Medical providers should encourage traditional smoking cessation methods despite the availability of electronic cigarettes.
This is the advice given after a study by the Penn State College of Medicine.
Referring to the electronic cigarettes Jonathan Foulds, professor of public health sciences and psychiatry at the college, said they initially seem like a gimmick likely to be banned but the study showed some smokers are finding them useful.
"We just don't have enough information on their long-term safety and effectiveness for clinicians to recommend them," he added.
Electronic cigarettes work by providing smokers with nicotine but cut out tar and carbon monoxide inhalation.
Professor Foulds is also worried about a poor standard of quality control among electronic cigarettes.
The British Heart Foundation states 11 million smokers have already given up in the UK but most others want to.