Consultant psychiatrist Adam Winstock said people can take up vaping as a 'substitute' for tobacco and need more help to beat their nicotine habit.
The professor at University College London called for vapers to be given the same support as smokers who turn to the NHS to help quit cigarettes.
He added that while vaping is less damaging to health, smokers should try to quit both rather than simply moving to e-cigarettes.
"While most other forms of nicotine replacement were designed as a transition from using nicotine to not using nicotine, for some people vaping simply becomes a substitute," said Professor Winstock.
He warned that vapers may end up taking in higher levels of nicotine as more is delivered to users with this method.
"There isn't that same easy way of knowing how many vapes you've had a day compared to cigarettes," said the professor.
"I think there will be some people who will continue, and possibly escalate, their nicotine dependence.
"Is that a problem? It's better than smoking. But people who switch should have at the back of their mind that their transition to vaping should be considered temporary, anywhere from a month to six months."