What Do We Know About E-cigarettes?

E-cigarettes are known by many different names and sometimes people find it hard to understand what is really known about them. Here we address some of the common questions people ask about e-cigarettes.

You can also find shortened versions of this information in our handouts for parents and youth:

What are e-cigarettes?

E-cigarettes are known by many different names, including e-cigs, electronic nicotine delivery systems (ENDS), alternative nicotine delivery systems (ANDS), e-hookahs, mods, vape pens, vaporizers, vapes and tank systems.  JUUL is one brand of e-cigarette.

Even though e-cigarettes do not contain any tobacco, the Food and Drug Administration (FDA) classifies them as “tobacco” products.

E-cigarettes are available in many shapes and sizes. E-cigarettes can look like cigarettes, cigars, pipes, pens, USB flash drives, or may be in other forms.

E-cigarettes include a battery that turns the device on, a heating element that heats the e-liquid and turns it into a vapor, a cartridge or tank that holds the e-liquid, and a mouthpiece or opening used to inhale the vapor.

What is vaping?

The word “vaping” refers to inhaling the “vapor” of an e-cigarette.

What is JUUL or JUULing?

“JUULing” refers to using one brand of e-cigarette called JUUL, which is popular among kids, teenagers and young adults. JUULs are small, sleek, high tech-looking, and easy to hide. They look like USB flash drives and can be charged in a computer. JUULs can be hidden in the palm of the hand and are hard to detect because they give off very little vapor or smell. Kids and teenagers are known to use them in school restrooms and even in the classroom.

How do e-cigarettes work?

E-cigarettes heat a liquid – called e-liquid or e-juice – to turn it into an aerosol or vapor. E-cigarette users inhale the vapor into their lungs.

Do e-cigarettes (including JUULs) contain nicotine?

The e-liquid in most e-cigarettes contains nicotine, the same addictive drug that is in regular cigarettes, cigars, hookah, and other tobacco products. However, nicotine levels are not the same in all types of e-cigarettes, and sometimes product labels do not list the true nicotine content.

The e-cigarette brand JUUL has a higher amount of nicotine per puff than some other types of e-cigarettes and cigarettes. Because of this, JUUL and JUUL-like products may be more addictive than other types of e-cigarettes. Some reports say kids have become physically dependent on nicotine by using JUULs.

There are some e-cigarette brands that claim to be nicotine-free but have been found to contain nicotine.

What is in the aerosol (vapor) of an e-cigarette?

Although the term “vapor” may sound harmless, the aerosol that comes out of an e-cigarette is not water vapor and can be harmful. E-cigarette vapor can contain substances that are addictive and can cause lung disease, heart disease, and cancer.

It is important to know that most e-cigarettes contain nicotine. There is evidence that nicotine harms the brain development of teenagers. If used during pregnancy, nicotine may also cause premature births and low birthweight babies.

Besides nicotine, e-cigarettes and e-cigarette vapor contain propylene glycol and/or vegetable glycerin. These are substances used to produce stage or theatrical fog which have been found to increase lung and airway irritation after concentrated exposure.

In addition, e-cigarettes and e-cigarette vapor may contain the chemicals or substances listed below.

  • Volatile organic compounds (VOCs): At certain levels, VOCs can cause eye, nose and throat irritation, headaches and nausea, and can damage the liver, kidney and nervous system.
  • Flavoring chemicals: Some flavorings are more toxic than others. Studies have shown that flavors contain different levels of a chemical called diacetyl that has been linked to a serious lung disease called bronchiolitis obliterans.
  • Formaldehyde: This is a cancer-causing substance that may form if e-liquid overheats or not enough liquid is reaching the heating element (known as a “dry-puff”).

The FDA does not currently require e-cigarette manufacturers to stop using potentially harmful substances. And, it is difficult to know exactly what chemicals are in an e-cigarette because most products do not list all of the harmful or potentially harmful substances contained in them. Some products are also labeled incorrectly.

What are the health effects of e-cigarettes?

E-cigarettes are still fairly new, and more research is needed over a longer period of time to know what the long-term effects may be. The American Cancer Society is closely watching for new research about the effects of using e-cigarettes and other new tobacco products. (See "What is in the aerosol (vapor) of an e-cigarette?" and "Do e-cigarettes (including JUULs contain nicotine?)"

Is e-cigarette use less harmful than smoking regular cigarettes?

Research has found that e-cigarette use is likely to be significantly less harmful than smoking regular cigarettes. This is because -e-cigarettes do not contain or burn tobacco – a process that produces an estimated 7,000 chemicals, including at least 70 chemicals that cause cancer – but the health effects of long-term use are not known.  (See "What is in the aerosol (“vapor”) of an e-cigarette?")

What is known about the use of e-cigarettes by youth?

No youth, including middle schoolers and high schoolers, should use e-cigarettes. (See "Is e-cigarette use less harmful than smoking regular cigarettes?" and "What is in the aerosol (“vapor”) of an e-cigarette?")

It is important to know that most e-cigarettes contain addictive nicotine. There is evidence that nicotine harms the brain development of teenagers.

Studies have shown that vaping by youth is strongly linked to later use of regular cigarettes and other tobacco products. Using e-cigarettes may play a part in a kid or teenager wanting to experiment with other, more harmful tobacco products.

Current e-cigarette use in youth dramatically increased in one year, according to the CDC and FDA.

  • In high school students, current e-cigarette use went from 11.7% in 2017 to 20.8% in 2018, an increase of 78%.
  • In middle school students, current e-cigarette use went from 0.6% in 2017 to 4.9% in 2018, an increase of 48%.

 JUUL is now the overwhelming favorite e-cigarette product among young people. Kids and teenagers are known to use them in school restrooms and even in the classroom.

The FDA has authority to regulate all tobacco products, including e-cigarettes and is working on several options to prevent youth access to e-cigarettes.

Does e-cigarette use cause cancer?

Scientists are still learning about how e-cigarettes affect health when they are used for long periods of time. It’s important to know that e-cigarette vapor contains some cancer-causing chemicals, although in significantly lower amounts than in cigarette smoke.

Can e-cigarettes explode?

There have been reports of e-cigarettes exploding and causing serious injuries. Usually the explosions are caused by faulty batteries or because the batteries were not handled as they should be. Visit the Food and Drug Administration website for safety tips to help avoid an e-cigarette battery explosion.

Is exposure to secondhand e-cigarette aerosol harmful?

Although e-cigarettes do not give off smoke like tobacco cigarettes, they do expose people to secondhand vapor that may contain harmful substances. Scientists are still learning about being exposed to secondhand e-cigarette vapor. So far, research shows that secondhand vapor exposure is likely to be less harmful than secondhand cigarette smoke.

The smoke-free and tobacco-free policies at schools, businesses, healthcare institutions, and other organizations should also cover e-cigarettes. This will help non-users avoid being exposed to potentially harmful e-cigarette vapor.

Can e-cigarettes help people quit smoking (known as smoking cessation)?

E-cigarettes are not currently approved by the FDA as aids to help stop smoking. Research findings have been mixed, but some studies show that e-cigarettes may be about as helpful as nicotine replacement therapies (NRT) (such as patches, gums, and lozenges) without counseling. More research is needed.

Safe and effective ways to help people quit smoking include FDA-approved medications that are used with counseling. However, we know that some smokers will not try to quit and will not use approved medications. In such cases, the American Cancer Society encourages these individuals to completely switch from regular cigarettes to e-cigarettes and then do their best to eventually quit all tobacco products, including e-cigarettes.

Some smokers choose to use both cigarettes and e-cigarettes at the same time on an ongoing basis, whether they are trying to quit or not. This is known as “dual use.” The dual use of e-cigarettes and tobacco cigarettes can cause significant harm because smoking any amount of regular cigarettes is very harmful. Therefore, people who are using both are strongly encouraged to completely stop smoking regular cigarettes.  

Where can I find more information about e-cigarettes?

To learn more about e-cigarettes, here are resources from the American Cancer Society and the FDA.

To learn more about tobacco and its health effects, see Tobacco and Cancer.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Centers for Disease Control and Prevention (CDC), National Center for Chronic Disease Prevention and Health Promotion, and Office on Smoking and Health. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. 2010. Publications and Reports of the Surgeon General. Atlanta (GA): Centers for Disease Control and Prevention (US). Accessed at http://www.ncbi.nlm.nih.gov/books/NBK53017/
on November 15, 2018.

Cullen KA, Ambrose BK, Gentzke AS, Apelberg BJ, Jamal A, King BA. Use of Electronic Cigarettes and Any Tobacco Product Among Middle and High School Students: United States, 2011–2018. Morbidity and Mortality Weekly Report. Nov 2018;67(45): 1276-1277. Accessed at https://www.cdc.gov/mmwr/volumes/67/wr/mm6745a5.htm?s_cid=mm6745a5_w
on November 15, 2018.

Drope J, Cahn Z, Kennedy R, Liber AC, Stoklosa M, Henson R, Douglas CE, Drope J. Key Issues Surrounding the Health Impacts of Electronic Nicotine Delivery Systems (ENDS) and Other Sources of Nicotine. CA: A Cancer Journal for Clinicians. 2017;87(6):449-471. Accessed at https://doi.org/10.3322/caac.21413
on November 15, 2018.

Food and Drug Administration (FDA). Statement from FDA Commissioner Scott Gottlieb, M.D., on proposed new steps to protect youth by preventing access to  flavored tobacco products and banning menthol in cigarettes. November 2018. Accessed at https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm625884.htm
on November 15, 2018.

Jidong, H, Duan, Z, Kwok, J, Binns S, Vera LE, Kim Y, Szczypka G, Emery SL. Vaping versus JUULing: How the Extraordinary Growth and Marketing of JUUL Transformed the US Retail e-Cigarette Market. Tobacco Control. May 2018, Accessed at https://doi.org/10.1136/tobaccocontrol-2018-054382 on November 15, 2018.

Moline, JM, Golden, AL, Highland, JH, Wilmarth, KR, & Kao, AS. Health effects evaluation of theatrical smoke, haze, and pyrotechnics. 2000. Prepared for Actor’s Equity Pension and Health Trust Funds. Accessed at https://www.actorsequity.org/resources/Producers/safe-and-sanitary/smoke-and-haze/
on November 15, 2018.

National Academies of Sciences, Engineering, and Medicine (NASEM). Public Health Consequences of E-Cigarettes. Eaton DL, Kwan LY, Stratton K, eds. 2018. Washington, DC: National Academies Press. Accessed
at https://doi.org/10.17226/24952 on November 15, 2018.

U.S. Department of Health and Human Services, Office of the Surgeon General. E-Cigarette Use Among Youth and Young Adults: A Report of the Surgeon General. 2016. Accessed at https://e-cigarettes.surgeongeneral.gov/documents/2016_SGR_Full_Report_non-508.pdf
on November 15, 2018.

Varughese S, Teschke, K, Brauer, M, Chow, Y, van Netten, C, & Kennedy, SM. Effects of theatrical smokes and fogs on respiratory health in the entertainment industry. American Journal of Industrial Medicine. 2005;47(5):411-418. 

Last Medical Review: November 15, 2018 Last Revised: April 18, 2019

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