Nicotine: health effects

Here is what experts consider to be the current evidence regarding the health effects of nicotine. The main message is that nicotine is addictive, but poses few direct health risks when separated from tobacco smoke. People who do not already smoke should not use nicotine.

Addiction is the Main Risk: Nicotine is the chemical in tobacco that causes addiction (dependence) by triggering pleasure and making people want to avoid withdrawal symptoms (cravings).
Tobacco Smoke is the Danger: The thousands of toxic and cancer-causing chemicals in tobacco smoke—not the nicotine—are what make smoking lethal.
Aids to Quitting Smoking: Nicotine-containing products like Nicotine Replacement Therapy (NRT: patches, gum) and vapes (e-cigarettes) are effective tools to help people quit smoking by managing cravings without the severe harm of tobacco.
- Vaping is recommended as a quit aid and is considered significantly less harmful than smoking.
- Evidence shows people using nicotine vapes are almost twice as likely to quit successfully compared to those using NRT.
Who Should Use Nicotine: Nicotine products are primarily for people who already smoke and are trying to quit. They should not be used by non-smokers.

Specific Health Impacts of Nicotine (Separate from Smoking)

The evidence suggests that many of the severe health problems linked to smoking are not caused by nicotine alone:

Heart Health: Nicotine can cause a temporary, short-term rise in heart rate and blood pressure. However, long-term evidence of harm is lacking. Smokers who completely switch to vapes or NRT often see significant and early improvements in their vascular health.
Cancer: The research consensus is that nicotine does not cause cancer.
Brain Development: There is limited evidence that nicotine significantly impacts cognitive function in humans, and separating its effects from smoking is difficult. Pre-existing factors may also play a role.
Mental Health: While smoking is linked to conditions like depression, nicotine itself does not appear to be the main driver; other chemicals in tobacco smoke play a larger role.
Toxicity: At very high levels, nicotine can cause acute side effects like nausea and dizziness, but users quickly learn to avoid these toxic doses.

Reference: ASH. Evidence summary: The health effects of nicotine. November 2025. ASH-evidence-brief-on-nicotine-V6-Nov25.pdf