Dentists say they are seeing some side effects of vaping, such as bad breath, ulcers, soreness in some areas and a dry mouth. This could lead to a lack of saliva and, potentially, tooth decay.
David Thickett, professor of respiratory medicine at the University of Birmingham, is worried about the effects of delivering high doses of nicotine to the lungs through vaping. Although nicotine gums and patches have been used for many years to relieve cigarette cravings and are considered safe, he can't be so sure about nicotine in vaping. In a study in the lab, vaping was found to damage important immune system cells in the lungs, and cause inflammation.
More research is needed on people who vape to confirm the findings, but some of the effects were similar to those seen in regular smokers and people with chronic lung disease.
Prof Thickett warns that vapers don't always receive enough support to wean themselves off nicotine after switching to e-cigarettes.
He said e-cigarettes were safer than traditional cigarettes, but they could still be harmful in the long term and research was still in its early stages.