boards to prevent the use of e-cigarettes.
A survey by BBC Scotland found that only one health board will not fully ban the use of the devices.
NHS Lothian will allow their use in designated areas away from entrances to the hospital.
Other health boards raised concerns about how safe unregulated e-cigarettes are.
Julie White, chief operating officer NHS Dumfries and Galloway, said: “Our directors of public health across the health boards in Scotland have issued some advice to us which basically states that until we have more evidence available to us around their use and their impact, they should be treated like any other nicotine product and they should not be used in the grounds.”
Ms White added the policy may be reviewed if the regulatory stance changes.
An NHS Greater Glasgow and Clyde spokesperson said e-cigarettes will not be permitted as part of its smoke-free policy.
They said: “These products are currently not regulated and there are concerns over potential safety issues with the products.
“In addition e-cigarettes mimic the habit and look of smoking and therefore provide negative role modelling for young people.”
The move has been criticised by ASH Scotland, an anti-smoking charity.
Chief executive Sheila Duffy (pictured) said: “There is a clear case for hospital grounds to be free from tobacco use, which is always dangerous.
“However, e-cigarette policies should not be so restrictive that they discourage smokers from trying an alternative that might help them to move away from tobacco.”
Ms Duffy added: “Hospitals might also choose to draw a distinction between devices which look like cigarettes and some new vaping devices, which look nothing like a traditional tobacco cigarette and so don’t lead to confusion with smoking.”
The move was also criticised by Simon Clark, director of smokers’ organisation Forest.
He said: “Many smokers use e-cigs to cut down or quit tobacco so it seems perverse to prohibit their use.
“Banning them is counter-productive because if both products are prohibited there will be no incentive to switch to e-cigarettes.
“Smokers will simply carry on smoking, ban or no ban.”
The government’s tobacco control strategy provides all health boards must make their hospitals smoke free before April.
Many have already complied with the strategy and others, including NHS Tayside and NHS Lothian are removing smoking shelters.
A spokesman for the government said: “It is a matter for boards to decide how they implement and enforce their smoke-free policies, this includes whether they chose to incorporate a ban on e-cigarettes.
“No specific resources have been allocated.
“However, the Scottish government allocates around £11m a year to NHS Boards for smoking-related services.”