A cigarette-like device that uses a battery to heat up a liquid solution, usually containing nicotine and flavorings, to produce an aerosol that the user inhales. The vapor can also contain tetrahydrocannabinol (THC, the active ingredient in marijuana) and other chemicals. E-cigarettes are often marketed to look like tobacco products and are popular among youth. The FDA monitors national usage rates, including surveys of youth use, and has taken a variety of actions to keep e-cigarettes and other ENDS out of the hands of youth.

Many e-cigarettes are flavoured with fruit or candy-like tastes that appeal to adolescents and young adults. The availability of these flavours and the marketing of e-cigarettes to youth have been identified as factors that contribute to high youth e-cigarette consumption. Despite their popularity, e-cigarettes are not proven to be effective as smoking cessation aids, and may be harmful for other reasons. In a recent report, long-term e-cigarette use was linked to impaired blood pressure regulation, endothelial dysfunction and vascular stiffness, all of which are associated with atherosclerosis and cardiovascular morbidity.

While some e-cigarettes only use water vapor to create the vapour, others include a range of chemical compounds that can be toxic to the lungs and other organs. For example, the flavouring diacetyl can cause lung damage called bronchiolitis obliterans, also known as popcorn lung, by causing permanent scarring of the small tubes that bring air in and out of the lungs. The e-liquids used in e-cigarettes may also contain dangerous metals and other substances such as silica particles, and the vapor can carry these into the mouth and throat.

Short-term e-cigarette use has been associated with cytotoxicity, oxidative stress and inflammatory responses in pulmonary epithelial cells. However, the toxicity of specific flavourings varies and is dependent on their concentration in the vapor and the way they are used or modified by the manufacturer. Moreover, mislabeling is a common problem in the e-liquid industry.

The chemistry of e-cigarettes varies by brand, but the most commonly used ingredients are propylene glycol and glycerol, also known as 1,2-propanediol and 1,2,3-triol, respectively. These chemicals are humectants, which help to maintain the consistency of the e-liquid and protect it from drying out.

These humectants can be toxic to human lungs at high concentrations and are a significant risk factor for COVID-19. They can induce inflammation in the lungs and interfere with cellular function by blocking the activity of some key enzymes. They can also affect the ability of the lungs to absorb oxygen, which can lead to respiratory distress and hypoxemia. The effects of the other chemicals in e-cigarettes and their long-term use have been little studied. The toxins in e-cigarettes can also lead to damage in other organs, such as the liver and kidneys. The FDA is currently evaluating the potential health risks of these new technologies. The more we learn about e-cigarettes, the better we can understand their effects and help to prevent youth use.電子煙