Nicotine is highly addictive. Using e-cigarettes can cause addiction to nicotine.
The adolescent brain is more susceptible to nicotine addiction than fully developed brains of adults.
Nicotine delivered via e-cigarettes is less harmful than smoking tobacco cigarettes. When burned, the tobacco in conventional cigarettes releases thousands of harmful toxins and carcinogens which are the major causes of death and disease from tobacco.
Nicotine alters brain development.6 It can affect cognitive function, memory, and attention when used while the brain is still developing into the mid-20s.
There are no long-term data on the risks of nicotine delivered via e-cigarettes (e.g., heart, lungs, etc).
There are some preliminary data for cardiac effects. One small study in otherwise healthy volunteers (21 to 45 years) showed an association between users of e-cigarettes and a shift in cardiac autonomic balance toward sympathetic predominance and increased oxidative stress. Nicotine is absorbed in e-cigarette users. Approximate saliva concentration of a nicotine metabolite (cotinine):
E-cigarettes (average use 220 puffs/day; variable nicotine content): 353 ng/mL Tobacco cigarettes (26 per day): 340 ng/mL Nicotine patch 21 mg: 165 ng/mL Nicotine nasal spray, 24 doses per day: 150 ng/mL to 200 ng/mL E-cigarettes are a source of secondhand exposure to nicotine and other chemicals. The risks of secondhand vapor are unknown but are expected to be lower than tobacco smoke. Caution is recommended around non-users, youth, pregnant women, people with cardiovascular conditions, etc.
Analysis of common brands of e-cigarettes showed contents included propylene glycol, glycerol, flavoring, diethylene glycol, ethylene glycol, ethanol, formaldehyde, and acrolein. The effect of chronic exposure to these chemicals is not known.
The Canadian Lung Association warns that people who use e-cigarettes are inhaling unknown, unregulated, and potentially harmful substances.
The release of chemicals and contaminants in e-cigarette vapor varies between devices and the way they are used. More chemicals are released (e.g., formaldehyde [a known carcinogen], etc) at higher temperatures.
E-cigarette use has been linked to respiratory symptoms (cough, wheezing, etc).
There is one case report of a previously healthy 18-year-old diagnosed with hypersensitivity pneumonitis after e-cigarette use.