E‑cigarettes are neither healthy nor harmless. Compared with traditional cigarettes, they probably contain fewer harmful substances because they do not burn tobacco. However, they can still deliver nicotine and other substances that burden the lungs, blood vessels and heart.
They may make sense mainly for adult smokers who completely stop smoking traditional cigarettes. For non‑smokers, children and adolescents, they offer no benefit and may lead to nicotine addiction.
What is an e‑cigarette, and how does it work?
An e‑cigarette is a device that allows a person to inhale an aerosol, with or without nicotine. In everyday language, terms such as e‑cigarette, vape or vaping device are often used. The principle is similar across these products. The device does not ignite tobacco like a traditional cigarette. Instead, it heats a liquid known as an e‑liquid or refill.
This creates an aerosol that the user inhales into the lungs. Unfortunately, this is not harmless “water vapour”. The CDC states that aerosol from e‑cigarettes may contain nicotine, ultrafine particles, volatile organic compounds, heavy metals, chemicals associated with cancer risk and other potentially harmful compounds.
How does an e‑cigarette work?
When the user inhales or presses a button, the battery activates a heating element. This heats the e‑liquid and creates an aerosol. The person then inhales it, in a similar way to cigarette smoke.
The difference is that, with a traditional cigarette, smoke is produced by burning tobacco. With an e‑cigarette, aerosol is produced by heating a liquid. The absence of combustion is the main reason e‑cigarettes usually contain fewer harmful substances than traditional cigarettes. However, this does not mean they are safe.
An e‑cigarette is not the same as heated tobacco
It is important to distinguish e‑cigarettes from heated tobacco products, such as IQOS. In e‑cigarettes, a liquid is heated. In heated tobacco products, tobacco material is heated. Both types of product can deliver nicotine and are often presented as alternatives to smoking, but they are not the same in terms of technology or composition.
What substances do e‑cigarettes and e‑liquids contain?
Aerosol from e‑cigarettes may contain nicotine, carcinogenic chemicals, ultrafine particles, heavy metals such as nickel, tin and lead, volatile organic compounds and flavourings. These may include diacetyl, which is associated with serious lung disease.
The base of e‑liquid is propylene glycol and glycerol
These substances help create the aerosol and affect how vaping feels. Glycerol usually creates a denser visible “vapour”, while propylene glycol can carry more flavour and produce a stronger throat hit.
Both substances are also used in other industries, including food, cosmetics and pharmaceuticals. However, this does not mean they are automatically safe for long‑term inhalation. The body processes substances differently when they are eaten compared with when they reach deep into the lungs.
Nicotine can lead to addiction
Many e‑cigarettes contain nicotine. This is the main addictive substance in tobacco and many nicotine products. Nicotine is not the main cause of lung cancer in traditional smoking, but it is central to the development and maintenance of addiction.
Nicotine acts on the brain’s reward system. After intake, a person may temporarily feel more focused, calmer or, conversely, more stimulated. The problem is that the brain becomes used to repeated nicotine intake. Over time, tolerance, cravings and withdrawal symptoms may develop. These can include irritability, restlessness, poorer concentration and a strong urge to vape again.
Flavourings
Flavourings are one of the main reasons e‑cigarettes are attractive. Tobacco, menthol, fruit, sweet, drink‑inspired and “ice” flavours, which create a cooling effect, are all common.
The problem is not only that flavourings make e‑cigarettes more appealing, especially to young people. The issue is also that a flavouring being safe to eat does not automatically mean it is safe to inhale.
The CDC explicitly warns that some flavourings used in e‑cigarettes may be safe when consumed, but not when inhaled, because the lungs process substances differently from the digestive tract. Diacetyl, a chemical associated with serious lung disease, is one example.
The European scientific committee has also concluded that flavourings significantly contribute to the appeal of e‑cigarettes and to experimentation or initiation. This is especially relevant for children and adolescents, for whom sweet and fruity flavours may reduce the perception of risk.
Substances formed during heating
E‑liquid is not simply a mixture of substances that turn unchanged into aerosol. New compounds can form during heating. Their amount depends on the specific device, power, temperature, composition of the refill and style of use.
Substances that may appear in the aerosol include:
aldehydes, such as formaldehyde, acetaldehyde and acrolein
volatile organic compounds
tobacco‑specific nitrosamines, if the nicotine source is tobacco
polycyclic aromatic hydrocarbons
metals released from device parts
ultrafine particles that can penetrate deep into the airways.
The amount of these substances is usually lower in e‑cigarettes than in traditional cigarette smoke. This is why e‑cigarettes are discussed as a potentially less harmful alternative to smoking. However, a lower amount of harmful substances does not mean they are safe.
Heavy metals from device parts
Aerosol from e‑cigarettes may also contain metals, such as nickel, tin or lead. These can be released from the heating coil or other metal parts of the device. The CDC lists these metals among the substances that may be present in e‑cigarette aerosol.
It is therefore not enough to evaluate only the e‑liquid itself. The resulting exposure also depends on the quality and construction of the device, the age of the coil, the heating temperature and the way the device is used.
Ultrafine particles – size matters
Aerosol from e‑cigarettes may contain very small particles. These matter because they can reach deep into the airways. The smaller the particles, the more easily they can penetrate into the more distant parts of the lungs.
This means that the lungs are repeatedly exposed to a chemical mixture that may contain nicotine, flavourings, particles and other substances.
E‑cigarettes vs. traditional cigarettes
The most important difference is that, in traditional cigarettes, tobacco is burned, while in e‑cigarettes, a liquid is heated.
The burning of tobacco is the main reason traditional cigarettes are so harmful. Combustion produces cigarette smoke, which contains thousands of chemicals. The CDC states that cigarette smoke contains a mixture of about 7,000 chemicals, while aerosol from e‑cigarettes generally contains fewer chemicals and in lower amounts. However, this does not mean that aerosol from e‑cigarettes is safe.
What happens when you smoke a traditional cigarette?
Nicotine in a cigarette is important mainly because it causes addiction. However, it is not the only or main reason smoking causes so many diseases. A large part of the health risk comes from substances formed during combustion, such as carbon monoxide, tar, polycyclic aromatic hydrocarbons, tobacco‑specific nitrosamines and other toxic or carcinogenic compounds. Traditional smoking therefore significantly increases the risk of lung cancer, chronic obstructive pulmonary disease, heart attack, stroke and other diseases.
What happens when using an e‑cigarette?
An e‑cigarette does not burn tobacco. It heats e‑liquid and creates an aerosol that the user inhales. As a result, fewer substances formed by combustion are usually produced. Research summarises that aerosol from e‑cigarettes contains fewer types of toxic substances and lower concentrations of most toxic substances than smoke from traditional cigarettes. At the same time, researchers warn that nicotine intake from e‑cigarettes can be comparable to traditional cigarettes in experienced users.
While e‑cigarettes typically reduce exposure to many harmful substances produced by combustion, they may not reduce nicotine exposure. Some modern e‑cigarettes, especially devices using nicotine salts, can deliver nicotine very efficiently.
Does "less harmful" automatically mean safe?
No. E‑cigarettes probably expose users to lower amounts of many toxic substances than traditional cigarettes. This is the main argument for their possible use in adult smokers who cannot quit otherwise and completely switch from traditional cigarettes to e‑cigarettes. Completely replacing traditional cigarettes with e‑cigarettes reduces exposure to many toxic and carcinogenic substances present in cigarette smoke.
The effect of vaping on lung health
From the perspective of the lungs, traditional cigarettes are worse. In comparative studies, cigarette smoke caused a more pronounced inflammatory response, pathological changes in the airways, destruction of alveoli and thickening of small airways. These are changes typical of the development of obstructive lung diseases.
E‑cigarettes usually caused these changes less markedly, but they were not neutral. Studies show that aerosol from e‑cigarettes can still reduce lung function, increase oxidative stress, alter the number of inflammatory cells in the lungs and affect the protective barrier of the airways. The lungs are less burdened by vaping than by smoking, but they are still not exposed to harmless vapour.
The effect of vaping on heart health
A similar picture appears for the heart and blood vessels. Traditional cigarettes have a more serious impact on the cardiovascular system, but e‑cigarettes also cause measurable changes. In studies, effects have included increased arterial stiffness, impaired endothelial function, changes in heart regulation, increased blood pressure, peripheral vasoconstriction and possible disruption of the vascular barrier in the brain.These effects were mostly weaker with e‑cigarettes than with cigarette smoke, but they still show that e‑cigarettes cannot be considered completely safe.
The effect of vaping on the adolescent brain
For adult smokers, the main question is often whether e‑cigarettes reduce exposure to harmful substances from tobacco smoke. For adolescents, the situation is different. It is often not about a “less harmful” substitute, but about the first regular contact with nicotine.
The adolescent brain is more sensitive to addictive substances. During adolescence, areas responsible for decision‑making, planning, impulse control and emotional regulation are still developing. Nicotine interferes with these processes and may increase the risk of longer‑term addiction.
The effect of vaping on cancer
For traditional cigarettes, the link to cancer is very well established. For e‑cigarettes, the situation is less clear because long‑term human data is still lacking. This does not mean the risk does not exist.
There is reason for caution. Some substances in e‑cigarette aerosol may have toxic or mutagenic effects. It has been reported that formaldehyde and acrolein in e‑cigarette aerosol are capable of causing DNA damage and mutagenesis, which supports the biological possibility of a long‑term carcinogenic risk.
E‑cigarettes may cause harm in different ways from traditional cigarettes
E‑cigarettes may not only cause harm in the same way as traditional cigarettes. Some studies show that they may also act through different biological mechanisms. For example, components of e‑liquid, such as propylene glycol and glycerol, may themselves contribute to observed effects.
The risk is further influenced by nicotine concentration, flavourings, device power, heating temperature and style of use. Higher device power has been associated in some studies with more pronounced genotoxic effects, meaning DNA damage. This is important because two e‑cigarettes may not pose the same risk. It depends on the specific product and how it is used.
Why does it matter who uses an e‑cigarette?
For an adult who smokes a pack of cigarettes a day and completely switches to an e‑cigarette, it may mean a reduced health risk. Not because the e‑cigarette is healthy, but because it replaces a much more harmful way of taking in nicotine: burning tobacco.
For someone who has never smoked, the situation is completely different. In this case, the e‑cigarette does not replace a more harmful product. Instead, it adds a new source of nicotine and other inhaled substances. For a non‑smoker, it makes no sense to say that an e‑cigarette is “healthier”. Healthier than what? Compared with not using any nicotine product, an e‑cigarette is clearly an unnecessary burden.
For children and adolescents, the problem is even more pronounced. Nicotine is addictive, and the young brain is more sensitive to its effects. Professional institutions therefore do not consider e‑cigarettes suitable for minors, non‑smokers or pregnant women.
Combining both is risky
Dual use, meaning smoking and vaping at the same time, can be very problematic in terms of risk.
E‑cigarettes alone are associated with moderate effects on oxidative stress, inflammation, endothelial dysfunction and cardiovascular changes. Traditional cigarettes are associated with more severe effects. Dual use, however, can lead to the most pronounced adverse impacts.
Why? Because the person continues to inhale smoke from burning tobacco while also adding aerosol from an e‑cigarette.
Dual use reduces the chance of quitting smoking
A systematic review from 2025 concluded that dual users of e‑cigarettes and traditional cigarettes have a lower probability of quitting smoking compared with people who smoke only traditional cigarettes. The authors also state that most dual users return to traditional smoking.
| Traditional cigarette | Electronic cigarette | |
| What is heated/burned | Tobacco is burned | E‑liquid is heated |
| What is inhaled | Smoke | Aerosol |
| Nicotine presence | Yes | Often yes |
| Addiction risk | High | High, if it contains nicotine |
| Combustion products | Yes, in high amounts | Significantly less, because there is no combustion |
| Number and amount of toxic substances | High | Usually lower than in cigarette smoke |
| Safety for non‑smokers | Not suitable | Not suitable |
| Suitability for children and adolescents | Not suitable | Not suitable |
More than a fifth of students vape regularly
European data confirm that e‑cigarettes are not a marginal phenomenon. ESPAD 2024 monitored 113,882 students aged 15–16 in 37 European countries. On average, 44% of students said they had tried an e‑cigarette at least once in their life. Current use, meaning use in the last 30 days, was reported by 22% of students.
It is also interesting to compare this with traditional cigarettes. Across Europe, an average of 18% of students reported smoking cigarettes in the last 30 days, while 22% reported current use of e‑cigarettes.
ESPAD also mentions that 60% of students consider e‑cigarettes fairly or very easy to access. This is concerning because, in many countries, these products should not be accessible to minors at all.
Why are e‑cigarettes attractive to young people?
E‑cigarettes differ from traditional cigarettes not only in technology, but also in appearance, taste and overall impression. Traditional cigarettes are now associated with smell, smoke and health warnings. E‑cigarettes, on the other hand, often appear modern, colourful, discreet and sometimes even “healthy”. This can reduce young people’s perception of risk.
They taste good
Flavourings play a big role. Fruit, sweet, menthol and “ice” variants may seem more like a sweet treat than a nicotine product. This is especially important for adolescents, who would often find traditional cigarette smoke unpleasant.
They are easy to use
Their appeal is also increased by how easy they are to use. Disposable e‑cigarettes do not need to be refilled or maintained. You simply unpack and use them. In 2024, according to the American NYTS survey, disposable products were the most commonly used type of e‑cigarette among young people, reported by 55.6% of users.
Marketing is not just about traditional advertising
Marketing includes packaging design, flavour names, social media content, influencers, videos, reviews and user‑generated content. Young people may therefore not perceive e‑cigarettes as a promoted nicotine product, but as part of a lifestyle.
They are easily accessible
According to the European ESPAD 2024 study, 60% of students aged 15–16 said it would be fairly or very easy for them to obtain e‑cigarettes.
Do e‑cigarettes help people quit smoking?
One of the most common arguments in favour of e‑cigarettes is that they can help people quit smoking.
The answer is not black and white. According to current data, nicotine e‑cigarettes can help some adult smokers quit traditional cigarettes. However, this does not mean they are suitable for non‑smokers, children, adolescents or pregnant women.
What do studies say?
A recent Cochrane review from 2025 states that nicotine e‑cigarettes help people quit smoking for at least six months more significantly than nicotine replacement therapy, such as patches or gum. The conclusion is rated as high‑certainty evidence. The review also states that nicotine e‑cigarettes probably help more than nicotine‑free e‑cigarettes and may work better than behavioural support alone or no support.
Bottom line
E‑cigarettes are neither healthy nor harmless. Compared with traditional cigarettes, they probably contain fewer toxic substances because tobacco is not burned when using them. However, this does not mean a person inhales only “water vapour”. Aerosol from e‑cigarettes may contain nicotine, flavourings, volatile substances, fine particles or metals that can burden the airways, blood vessels and heart.
The key is to distinguish who uses e‑cigarettes and what they are using them instead of. For an adult smoker who completely switches from traditional cigarettes to an e‑cigarette, vaping may be a less risky alternative. However, if a person smokes and vapes at the same time, the risks are often higher. For non‑smokers, children and adolescents, e‑cigarettes offer no benefit. On the contrary, they may increase the risk of nicotine addiction and other health problems.
