Nicotine, the active ingredient of tobacco, affects the brain, body and behaviour, including changing heart rate, intestinal action, endocrine functions, brain waves and general arousal. Nicotine effects centrally in the brain producing a mild high that induces craving.
Nicotine is highly addictive. It is both a stimulant and a sedative to the central nervous system. The ingestion of nicotine results in an almost immediate "kick" because it causes a discharge of epinephrine from the adrenal cortex. This stimulates the central nervous system, and other endocrine glands, which causes a sudden release of glucose. Stimulation is then followed by depression and fatigue, leading the abuser to seek more nicotine. Nicotine is absorbed readily from tobacco smoke in the lungs, and it does not matter whether the tobacco smoke is from cigarettes, cigars, or pipes.
The primary significance of nicotine in tobacco is to provide pharmacological effects, both acute (mood regulation, weight control) and long-term (reinforcing effects that create a continuing physiological need for nicotine). While nicotine in tobacco has both systemic pharmacological effects and acute sensory effects in the mouth, nose, and throat, the evidence in tobacco industry documents demonstrates that the acute sensory effects of nicotine are secondary in importance to the pharmacological effects of nicotine that underlie consumer satisfaction. Whilst smoking fulfils a psychological need in certain individuals it is only the inhaling cigarette smoker who is likely to gain psychopharmacological satisfaction from nicotine and become dependent on it.
The tobacco industry distinguishes the role of nicotine from flavorants. A book on flavoring tobacco lists approximately a thousand flavorants, but fails to list nicotine as a flavoring agent. In fact, nicotine's flavor is unpleasant, and the tobacco industry has gone to significant lengths to mask the flavor of increased levels of nicotine in cigarettes.
There is evidence that some of the sensory effects associated with nicotine, e.g., "irritation and impact," are sought by smokers at least in part because these effects are always followed by the pharmacological effects they seek. Thus, smokers learn to associate the sensory impact of nicotine (burning in the throat) with the resulting psychoactive effects of nicotine, and thus look for these sensory signals in tobacco products. This is known as secondary reinforcement.
The tobacco industry's development of nicotine analogues also demonstrates the industry's interest is in nicotine's pharmacological effects on the central nervous system, rather than in its sensory effects. The focus of industry research has been to develop compounds that will duplicate the pharmacological effects of nicotine on the central nervous system. Nowhere in the referenced tobacco industry documents concerning nicotine analogues is there mention of concern to duplicate any flavor, taste, or other acute sensory effects that may be associated with nicotine.
Reduction in heavy or prolonged nicotine use can produce some of the following withdrawal effects; sweating or rapid pulse, increased hand tremor, insomnia, nausea or vomiting, physical agitation, anxiety, transient visual, tactile, or auditory hallucinations or illusions, and grand mal seizures.
A study by researchers at San Francisco General Hospital found that African Americans take in 30% more nicotine with every cigarette as compared with White or Hispanic Americans. Researchers also found that African Americans metabolize cotinine, a nicotine byproduct, more slowly.
Nicotine is highly addictive, and American tobacco companies are believed to manipulate the amount of nicotine in cigarettes to maintain customers' addictions. If it can be shown that people buy cigarettes in order to satisfy an addiction, then cigarette sales should have to meet the regulations for selling drugs. This could prevent the sale of cigarettes in the USA, on the grounds that they are unsafe products.
Cigarettes are relentlessly advertised with highly effective overt and subliminal messages that smoking is good.