There are many types of e-cigarettes and e-hookahs. Most have a battery-operated heating device. When you inhale, the heater turns on and heats a liquid cartridge into a vapor. The cartridge may contain nicotine or other flavors or chemicals. It also contains glycerol or propylene glycol (PEG), which looks like smoke when you exhale. Each cartridge can be used a few times. Cartridges come in many flavors.

E-cigarettes and other devices also may be sold for use with tetrahydrocannabinol (THC) and cannabinoid (CBD) oils. THC is the component in marijuana that produces the "high."

The makers of e-cigarettes and e-hookahs market their products for several uses:

• To use as a safer alternative to tobacco products. The makers claim their products do not contain the harmful chemicals found in regular cigarettes. They say this makes their products safer choices for those who already smoke and don't want to quit.
• To smoke without getting addicted. Consumers can choose cartridges that do not contain nicotine, the addictive substance found in tobacco.
• To use as a tool to help you quit smoking. Some companies tout their products as a way to quit smoking. More studies are needed to prove this claim.

E-cigarettes have not been fully tested. So, it is not yet known if any of these claims are true.

Health experts have many concerns about the safety of e-cigarettes and e-hookahs.

Between August 2019 and January 2020, around 2,807 people were hospitalized due to lung injury from the use of e-cigarettes and other devices. Some people even died. This outbreak was linked to THC-containing e-cigarettes and other devices that included the additive vitamin E acetate. For this reason, the Centers for Disease Control and Prevention (CDC) and the US Food and Drug Administration (FDA) made the following recommendations:

• Do not use THC-containing e-cigarettes and other devices purchased from informal (non-retail) sources such as friends, family, or in-person or online dealers.
• Do not use any products (THC or non-THC) that contain vitamin E acetate. Do not add anything to e-cigarette, vaping, or other products you purchase, even from retail businesses.

Other safety concerns include:

• There is no evidence that shows these products are safe to use over the long term.
• These products can contain many harmful substances such as heavy metals and cancer-causing chemicals.
• The ingredients in e-cigarettes are not labeled, so it is not clear what's in them.
• It is not known how much nicotine is in each cartridge.
• It is not known if these devices are a safe or effective way to quit smoking. They are not approved as a quit-smoking aid.
• Non-smokers may start using e-cigarettes because they believe these devices are safe.

Many experts also have concerns about the effects of these products on children.

• These products are the most commonly used tobacco product in young people.
• These products are sold in flavors that may appeal to children and teens, such as chocolate and key lime pie. This could lead to more nicotine addiction in children.
• Teens who use e-cigarettes may be more likely to take up smoking regular cigarettes.

There is emerging information about e-cigarettes to suggest they are harmful. Until more is known about their long-term effects, the FDA and the American Cancer Association recommend steering clear of these devices.

If you are trying to quit smoking, your best bet is to use FDA-approved smoking cessation aids. These include:

• Nicotine gum
• Lozenges
• Skin patches
• Nasal spray and oral inhaled products

If you need more help quitting, talk with your health care provider.

Electronic cigarettes; Electronic hookahs; Vaping; Vape pens; Mods; Pod-Mods; Electronic nicotine delivery systems; Smoking - electronic cigarettes

American Lung Association website. E-cigarettes. www.lung.org/quit-smoking/e-cigarettes-vaping/lung-health. Updated May 31, 2023. Accessed May 3, 2024.

Centers for Disease Control and Prevention website. E-cigarettes (vapes). www.cdc.gov/tobacco/e-cigarettes/?CDC_AAref_Val=https://www.cdc.gov/tobacco/basic_information/e-cigarettes/index.htm. Updated May 15, 2024. Accessed June 7, 2024.

Gotts JE, Jordt SE, McConnell R, Tarran R. What are the respiratory effects of e-cigarettes? BMJ. 2019;366:l5275. PMID: 31570493 pubmed.ncbi.nlm.nih.gov/31570493/.

Rebuli ME, Rose JJ, Noël A, et al. The E-cigarette or Vaping Product Use-Associated Lung Injury Epidemic: Pathogenesis, Management, and Future Directions: An Official American Thoracic Society Workshop Report. Ann Am Thorac Soc. 2023;20(1):1-17. PMID: 36584985 pubmed.ncbi.nlm.nih.gov/36584985/.

Rice SJ, Hyland V, Behera M, Ramalingam SS, Bunn P, Belani CP. Guidance on the Clinical Management of Electronic Cigarette or Vaping-Associated Lung Injury. J Thorac Oncol. 2020;15(11):1727-1737. PMID: 32866653 pubmed.ncbi.nlm.nih.gov/32866653/.

Schier JG, Meiman JG, Layden J, et al. Severe pulmonary disease associated with electronic-cigarette-product use - Interim Guidance. MMWR Morb Mortal Wkly Rep. 2019;68(36):787-790. PMID: 31513561 pubmed.ncbi.nlm.nih.gov/31513561/.

US Food and Drug Administration website. E-cigarettes, vapes, and other electronic nicotine delivery systems (ENDS). www.fda.gov/tobacco-products/products-ingredients-components/e-cigarettes-vapes-and-other-electronic-nicotine-delivery-systems-ends. Updated April 12, 2024. Accessed May 3, 2024.

US Food and Drug Administration website. Lung injuries associated with use of vaping products. www.fda.gov/news-events/public-health-focus/lung-injuries-associated-use-vaping-products. Updated April 13, 2020. Accessed June 17, 2024.

Updated by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.