# Time- and Dose-Dependent Cardiovascular Effects of Nicotine-Containing Electronic Cigarettes in Young Adults: A Systematic Review and Meta-Analysis

## TL;DR

This study reviews how nicotine in e-cigarettes affects young adults' heart health, finding short-term increases in blood pressure and heart rate.

## Contribution

The study systematically compares acute and chronic cardiovascular effects of nicotine-containing e-cigarettes in young adults versus conventional tobacco.

## Key findings

- Acute nicotine e-cigarette use increases systolic and diastolic blood pressure and heart rate in young adults.
- Chronic e-cigarette use is linked to reduced vasodilation and early signs of atherosclerosis.
- Nicotine-free e-cigarettes cause fewer cardiovascular effects compared to nicotine-containing ones.

## Abstract

Objective: To synthesize the current evidence on the cardiovascular effects of electronic cigarettes (ECs) in young adults (18–30 years), distinguishing between acute and chronic exposure, and comparing their effects to conventional tobacco (CT) use. Methods: A systematic review and meta-analysis (PROSPERO: CRD420251072847) was conducted following PRISMA guidelines. A total of 21 studies (12 RCTs, 8 case–control, 1 cohort) involving 17241 participants were included. Results: Acute EC use, particularly with nicotine, significantly increased systolic blood pressure (SBP: MD = 3.14 mmHg, 95% CI: 0.76 to 5.52), diastolic blood pressure (DBP: MD = 2.05 mmHg, 95% CI: 0.85 to 3.25), and heart rate (HR: MD = 4.23 bpm, 95% CI: 2.10 to 6.37), with effects most pronounced at 0 min post-exposure and dissipating within 1 h. Chronic EC use was associated with reduced endothelium-dependent vasodilation and early atherosclerotic changes. Nicotine-free ECs induced fewer cardiovascular alterations. Comparisons with CT revealed less severe cardiovascular damage with ECs, though still significant when compared to non-smokers. Conclusion: Nicotine-containing EC use in young individuals is associated with modest, predominantly acute and dose-dependent, cardiovascular effects, including transient increases in BP and HR. While initially less harmful than CT, the evidence is largely from cross-sectional studies and acute use, so ECs cannot be considered safe and their use warrants caution in youth.