Vaping health effects

E-cigarette use has clear negative impacts on health and is not harmless. Based on multiple systematic reviews and authoritative consensus from 2025 to 2026, its health risks have been widely confirmed, covering aspects such as the respiratory system, cardiovascular system, cancer risk, oral health, and the development of the adolescent brain.

Respiratory system health
There is sufficient evidence to support the damage of e-cigarettes to the respiratory system.

Increased risk of respiratory symptoms: A systematic review and meta-analysis in 2025 showed that current e-cigarette users had a 1.90 times higher risk of respiratory symptoms compared to never users (RR = 1.90, 95% CI: 1.28 - 2.83).

Increased risk of asthma and COPD: An umbrella review in 2025 combined 69 systematic reviews and found that e-cigarette use was associated with an increase in asthma incidence (OR = 1.30) and was related to an increased risk of chronic obstructive pulmonary disease (COPD). Another meta-analysis also pointed out that the risk of COPD was higher in e-cigarette users.

Comparison with traditional cigarettes: It is notable that the risk of respiratory symptoms in e-cigarette users is lower than that of traditional cigarette smokers (RR = 0.75, 95% CI: 0.64 - 0.89), but the risk is significantly higher in dual users.

Cardiovascular system health
The impact of e-cigarettes on the cardiovascular system is not fully clarified, but there are clear risk signals.

Abnormal physiological indicators: The summary analysis of the umbrella review indicated that e-cigarette use was associated with increased heart rate (mean difference = 1.41 beats/min), systolic blood pressure (mean difference = 0.51 mmHg), and diastolic blood pressure (mean difference = 0.59 mmHg), along with endothelial dysfunction and increased platelet activity.

Disease risk: Evidence cited in commentary articles showed that e-cigarette users had an increased risk of myocardial infarction and chronic obstructive pulmonary disease (COPD). A 2026 study further pointed out that the cardiovascular disease risk of dual users was higher than that of single smokers.

Cancer risk
E-cigarettes are likely to be carcinogenic, as their aerosol contains multiple carcinogenic substances.

Exposure to carcinogens: A 2026 commentary pointed out that e-cigarettes expose users to various harmful substances such as nicotine, volatile organic compounds, nitrosamines, toxic metals, and carbonyl compounds, which are related to cardiovascular and pulmonary dysfunction, oxidative stress, inflammation, DNA damage, and carcinogenic pathways. A systematic review in 2025 also confirmed that e-cigarette use was associated with an increased risk of lung cancer, especially in dual users.

Biological markers: Some studies have found evidence of carcinogens in the urine of e-cigarette users.

Oral health
The harm of e-cigarettes to oral health is multifaceted.

Increased risk of dental caries: A systematic review and meta-analysis in 2025 concluded that e-cigarette users may have a higher prevalence of dental caries compared to non-smokers. The study suggested that e-cigarettes may inhibit the normal oral microbiota, creating conditions for the growth of cariogenic bacteria.

Impaired periodontal health: The umbrella review pointed out that nine studies reported the negative impact of e-cigarettes on periodontal health.

Adolescent brain development and mental health
Adolescents are a sensitive group for the harm of e-cigarettes, and their impact is particularly profound.

Brain development and addiction: Animal studies have shown that exposure to nicotine vapor during adolescence leads to a significant increase in the excitability of neurons in the medial prefrontal cortex (mPFC), a brain region closely related to adolescent nicotine dependence. A review in 2026 also emphasized that exposure to nicotine during adolescence leads to persistent addictive vulnerability.

Mental health issues: Data from American teenagers in 2024 showed that among current e-cigarette users, 42.1% reported moderate to severe depression and anxiety symptoms, while the proportion for non-users or former users was only 21.0%. The evidence from systematic reviews also pointed out that e-cigarette use is associated with adverse mental health, risky or antisocial behaviors (including substance use through portals) and development.

Effectiveness of quitting smoking: Conditional tools
The role of e-cigarettes in quitting smoking needs to be strictly defined.

Evidence as a quitting tool: The updated Cochrane systematic review in 2025 provided high certainty evidence, indicating that nicotine-containing e-cigarettes compared to nicotine replacement therapy (NRT, such as patches) can increase the smoking cessation rate (RR = 1.55, 95% CI: 1.28 - 1.88). This means that under professional supervision, it may be helpful for some adult smokers.

Key limitations: This benefit is only applicable to adult smokers who have completely switched from traditional cigarettes to e-cigarettes. E-cigarettes are not a harmless product and should not be recommended to non-smokers, especially teenagers.

The greatest risk: Dual use
Using traditional cigarettes and e-cigarettes simultaneously (dual use) is the riskiest behavioral pattern.

Equivalent exposure level to smoking: A study by the American Cancer Society in 2025 found that the levels of tobacco-specific nitrosamines and volatile organic compounds in dual users were the same as those of only smoking traditional cigarettes, meaning that their potential risks of cancer, cardiovascular, respiratory, and reproductive/developmental hazards were not reduced.

Higher disease risk: Multiple analyses consistently indicated that dual users have a consistently higher risk in multiple health outcomes such as cardiovascular disease, stroke, asthma, and COPD compared to non-smokers. For example, one analysis showed that the risk of COPD for dual users was 3.86 times that of non-users (RR = 3.86, 95% CI: 1.49 - 10.02).

Summary
The health risks of vaping are real and multifaceted. It is not harmless vapor; its aerosol contains carcinogens and toxic metals, which can cause respiratory symptoms, abnormal cardiovascular function, oral health problems, and increase the risk of cancer. For teenagers, it also harms brain development and is associated with mental health issues. Although for adult smokers who wish to quit smoking, a complete switch to vaping under professional guidance may be a harm-reducing option, dual use would negate any potential benefits and maximize the health risks.