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E-cigarettes come in lots of shapes and sizes and are known by many different names. They are also a fairly new product. People sometimes find it hard to figure out what’s in them and whether they are safe to use.  

Here, we address some of the most common questions about e-cigarettes.

What are e-cigarettes?

E-cigarettes are known by many different names. This includes e-cigs, vapes, vape pens, electronic nicotine delivery systems (ENDS), alternative nicotine delivery systems (ANDS), e-hookahs, mods, vaporizers, and tank systems. E-cigarettes are also sometimes known by their brand names.

E-cigarettes are available in many shapes and sizes. They can look like cigarettes, cigars, pipes, pens, and USB flash drives. Or they can take other forms.

All e-cigarettes include a battery that turns the device on, a heating element that heats the e-liquid and turns it into an aerosol of tiny particles (sometimes called a “vapor”), a cartridge or tank that holds the e-liquid, and a mouthpiece or opening used to inhale the aerosol.

E-cigarettes don’t have tobacco, but many of them have nicotine, which comes from tobacco. Because of this, the U.S. Food and Drug Administration (FDA) classifies them as "tobacco products."

What is vaping?

The use of e-cigarettes is often called “vaping” because many people believe it creates a vapor that is inhaled. But in fact, e-cigarettes create an aerosol made up of tiny particles. This is different from a vapor.

How do e-cigarettes work?

E-cigarettes heat a liquid (called e-liquid, e-juice, or vape juice) and to turn it into an aerosol (sometimes called a "vapor").  When a person uses an e-cigarette, they inhale this aerosol into their lungs.

Do e-cigarettes contain nicotine?

The e-liquid in most e-cigarettes has nicotine, the same addictive chemical in regular cigarettes, cigars, hookah, and other tobacco products. But nicotine levels aren’t the same in all types of e-cigarettes. Sometimes, product labels don’t list the true nicotine content.

There is evidence that nicotine harms the brain development of teenagers. If nicotine is used during pregnancy, it can also cause premature births and low birthweight babies.

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

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

The term “vapor” might sound harmless. But the aerosol that comes out of an e-cigarette is not water vapor, and it can be harmful. The aerosol from an e-cigarette can contain nicotine and other substances that are addictive. These chemicals can also cause lung disease, heart disease, and cancer.

In addition to nicotine, e-cigarettes and e-cigarette vapor may also have these chemicals or substances:

Propylene glycol and/or vegetable glycerin

These are considered safe if they are ingested (eaten) or applied to skin. They have not been rated as safe to breathe in, and they may cause lung irritation and allergic reactions. In some situations, they may turn into cancer-causing chemicals. 

Volatile organic compounds (VOCs)

At certain levels, VOCs can cause eye, nose, and throat irritation, headaches, and nausea. They can damage the liver, kidneys, and nervous system.

One type of VOC is formaldehyde, which is known to cause cancer. Formaldehyde may form if e-liquid overheats, or if not enough liquid reaches the heating element (known as a “dry-puff”).

Flavoring chemicals

Some flavorings are more harmful than others. Studies show that some flavors have different levels of a chemical called diacetyl. Diacetyl has been linked to a serious lung disease called bronchiolitis obliterans, also known as popcorn lung.

The FDA does not currently require safety testing for all the substances in e-cigarettes. It's also hard to know exactly what chemicals are in an e-cigarette because most products don’t list everything that’s in them. Some products are also labeled incorrectly.

People who vape also need to check and make sure the products they buy haven’t been changed or modified. This can lead to exposure to possibly harmful or illegal substances from unknown sources and raise the risk of health problems, like lung damage.

What are the health effects of e-cigarettes?

E-cigarettes are still fairly new. More research is needed over a longer period of time before we can understand the long-term effects.

But even though the long-term health effects of e-cigarettes are not known, we do know that all tobacco products, including e-cigarettes, can pose health risks to people who use them.

For more information, see Health Risks of E-cigarettes.

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

No youth should use e-cigarettes or any tobacco product. This includes middle schoolers and high schoolers.  

Most e-cigarettes contain addictive nicotine. Nicotine can harm the brain development of teenagers.

According to the FDA 2024 National Youth Tobacco Survey, the use of e-cigarettes dropped among middle and high schoolers during the previous year. However, there are still millions of young people using these products on an ongoing basis.

Studies also show that young people who vape are more likely to become regular users of cigarettes and other, more harmful tobacco products.

The FDA has the authority to regulate all tobacco products, including e-cigarettes. The FDA is working on several options to prevent youth access to e-cigarettes. For example, federal law prohibits the sale of any tobacco product, including e-cigarettes, to anyone who is younger than 21 years of age.

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 the aerosol ("vapor") from an e-cigarette has some cancer-causing chemicals.

Can e-cigarettes explode?

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

Is exposure to secondhand e-cigarette aerosol harmful?

E-cigarettes expose people to secondhand aerosol or "vapor" that can contain harmful chemicals.

Scientists are still learning about the health effects of being exposed to secondhand e-cigarette aerosol. But the U.S. Surgeon General has said that e-cigarette aerosol is not harmless. Secondhand aerosol can expose others to nicotine and possibly to other harmful chemicals.

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 aerosol.

Can e-cigarettes help people quit using tobacco?

E-cigarettes are not approved by the FDA as aids to help people stop smoking. This is because there is not enough research to show they help people stop using tobacco.

On the other hand, there are other proven methods that can help you quit using tobacco. This includes FDA-approved nicotine replacement and other medicines. There is a lot of evidence showing that these methods work. They are safe and effective, especially when combined with counseling.

Some people choose to try e-cigarettes to help them stop smoking. But e-cigarettes have as much if not more nicotine as regular cigarettes and other tobacco products.

If you switch to e-cigarettes, you will still be dealing with nicotine and other health risks. And quitting e-cigarettes is just as hard as quitting other tobacco products.

Dual use of cigarettes and e-cigarettes

People who have switched completely from cigarettes to e-cigarettes should not switch back to smoking cigarettes (either solely or along with e-cigarettes). This could expose them to even worse health effects.

Some people who smoke use both cigarettes and e-cigarettes at the same time. This is known as “dual use.” The dual use of e-cigarettes and tobacco cigarettes can lead to significant health risks.

Recent research indicates that people who use both cigarettes and e-cigarettes have a higher risk of getting lung cancer than people who only use cigarettes.

People should not use both products at the same time and are strongly encouraged to completely stop using all tobacco products. 

Where can I find more information about e-cigarettes?

These resources can help you learn more about e-cigarettes: