E-cigarettes are not effective at helping people quit smoking in the long run, according to new research.

After a month of switching from tobacco to e-cigarettes, the electronic devices did help smokers kick the habit.

But three to six months later, users started smoking again.

In fact, e-cigarettes were no better than nicotine patches or a dummy e-cigarette, but with more harmful side-effects affects, researchers said.

E-cigarettes are not effective at helping people quit smoking in the long run, according to new research

In light of the findings, experts have today advised smokers wanting to quit to try more established methods, like patches or smoking cessation services before using e-cigarettes, until more research is carried out into whether they work.

The electronic devices vaporize nicotine and the user inhales the vapour, allowing them to consume nicotine while avoiding the harm caused by tobacco smoke.

However, the study found the devices caused adverse affects including dry cough, throat irritation, and shortness of breath.

People using e-cigarettes were also more likely to suffer serious problems such as lung inflammation and irregular heart beat compared with using a nicotine patch, LiveScience reports.

The findings were from an analyses of 22 studies looking into the safety of e-cigarettes, whether they could help people quit smoking, and their side effects.

Researchers pooled data on a total of 2223 people.

Lead author Dr Riyad al-Lehebi, of the University of Toronto, said nicotine patches and other aids to help people quit should be used if there is no evidence e-cigarettes help people kick the habit.

E-cigarette users took up smoking again within six months, and the devices caused side effects like a dry cough, throat irritation and shortness of breath (file photo)

He said: 'Although e-cigarettes are widely promoted and used as a smoking cessation tool, we found no data supporting their long-term efficacy and safety.

'While e-cigarettes have been shown to significantly improve abstinence at one month compared with placebo, no such evidence is available supporting their effectiveness for longer periods.

We would encourage smokers who wish to quit to first try more well-established methods like smoking cessation services Dr Penny Woods, chief executive of the British Lung Foundation

'Until such data are available, there are a number of other smoking cessation aids available that have a more robust evidence base supporting their efficacy and safety.'

He added: 'Given the potential health risks of using these unproven and unregulated devices, individuals seeking help with quitting smoking should consider other more well-established options until more research is performed.'

Dr Penny Woods, chief executive of the British Lung Foundation, said: 'Smoking remains the number one cause of preventable death in the UK, and we would encourage smokers who wish to quit to first try more well-established methods like smoking cessation services.

'E-cigarettes are likely to be much less harmful then smoking conventional cigarettes so people who can switch using e-cigarettes have taken a big step forward.

'However, the use of e-cigarettes is still relatively new, and these studies serve as a reminder that there may be potential risks attached to the long-term use of e-cigarettes so users, especially those living with a lung condition such as COPD and asthma, should try to quit them too.

'Some flavours may be more harmful than others and so more research is needed in this area to fully understand their risks'.

The study was presented at the American Thoracic Society International Conference in Denver.