Editor-In-Chief: C. Michael Gibson, M.S., M.D. ;Associate Editor(s)-in-Chief: Usama Talib, BSc, MD 
Smoking is a recreational activity in which a substance, most commonly tobacco, is burnt and the smoke tasted or inhaled. This is primarily done as a form of recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them available for absorption through the lungs. It can also be done as a part of religious rituals, to induce trances and spiritual enlightenment. The most common method of smoking today is through cigarettes, either industrially manufactured or rolled with loose tobacco and a rolling paper. Other forms, though less common, are pipes, cigars, bongs, and hookahs. Smoking is one of the most common forms of recreational drug use.
History of smoking can be dated to as early as 5000 BC. Tobacco first cultivated in the America in 3000 BC. Next important phase in smoking history returns to world exploration by sailors.
Smoking may be classified as heavy and non-heavy, depending on the number of cigarettes consumed per day. Smokers can also be classified with respect to duration as acute or chronic smokers.
Nicotine from the cigarette is rapidly absorbed form the lungs and diffuses readily into brain where it binds to nicotinic acetylcholine receptors. Stimulation of nicotinic acetyl choline receptor in the brain results in the release dopamine and other neurotransmitters which are responsible for the feeling of pleasure.
For details about the causes of smoking, view its risk factors.
Epidemiology and demographics
Tobacco use is the leading cause of preventable disease, disability, and death in the United States, accounting for more than 480,000 deaths every year, or 1 of every 5 deaths. In 2015, about 15 of every 100 U.S. adults aged 18 years or older (15.1%) currently smoked cigarettes, this means an estimated 36.5 million adults in the United States currently smoke cigarettes. It is more common among men than in women. Smoking is more common among adults aged 25-44. It is more common among non-Hispanic American Indians/Alaska Natives than other races.
The common risk factors for smoking are poor family ties, unemployment, alcohol addiction, using illicit drugs, anxiety disorders, and genetic susceptibility.
Screening for smoking is done on every visit to the physician by asking detailed questions related to smoking status and smoking history. The US Preventive Services Task Force guidelines recommend that clinicians ask all patients about tobacco use and provide tobacco cessation interventions for those who use tobacco.
Natural history, complications, and prognosis
Smoking may initially not cause any symptoms and is easy to give up. If not addressed smoking can lead to a vast variety of symptoms related to different organ systems. Smoking may cause carcinomas ultimately and lead to the death. Complications of smoking are not limited to a single organ system. Cardiovascular and respiratory systems are the most commonly involved. It increases the risk of coronary artery disease by 2 to 4 times. COPD is a common complication of smoking. Lung cancers are mostly attributed cigarette smoking. Cigarette smoking is the leading preventable cause of death in the United States. Smoking cessation has positive prognostic effect in lung cancer patients.
History and Symptoms
The primary method of diagnosing tobacco use is through the confidential interview or history. Symptoms of a chronic smokeer include fatigue, dyspnea on exertion, snoring and sleep apnea, retrosternal discomfort, heart burn, weight loss, breathlessness, sputum production and chest pain, leg pain, weight loss, loss of appetite and bloody sputum.
The physical examination of a patient who smokes may show tachycardia, hypertension, tachypnea, smoke-odored clothing, stained teeth or fingernails, hoarse voice and wheezing.
There are no diagnostic lab findings associated with smoking.
There are no chest x ray findings associated with smoking. Chest x ray can be used to diagnose various complications of smoking like carcinomas, pulmonary fibrosis, and COPD.
There are no ultrasound findings associated with smoking. Ultrasound can be used to diagnose various complications of smoking like carcinomas.
There are no CT scan findings associated with smoking. CT scan can be used to confirm various complications of smoking like carcinomas, pulmonary fibrosis, COPD and stroke.
There are no MRI findings associated with smoking. MRI can be used to confirm various complications of smoking like carcinomas, pulmonary fibrosis, COPD and stroke.
Other Imaging Studies
There are no additional imaging findings for smoking.
Other Diagnostic Studies
Breath carbon monoxide can be used to assess the presence of smoking in the last 24 hours.
Some general principles including the 5 As (ask, Assess, Advise, Assist and Arrange follow-up), non-pahramcological strategies like nicotine gum and nicotine patch and pharmacological strategies including bupropion, varenicline, inhalers and nasal sprays can be used to help quit smoking.
Surgical intervention is not recommended for the management of smoking. Various complications of smoking may benefit form surgery like carcinomas, stroke, coronary artery disease and ectopic pregnancy.
The primary prevention of smoking includes not selling cigarettes to individuals younger than 18, avoiding smoking near children, imposing taxes on cigarettes and campaigns to educate people regarding the risks and complications of smoking.
The secondary prevention of smoking is similar to its primary prevention.
- ↑ 1.0 1.1 "CDC - 2010 Surgeon General's Report - Consumer Booklet - Smoking & Tobacco Use".
- ↑ 2.0 2.1 "QuickStats: Number of Deaths from 10 Leading Causes — National Vital Statistics System, United States, 2010".
- ↑ 3.0 3.1 "CDC - 2014 Surgeon General's Report - Smoking & Tobacco Use".
- ↑ DOLL R, HILL AB (1950). "Smoking and carcinoma of the lung; preliminary report". Br Med J. 2 (4682): 739–48. PMC 2038856. PMID 14772469.
- ↑ Siu AL, U.S. Preventive Services Task Force (2015). "Behavioral and Pharmacotherapy Interventions for Tobacco Smoking Cessation in Adults, Including Pregnant Women: U.S. Preventive Services Task Force Recommendation Statement". Ann Intern Med. 163 (8): 622–34. doi:10.7326/M15-2023. PMID 26389730.
- ↑ 6.0 6.1 Parsons A, Daley A, Begh R, Aveyard P (2010). "Influence of smoking cessation after diagnosis of early stage lung cancer on prognosis: systematic review of observational studies with meta-analysis". BMJ. 340: b5569. doi:10.1136/bmj.b5569. PMC 2809841. PMID 20093278.
- ↑ Pearl R (1938). "TOBACCO SMOKING AND LONGEVITY". Science. 87 (2253): 216–7. doi:10.1126/science.87.2253.216. PMID 17813231.
- ↑ Iribarren C, Tekawa IS, Sidney S, Friedman GD (1999). "Effect of cigar smoking on the risk of cardiovascular disease, chronic obstructive pulmonary disease, and cancer in men". N Engl J Med. 340 (23): 1773–80. doi:10.1056/NEJM199906103402301. PMID 10362820.
- ↑ Boffetta P, Pershagen G, Jöckel KH, Forastiere F, Gaborieau V, Heinrich J; et al. (1999). "Cigar and pipe smoking and lung cancer risk: a multicenter study from Europe". J Natl Cancer Inst. 91 (8): 697–701. PMID 10218507.
- ↑ Henley SJ, Thun MJ, Chao A, Calle EE (2004). "Association between exclusive pipe smoking and mortality from cancer and other diseases". J Natl Cancer Inst. 96 (11): 853–61. PMID 15173269.
- ↑ "CDC - Fact Sheet - Current Cigarette Smoking Among Adults in the United States - Smoking & Tobacco Use".
- ↑ WYNDER EL, GRAHAM EA (1951). "Etiologic factors in bronchiogenic carcinoma with special reference to industrial exposures; report of eight hundred fifty-seven proved cases". AMA Arch Ind Hyg Occup Med. 4 (3): 221–35. PMID 14867935.
- ↑ Tingen MS, Andrews JO, Stevenson AW (2009). "Primary and secondary tobacco prevention in youth". Annu Rev Nurs Res. 27: 171–93. PMID 20192104 Check
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