How nicotine works

Nicotine causes chemical or biological changes in the brain. This effect is called psychoactive and although it is less dramatic than heroin or cocaine, the strength of the addiction is just as powerful. It is a 'reinforcing' drug, which means that users desire the drug regardless of the damaging effects. For example, in research conducted in 1994, only 50% of smokers who suffered a heart attack managed to quit smoking even though their doctors advised them to. Coincidentally, 50% of all regular smokers die as a result of smoking. ⁴

Nicotine addiction is a physical dependency. Withdrawal symptoms are severe and most smokers cannot quit on their first attempt because of these symptoms. The human body builds a tolerance to nicotine and the effect of the drug is reduced over time. As a result, regular smokers can inhale greater amounts of smoke and therefore greater amounts of toxins, without showing immediate effects (ie coughing, nausea). Nicotine is extremely poisonous if consumed in large amounts and most people feel sick and dizzy the first time they smoke. These negative affects are quickly overcome. ⁵ Over time the body builds a tolerance to nicotine, resulting in an increase in the amount of cigarettes smoked. ¹

Nicotine in the body

Cigarette smoke is acidic and therefore nicotine is absorbed through the lungs. Pipe and cigar smoke is alkaline and the nicotine is absorbed through the mouth. Human lungs are very efficient in absorbing nicotine which then moves through the bloodstream and into the brain and other organs of the body. ¹ It takes only 10 seconds for nicotine to reach the brain after being inhaled. This causes several physiological reactions ^1,2

• Acute increase in heart rate and blood pressure
• Constriction of blood vessels causing a temperature
• drop in the hands and feet
• Brain waves are altered and muscles relax.

Levels of dependency

Levels of dependency vary, but 89% of smokers have a cigarette every one to two hours throughout the day. ⁸ A highly addicted smoker smokes more than 25 cigarettes a day, ranks the first cigarette in the day as the most important, and will smoke within 30 minutes of waking up. ²

Withdrawal symptoms

The most severe withdrawal symptoms occur within the first week although the craving for cigarettes usually persists for months and even years.5 The desire to smoke tends to be especially strong when a person is under stress. The typical withdrawal symptoms are: ¹

• headaches
• anxiety and irritability
• difficulty concentrating and sleeping hunger
• decreased heart rate and blood pressure
• craving for nicotine.

Other side-effects, such as tiredness and coughing, are indications that the body is in a state of repair and is cleaning out the poisons associated with smoking. According to the U.S. Lung Health Study, weight gain for men averaged 4.9 kg and 5.2 kg. for women 7 in the first year after quitting.

Quitting smoking

There are now more former smokers (26%), over the age of 15, than current smokers (25%). ⁹ The most common reason given for quitting smoking is concern about future personal health. Other reasons for quitting were life-style changes, cost of cigarettes, having a baby, and smoke-related illness or death of a friend or family member. The most common reason current smokers give for not quitting is lack of will-power.

There are five successive stages to quitting smoking:

• Pre-contemplation -- not thinking about quitting
• Contemplation -- thinking about quitting but not yet ready
• Preparation -- getting ready to quit
• Action -- quitting
• Maintenance -- remaining a non-smoker.

References

1. US Department of Health and Human Services. The Health Consequences Of Smoking: Nicotine Addiction. A report Of The Surgeon General. Rockville, Maryland: Public Health Service, Centers for Disease Control, Center for Health Promotion and Education, Office in Smoking and Health, 1988.
2. Zevin S, Gourlay SG, Benowitz NL. Clinical Pharmacology Of Nicotine. Clinics in Dermatology. 1998;16: 557-564.
3. Lynch B, Bonnie R (Eds). Growing Up Tobacco Free; Preventing Nicotine Addiction In Children And Youth. Committee on Preventing Nicotine Addiction in Children and Youth, Division of Biobehavioural Sciences and Mental Disorders, Institute of Medicine, National Academy Press, Washington DC, 1994.
4. Doll R, Peto R, Wheatley K, Gray R, Sutherland I. Mortality In Relation To Smoking: 40 Years' Observations On Male British Doctors. British Medical Journal. 1994;309:901-11.
5. Schiffman S. Tobacco "Chippers" - Individual Differences In Tobacco Dependence. Psychopharmacology. 1989;97:539-537.
6. Benowitz NL. Pharmacologic Aspects Of Cigarette Smoking And Nicotine Addiction. New England Journal of Medicine. 1988;319:1318 -1330.
7. O'Hara P, Connett J.E. Lee WW, Nides M, Murray R, Wise R. Early And Late Weight Gain Following Smoking Cessation In The Lung Health Study. American Journal of Epidemiology. 1998;148(9): 821-830.
8. Ellison LF, Morrison HI, de Groh M, Villenueve PJ. Health Consequences Of Smoking Among Canadian Smokers: An Update. Chronic Diseases in Canada. 1999; 20(1).
9. Health Canada. Government Tobacco Control Interventions. CTUMS (Canadian Tobacco Use Monitoring Survey), Wave 1, February-June 1999.

(© Health Canada, 2002)

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