E-cigarettes are devices that allow users to breathe in vapor that may contain nicotine, flavorings, or chemicals from marijuana. E-cigarettes are also known as vapes or electronic nicotine delivery systems (ENDS). They may look like regular cigarettes, cigars, pipes, flashlights, USB flash drives, or pens.

E-cigarettes contain harmful substances that can cause cancer or life-threatening lung conditions such as EVALI (e-cigarette or vaping product use-associated lung injury). Because of these and other health risks, experts generally advise people not to use e-cigarettes.

An e-cigarette has three parts. It has a battery, a heating device, and a cartridge or tank. The part that heats up is called an atomizer. To use it, you put in a cartridge or fill the tank with a liquid. This liquid may contain different substances, such as:

• Nicotine.
• THC and CBD oils, both active ingredients in marijuana.
• Other substances and additives.

The type of substances in the liquid, and the amounts, may vary with each product. One of the dangers of e-cigarettes is that users often don't know what is actually in the liquid.

When the e-cigarette is puffed, the atomizer heats up. It turns the liquid in the tank or cartridge into a vapor (aerosol). You then breathe in this vapor. This is called vaping. It mimics real cigarette smoking. Other people nearby can also breathe in this vapor. Secondhand vapor is harmful to others, especially in closed spaces such as a car.

These are some things to consider about e-cigarettes and vaping.

• They can cause serious lung conditions. The vapor made by vaping contains harmful chemicals. There have been cases of lung disease and death related to vaping. EVALI is a chemical injury to the lungs. Other lung conditions include bronchiolitis obliterans (popcorn lung), lipoid pneumonia, and a collapsed lung.
• Vaping products often have nicotine. Nicotine is addictive. It can be hard to stop using it. Nicotine can be harmful to developing brains, such as in fetuses, children, and young adults. It is also not safe for those who are pregnant. At high doses, nicotine can cause dizziness and vomiting. Liquid nicotine can be poisonous if swallowed or spilled on skin. Keep it out of children's reach.
• E-cigarette products may not list all of the ingredients. It's hard to know exactly what chemicals are in an e-cigarette. It can also be hard to know their amounts.
• Vaping can expose those around you to secondhand aerosol. There is a concern about possible health risks from secondhand aerosol.
• Vaping devices can catch fire or explode. This can cause burns or injuries.

E-cigarette products that have been modified or bought from a place other than a store can be even less safe. They are more likely to contain unknown amounts of THC, CBD, and other harmful things. Illegal substances may also have been added.

Some of the people who became sick after vaping had symptoms of severe lung disease. These symptoms can occur slowly over a few days or weeks. They may become so serious that you need to be in a hospital. Call your doctor right away if you use e-cigarettes and have these symptoms:

• Cough, shortness of breath, or chest pain
• Nausea, vomiting, or diarrhea
• Extreme tiredness (fatigue)
• Fever of 100.4ºF (38°C) or higher

Some people try to quit smoking by reducing the amount of nicotine they breathe in. They do this slowly over time. If you're thinking of using e-cigarettes to help you stop smoking, talk to your doctor first. Here are some things to think about.

• Using e-cigarettes may not be safe. Some people have had serious lung problems from e-cigarette use. And the long-term effects aren't known.
• It's not approved as a quit-smoking aid. Counseling, medicines, and nicotine replacement products such as patches or gums are preferred.
• Some people end up using both. This is called dual use. Some people choose to use e-cigarettes when they can't smoke. But they may still smoke cigarettes.
• Quitting e-cigarette use comes with its own problems. These devices are often more socially acceptable than smoking and easier to do unnoticed (such as at work). Nicotine levels in cartridges can vary. This may lead you to take in more nicotine than you realize. These factors can make stopping even harder.

A number of tools can help you quit smoking. These have been approved by the FDA and CDC. You can also call 800-QUIT NOW (800-784-8669) or text QUITNOW to 333888.