Doctors should tell patients that e-cigarettes are less harmful than smoking but not without risk, according to new national guidance.
The National Institute for Health and Care Excellence (Nice) said evidence on the long-term health impact of vaping is not yet fully understood.
However, the body said this should not discourage smokers from switching to e-cigarettes, which it considers are “likely” to cause less damage.
The new Nice guideline on helping people quit smoking, developed with Public Health England and published on Wednesday, reinforces current best practice for health professionals.
It states that patients using or interested in using e-cigarettes to stop smoking should be told they are not licensed medicines but that they have helped “many people” quit.
Evidence suggests the devices are “substantially less harmful to health than smoking but are not risk-free” and knowledge of the long-term health impact is “still developing”, it adds.
E-cigarettes still do not feature on the approved list of stop-smoking aids, which should be made available to adults who smoke, in the guidance.
Nice said it had issued the advice because of “misconceptions and confusion about the safety of e-cigarettes”.
Professor Gillian Leng, deputy chief executive and director of health and social care at Nice, said: “Many people use e-cigarettes to help them stop smoking.
“The committee considered it likely that they are substantially less harmful than smoking.
“As a relatively new product, the long-term impact of their short-term use as well as the long-term health impact of their long-term use is still developing.
“The committee was concerned that people who smoke should not be discouraged from switching to e-cigarettes because the evidence is still developing.
“Our guidance, therefore, recommends that healthcare professionals help people make informed decisions on their use.”
Hazel Cheeseman, director of policy at Action on Health and Smoking, said: “As e-cigarettes are the most popular aid for quitting, it is good news that Nice recommends that health professionals should reassure smokers that they are substantially less harmful than smoking.
“Looking to the future, it is hoped that some e-cigarettes will be licensed as medicines and could then be prescribed, providing doctors with another tool to help smokers who want to quit.”
Alison Cook, director of policy at the British Lung Foundation, added: “Doctors and pharmacists should be very clear with people that there is a range of products available and that they can try vaping as a way to stop smoking.
“Information on vaping should be easily accessible.”