Most e-cigarettes contain nicotine. Nicotine is highly addictive and can harm adolescent brain development, which continues into the early to mid-20s.

E-cigarettes can contain other harmful substances besides nicotine.

Young people who use e-cigarettes may be more likely to smoke cigarettes in the future.

Using nicotine in adolescence can harm the parts of the brain that control attention, learning, mood, and impulse control.

Each time a new memory is created or a new skill is learned, stronger connections – or synapses – are built between brain cells. Young people’s brains build synapses faster than adult brains.

Nicotine changes the way these synapses are formed.

Some of the ingredients in e-cigarette aerosol could also be harmful to the lungs in the long-term. For example, some e-cigarette flavorings may be safe to eat but not to inhale because the gut can process more substances than the lungs.

The e-cigarette aerosol that users breathe from the device and exhale can contain harmful and potentially harmful substances, including:

Nicotine
Ultrafine particles that can be inhaled deep into the lungs
Flavoring such as diacetyl, a chemical linked to a serious lung disease
Volatile organic compounds
Cancer-causing chemicals
Heavy metals such as nickel, tin, and lead