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Nicotine is the main psychoactive substance in tobacco, which is most commonly smoked in cigarettes. Its effects include a feeling of relaxation and decreased tension and a brightened mood.

American statistics show that about 75% of people will try cigarettes. Of these, about 30% will become addicted to nicotine [ref].

How Nicotine Works

When smoked, nicotine is absorbed by the lungs and rapidly distributed into the blood stream, giving an almost immediate effect.

Nicotine binds to the nicotinic subtype of acetylcholine receptors in the brain, which accounts for its ability to improve one's attention, reaction time, learning and problem solving skills. It also activates the dopaminergic reward pathway, which produces feelings of contentment and also strongly reinforces its continued use. Nicotine increases the actions of various other neurotransmitters and brain hormones, including norepinephrine, vasopressin, beta-endorphin, ACTH and cortisol, all of which contribute to its stimulatory effects.

Nicotine Intoxication

Although in theory extremely high doses of nicotine could be lethal by causing respiratory depression, one would need to consume at one time the amount of nicotine contained in over 100 cigarettes, which is not realistic. At high but more usual doses, nicotine can can cause nausea, vomiting, abdominal pain, diarrhea, excess salivation, pallor, dizziness, headaches, increased blood pressure and heart rate, tremors, cold sweats, impaired concentration and confusion.

Effects of Long-Term Regular Nicotine Use

Nicotine is highly addictive and tends to give intense withdrawal symptoms that make it difficult for users to quick smoking. Long-term regular use is associated with significant health risks, many of which are due to inhaling the myriad of toxic substances other than nicotine that are found in tobacco smoke. Smoking significantly increases the risk of various severe and life-threatening conditions such as heart disease, strokes, chronic bronchitis, emphysema and COPD, and cancer of the lung, esophagus, bladder, pancreas, stomach, liver and kidney. Quitting smoking dramatically lowers the risks of these diseases back to more normal levels.

Nicotine Withdrawal

Withdrawal symptoms can emerge as quickly as a couple of hours after smoking the last cigarette, but more commonly begin about one or two days later, and can last for weeks or months. They include depressed moods, irritability, anxiety, insomnia, restlessness, difficulty concentrating, and increased appetite. Intense cravings for nicotine are usually present during this period.

Treating Nicotine Dependence

Helping people to quit smoking follows the same general principles that apply for treating all addictions, though in the case of nicotine dependence standard outpatient treatment is sufficient. In addition to the various psychotherapy or counseling modalities that can be tried, there are a few options for medications.

Nicotine replacement therapy involves replacing cigarettes with nicotine in the form of a patch, gum, lozenge, nasal spray or inhaler. For heavy smokers, nicotine replacement is started at the highest dosage and then tapered gradually over weeks or months. This treatment is quite effective on its own though results may be further improved by combining it with psychotherapy/ counseling [ref].

The antidepressants Bupropion and Nortriptyline have also been shown to help people quit smoking, and these effects seem to be independent from their antidepressant properties [ref]. Bupropion tends to have fewer general side-effects and would thus be a preferred choice.

Varenicline is a newer medication that has been shown to be quite effective for smoking cessation, perhaps even more so than Bupropion [ref].

Acupuncture has become an increasingly popular treatment for smoking cessation, though the scientific evidence remains inadequate to know whether or not it is effective [ref].

The question of how to decide which treatments to use first, or when to combine them, remains to be clarified.


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