In normal doses (vaping, smoking), nicotine imitates part of the effects of a substance produced in the body (acetylcholine) and thereby activates nerve cells in the brain and the autonomic nervous system. The effect as a neurotoxin, i.e. blocking the function of nerve cells, only occurs in the event of a massive overdose, which is not achieved by inhalation. Highly potent neurotoxins are not available in pharmacies without a prescription. The addiction of smokers is due to a combined effect of nicotine with other components of tobacco smoke together with conditioned behavior, the “smoking ritual”. In the absence of tobacco smoke, the addictive potential of nicotine is very low, so that most vapers feel significantly less addictive pressure than smokers. In addition, smokers do not die because of their addiction but because of the harmful effects of the ingredients in tobacco smoke. In the cardiovascular system, nicotine, similar to caffeine, leads to a slight increase in blood pressure and heart rate. These effects are clinically harmless; the risk of serious illness (heart attack, stroke) or mortality is not increased by nicotine. However, people with severe cardiovascular diseases should avoid consuming nicotine.
Quoted from: KARL FRANZENS UNIVERSITY GRAZ INSTITUTE OF PHARMACEUTICAL SCIENCES - Pharmacology and Toxicology - Head: 0. Univ.-Prof. Dr. Bernhard Michael Mayer