People are almost twice as likely to succeed in quitting smoking if they use e-cigarettes than if they rely on nicotine replacement patches and gums, a new study has shown.

The research, focused on nearly 900 long-term smokers seeking NHS help to quit, was hailed as a landmark by experts in public health in the UK who believe e-cigarettes have already helped bring down the smoking rate. However, there was less enthusiasm in the United States, where there is concern that vaping nicotine is addictive and may cause children to start smoking.

Prof Peter Hajek from Queen Mary University of London led a randomised controlled trial to establish whether e-cigarettes were a better aid to quitting than nicotine replacement therapy. Their research is published in the New England Journal of Medicine. The mostly middle-aged smokers were randomly assigned to be given an e-cigarette starter kit or nicotine replacement therapy such as patches, lozenges, sprays or gum. All were given behavioural support. At the end of the year, 18% of the vapers were no longer smoking , compared with almost 10% of the others.

It is the first trial to compare the licensed quitting aids with e-cigarettes, which are not licensed for medical use. Hajek believes the results could change the advice smokers are given.

“Although a large number of smokers report that they have quit smoking successfully with the help of e-cigarettes, health professionals have been reluctant to recommend their use because of the lack of clear evidence from randomised controlled trials. This is now likely to change,” he said.

The early problems smokers experience when trying to give up, such as irritability and inability to concentrate, were lower in those using e-cigarettes. Vapers reported more throat and mouth irritation, but nicotine replacement therapy users reported more nausea.

At the end of the year, nearly 80% – the vast majority – of those using e-cigarettes were still vaping, whereas only 9% of the other group were still using gum and other forms of nicotine replacement therapy.

“I think one can see it as potentially problematic and also potentially beneficial,” said Hajek. “There are both sides to it and I think the beneficial side is stronger. The negative one is they are still using something and e-cigarettes are unlikely to be totally safe. They are unlikely to have more than about 5% of the risks of smoking but there is still some risk and if using it for one year means that they are using it for 30 years and if that generates some health risk then they would be better off not using it.

“Now the positive aspect is that we know from studies of nicotine replacement therapy that some heavy smokers need that crutch for longer to protect them from relapse.

“They will get quite a bit of benefit in that they will avoid feeling miserable and having urges to smoke and feeling there is something missing in their life and they will not put on weight, which these type of heavy smokers do, which puts them at risk of diabetes and so on.”

Public Health England and many UK scientists involved in tobacco research have strongly supported the potential of e-cigarettes to help people quit.

“This landmark research shows that switching to an e-cigarette can be one of the most effective ways to quit smoking, especially when combined with face-to-face support. All stop-smoking services should welcome smokers who want to quit with the help of an e-cigarette,” said Martin Dockrell, tobacco control lead at Public Health England.

“Smokers trying to quit have been choosing e-cigarettes over other types of support for some time. The research indicates that health professionals and Stop Smoking services should reach out to smokers who want to use e-cigarettes and support them in making this life-changing step,” said Prof Ann McNeill from Kings College London.

Prof Robert West from University College London said the study was “of huge significance. It provides the clearest indication yet that e-cigarettes are probably more effective than products such as nicotine gum and patches. It fits previously published trend data showing an increase in quit success rates in England and the US linked to more people using e-cigarettes.”

All agreed that more research is needed into the long-term potential harms of e-cigarettes.

But a comment paper on the study in the journal by US scientists takes a more cautious view. Belinda Borrelli and George T O’Connor from the Henry M. Goldman school of dental medicine at Boston University say the possibility of long-term harms – and the fear that children will learn addictive behaviours by watching adults vaping – mean that e-cigarettes should not be tried ahead of nicotine therapy products licensed by the US Food and Drug Administration (FDA).

“We recommend that e-cigarettes be used only when FDA-approved treatments (combined with behavioural counselling) fail, that patients be advised to use the lowest dose needed to manage their cravings and that there be a clear timeline and ‘off ramp’ for use,” they write.