E-cigarettes can help smokers stop or reduce their habit, a respected international review has confirmed.
The first Cochrane review to examine the products considered two randomised trials with data from 662 current smokers.
The review authors, from the UK and New Zealand, said the results needed to be expanded on by other studies.
Public health doctors said they remained concerned that the devices could reverse progress on smoking.
The trial researchers found that about 9% of smokers who used e-cigarettes were able to stop smoking for up to a year, and possibly longer.
That compared with about 4% of smokers who used devices which did not contain nicotine.
And in the two trials – regarded as “gold standard” evidence – 36% of e-cigarette users managed to halve the number of conventional cigarettes they smoked, compared with 28% who used placebo devices.
There was no evidence of serious adverse effects among people using e-cigarettes.
However, the Cochrane review authors cautioned that the results were limited by the small number of trials and the limited sample of participants.