Most e-cigarettes contain nicotine which is highly addictive and can harm adolescent brain development, but E-cigarettes can contain other harmful substances besides nicotine as well.
Young people who use e-cigarettes may also be more likely to smoke cigarettes in the future.
The bottom line is that the use of e-cigarettes is unsafe for kids, teens, and young adults.
For more information: https://www.cdc.gov/tobacco/basic_information/e-cigarettes/Quick-Facts-on-the-Risks-of-E-cigarettes-for-Kids-Teens-and-Young-Adults.html
Original source can be found here.