MVIIIHealth The MVIII app
← Back

Research · Daily life

Smoking

Large cohorts link smoking to about three times the death rate of never smoking and more than a decade of lost life. Quitting is linked to lower risk at every age, and quitting before 40 avoided about 90% of the excess. Lung cancer risk falls with years since quitting but stays raised for decades. Quitters gained 4 to 5 kg.

Checked 2026-11-13
Status
A daily life factor, not a product. Cigarettes are regulated in the US by the FDA as tobacco products.
Also called
cigarette smoking, cigarettes, tobacco smoking, smoker, quitting smoking, smoking cessation, stop smoking, ex-smoker, former smoker, pack-years, light smoking, social smoking, cutting down
Studied for
living longer after quitting, heart health, lung health, breathing, cancer prevention, diabetes, mood, stress relief from smoking, weight control from smoking, light smoking being harmless

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help5

Reported risks6

What it was studied for, and what was found

Shown to help5

Strong

Death from any cause after quitting

Linked to fewer deaths after quitting at every age in large cohorts, with about 90% of the excess avoided by quitting before 40. A quit-program trial lowered deaths.

Compared with people who continued to smoke [1][2]; never-smokers, with ex-smokers' excess set against continuing smokers' excess [3]; people who continued to smoke, and never smokers [4]; never smokers, by years since quitting [5]; usual care, in a randomized trial of a quit program [6]

The numbers and sources
Effect
Adults who quit at ages 25 to 34, 35 to 44 or 45 to 54 gained about 10, 9 and 6 years of life against those who continued to smoke. Quitting before 40 lowered the death risk of continued smoking by about 90% [1]. In British doctors, stopping at 60, 50, 40 or 30 gained about 3, 6, 9 or 10 years [2]. Women who stopped at 25 to 34 or 35 to 44 had death rates 1.05 and 1.20 times those of never-smokers, 3% and 10% of the excess in continuing smokers [3]. Across four national cohorts, former smokers had a hazard ratio of 1.3 against never smokers. Quitting for under 3 years was linked to 90% to 95% less excess risk in people under 40, and quitting for 10 years or more to survival similar to never smokers [4]. In people 60 and older, former smokers' excess mortality (RM 1.34, 95% CI 1.28 to 1.40) fell with years since quitting, and gains were seen in people 80 and older [5]. In a randomized trial, a quit program raised 5-year quitting to 21.7% against 5.4% with usual care. Deaths were 8.83 against 10.38 per 1,000 person-years (HR for usual care 1.18, 95% CI 1.02 to 1.37) [6].
Population
202,248 US adults with 15,715 deaths [1]. 34,439 male British doctors followed 50 years [2]. 1.2 million UK women followed about 12 years [3]. 1.48 million adults in the US, UK, Norway and Canada with 122,697 deaths over 15 years [4]. 17 cohorts of people 60 and older in 7 countries [5]. 5,887 middle-aged smokers with mild airway obstruction, followed 14.5 years [6].
Sources
[1], [2], [3], [4], [5], [6]
Caveats
The cohorts are observational, and people who quit may differ in other ways from those who do not. Some people quit because they are already ill, which hides part of the gain in the first years. The trial's effect comes from a program that only a minority of its group used to quit, and it enrolled only people with airway obstruction [6].
Strong

Heart disease and stroke after quitting

Linked to lower heart disease and stroke risk within 5 years of quitting, with the excess falling steadily with time but staying above never smokers for 10 to 15 years.

Compared with never smokers, with former and current smokers each set against them [7]; patients with heart disease who continued to smoke [8]; people who continued to smoke, and never smokers [9]; people who continued to smoke [10]

The numbers and sources
Effect
In adults 60 and older, cardiovascular death had a hazard ratio of 2.07 (95% CI 1.82 to 2.36) in current smokers and 1.37 (95% CI 1.25 to 1.49) in former smokers against never smokers. The excess fell continuously with time since quitting. Heart attack and stroke followed the same pattern [7]. In people with coronary heart disease, quitting was linked to 36% lower death from any cause than continuing to smoke (RR 0.64, 95% CI 0.58 to 0.71) [8]. In heavy smokers, quitting within 5 years was linked to lower cardiovascular disease (HR 0.61, 95% CI 0.49 to 0.76) than continuing. Against never smokers, the excess stopped being significant 10 to 15 years after quitting (HR 1.25, 95% CI 0.98 to 1.60) [9]. In adults without diabetes, recent quitters (HR 0.47) and long-term quitters (HR 0.46, 95% CI 0.34 to 0.63) had fewer cardiovascular events than smokers [10].
Population
503,905 adults 60 and older in 25 cohorts, with 37,952 cardiovascular deaths [7]. 20 cohorts of patients with coronary heart disease [8]. 8,770 Framingham participants followed a median 26.4 years, 2,371 of them heavy smokers [9]. 3,251 Framingham Offspring participants followed a mean 25 years [10].
Sources
[7], [8], [9], [10]
Caveats
Observational. Many cohorts did not fully control confounding or check smoking status, though restricting to higher-quality studies changed little [8]. In people with diabetes, the estimates were similar but not significant [10].
Strong

Lung cancer after quitting

Linked to steadily lower lung cancer risk with each year after quitting in pooled cohorts, with about a fifth of the excess remaining 20 years on.

Compared with current smokers, as each review defined its reference [11][12]; people who continued to smoke, and never smokers [13]; never-smokers [3]; continuing smokers, by age at stopping [14]

The numbers and sources
Effect
The share of the reducible excess risk remaining was 81.4% 1 year after quitting, 57.2% at 5 years, 36.9% at 10, 26.7% at 15 and 19.7% at 20 [11]. Lung cancer death had an RR of 0.64 (95% CI 0.55 to 0.76) in people who had quit for under 10 years, 0.33 for 10 to 20 years and 0.16 for over 20 years, against 0.11 in never smokers [12]. Heavy former smokers had 39.1% lower lung cancer risk than continuing smokers within 5 years, yet a hazard ratio of 3.85 (95% CI 1.80 to 8.26) against never smokers after 25 years [13]. Women who stopped at 25 to 34 had a lung cancer death rate 1.84 times that of never-smokers [3]. For UK men who stopped at 60, 50, 40 or 30, the risk of dying of lung cancer by 75 was 10%, 6%, 3% and 2%, against 16% in continuing smokers [14].
Population
49 prospective cohorts in 20 countries [11]. 969,560 people in 24 studies [12]. 8,907 Framingham participants with 284 lung cancers over a median 28.7 years [13]. 1.2 million UK women [3]. 982 lung cancer cases and 3,185 controls in 1990, with UK national rates [14].
Sources
[11], [12], [13], [3], [14]
Caveats
Observational. People who quit after symptoms begin can make early quitters look worse, which is reverse causation. In heavy smokers, 4 in 10 lung cancers occurred more than 15 years after quitting [13].
Moderate

Lung function and COPD after quitting

Shown to slow the yearly loss of lung function to about half the rate of continued smoking, in a large trial of smokers with early airway obstruction.

Compared with people who continued to smoke [15][16]; usual care, in the randomized comparison [16]; never smokers, with current and former smokers each set against them [17]

The numbers and sources
Effect
People who quit gained an average 47 mL (2%) of FEV1 in the year after quitting. Their later decline was 31 mL a year against 62 mL in continuing smokers [15]. At 11 years, men who quit lost 30.2 mL a year and women 21.5 mL, against 66.1 mL and 54.2 mL in continuing smokers. FEV1 was under 60% of predicted in 38% of continuing smokers and 10% of sustained quitters. The intervention group as randomized lost less lung function than usual care [16]. In pooled studies, COPD risk against never smokers was 3.51 (95% CI 3.08 to 3.99) in current smokers and 2.35 (95% CI 2.11 to 2.63) in ex-smokers, and limited data showed it falling with longer quitting [17].
Population
3,926 smokers, mean age 48.5, with mild to moderate airway obstruction in 10 centers [15]. 77.4% of surviving participants at 11 years [16]. 133 studies of COPD [17].
Sources
[15], [16], [17]
Caveats
The comparison of quitters with continuing smokers is not randomized, since people chose whether to quit [15][16]. The pooled COPD estimates were markedly heterogeneous [17].
Moderate

Mood after quitting

Linked to small improvements in depression, anxiety and stress after quitting, in a Cochrane review of mostly cohort data rated very low to moderate in certainty.

Compared with people who continued to smoke [19]

The numbers and sources
Effect
Against continuing to smoke, quitting was linked to lower anxiety (SMD -0.28, 95% CI -0.43 to -0.13), depression (SMD -0.30, 95% CI -0.39 to -0.21), mixed anxiety and depression (SMD -0.31) and stress (SMD -0.19), and more positive affect (SMD 0.22). New mixed anxiety and depression was less common in quitters (OR 0.76, 95% CI 0.66 to 0.86). Results were similar in people with mental illness [19].
Population
102 studies with over 169,500 adults who smoked, followed at least 6 weeks [19].
Sources
[19]
Caveats
All studies were judged at serious risk of bias from confounding that changes over time, and there was some sign of publication bias [19]. People whose mood improves may find it easier to quit, which is reverse causation.

Mixed results1

Moderate

Type 2 diabetes after quitting

Mixed results: in pooled cohorts, diabetes risk was higher in the first 5 years after quitting than in current or never smokers, then fell with time.

Compared with never smokers [18]

The numbers and sources
Effect
Against never smokers, the RR of type 2 diabetes was 1.54 (95% CI 1.36 to 1.74) in people who had quit under 5 years before, 1.18 at 5 to 9 years and 1.11 (95% CI 1.02 to 1.20) at 10 years or more. Current smokers had an RR of 1.37 (95% CI 1.33 to 1.42) [18].
Population
88 prospective studies with 5,898,795 participants and 295,446 cases. 10 studies with 1,086,608 participants for time since quitting [18].
Sources
[18]
Caveats
Observational. Weight gain after quitting may explain the early rise. The review gives no direct comparison of recent quitters with people who kept smoking.

Amounts studied

Cohorts measured smoking as current, former or never, cigarettes a day, and pack-years. The heart disease review modeled 1, 5 and 20 cigarettes a day [20]. Heavy smoking was defined as 20 pack-years or more [9] or more than 21.3 pack-years [13].

Quitting was studied by age at quitting, in bands such as 25 to 34, 35 to 44 and 45 to 54 [1][3], and by years since quitting: under 3, 3 to 9 and 10 or more [4], under 5, 5 to 9 and 10 or more [18], and 1 to 20 years [11]. The quit-program trial gave a 10-week program of 12 group sessions, a physician message and nicotine gum [6].

Risks

Reported risks6

ModerateVery common

Weight gain after quitting

Shown to follow quitting, with a mean gain of 4 to 5 kg at 12 months in pooled trials, most of it in the first 3 months.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Untreated quitters gained a mean 1.12 kg at 1 month, 2.85 kg at 3 months, 4.23 kg at 6 months and 4.67 kg (95% CI 3.96 to 5.38) at 12 months. At 12 months an estimated 16% had lost weight, 37% gained under 5 kg, 34% gained 5 to 10 kg and 13% gained over 10 kg. Gains were similar with quit medicines [22]. In one cohort, recent quitters gained a median 2.7 kg over 4 years, and the weight gain did not change their lower cardiovascular risk [10].
Population
62 trials of quit treatments that recorded weight in people who stayed abstinent [22]. 3,251 Framingham Offspring participants [10].
Sources
[22], [10]
Caveats
The shares gaining each amount were calculated from pooled means and standard deviations, not counted directly [22].
StrongHow often is not known

Death from any cause in people who smoke

Linked to about two to three times the death rate of never smokers in large cohorts, and to more than a decade of lost life.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Current smokers aged 25 to 79 had about three times the death rate of never smokers (HR 3.0 in women, 2.8 in men), and lost more than 10 years of life expectancy [1]. Continuing smokers born 1900 to 1930 died about 10 years younger than lifelong non-smokers [2]. Women still smoking 3 years into follow-up had a death rate ratio of 2.97 (95% CI 2.88 to 3.07), and those smoking under 10 a day had 1.98 [3]. Current smokers had hazard ratios of 2.8 (women) and 2.7 (men) [4]. In people 60 and older, current smoking had an RM of 1.83 (95% CI 1.65 to 2.03) [5].
Population
202,248 US adults [1]. 34,439 British doctors [2]. 1.2 million UK women [3]. 1.48 million adults in 4 countries [4]. 17 cohorts of people 60 and older [5].
Sources
[1], [2], [3], [4], [5]
Caveats
Observational, with adjustment for age, education, alcohol and weight in the largest cohorts [1][4]. The rates are relative, so they give no single share of smokers who die of smoking.
StrongHow often is not known

Heart disease and stroke, even at one cigarette a day

Linked to more heart disease and stroke at every level of smoking. One cigarette a day carried about half the excess heart risk of 20 a day in men.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Against never smokers, men smoking 1 cigarette a day had an RR of coronary heart disease of 1.48 and those smoking 20 a day 2.04. In women the RRs were 1.57 and 2.84. One cigarette a day carried 46% of the excess coronary risk of 20 a day in men and 31% in women. For stroke, RRs were 1.25 and 1.64 in men, and 1.31 and 2.16 in women [20]. In adults 60 and older, current smokers had a cardiovascular death hazard ratio of 2.07, with risk rising with cigarettes smoked [7].
Population
141 cohort studies in 55 reports [20]. 503,905 adults 60 and older in 25 cohorts [7].
Sources
[20], [7]
Caveats
Observational. Adjusting for more confounders made the one-cigarette risk larger, not smaller [20].
StrongHow often is not known

Lung cancer and other cancers

Linked to about nine times the lung cancer risk of never smoking in pooled studies, and to raised risks of cancers of the larynx, throat, mouth and esophagus.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Current smokers had an RR of 8.96 (95% CI 6.73 to 12.11) for lung cancer, 6.98 for laryngeal, 6.76 for pharyngeal, 3.57 for upper digestive tract and 3.43 for oral cancer, against non-smokers [21]. In a second review, never smokers had an RR of lung cancer death of 0.11 (95% CI 0.07 to 0.15) against current smokers [12]. In UK women, the lung cancer death rate ratio for smokers was 21.4 [3].
Population
216 studies of 13 cancer sites, 1961 to 2003 [21]. 24 studies with 969,560 people [12]. 1.2 million UK women [3].
Sources
[21], [12], [3]
Caveats
The first review pooled case-control and cohort studies, and study type, sex and confounder adjustment changed the estimates [21].
ModerateHow often is not known

COPD, chronic bronchitis and emphysema

Linked to about three and a half times the COPD risk of never smoking in one meta-analysis, rising with amount smoked and pack-years.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Against never smokers, current smoking had an RR of 3.51 (95% CI 3.08 to 3.99) for COPD, 3.41 for chronic bronchitis and 4.87 (95% CI 2.83 to 8.41) for emphysema. Risk rose with amount smoked and pack-years [17].
Population
218 studies, 133 with COPD data, published to 2006 [17].
Sources
[17]
Caveats
Estimates were markedly heterogeneous and lower when based on lung function or when asthma was counted as COPD [17].
ModerateHow often is not known

Type 2 diabetes

Linked to 37% more type 2 diabetes in current smokers in one meta-analysis of 88 cohorts, rising with cigarettes smoked, and to more diabetes with secondhand smoke.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Current smoking had an RR of 1.37 (95% CI 1.33 to 1.42) against non-smoking. Light, moderate and heavy smokers had RRs of 1.21, 1.34 and 1.57. Never smokers exposed to secondhand smoke had an RR of 1.22 (95% CI 1.10 to 1.35) [18].
Population
88 prospective studies with 5,898,795 participants [18].
Sources
[18]
Caveats
Observational. The authors estimate attributable cases only on the assumption that the link is causal [18].

Claims tested and not found

  1. That a few cigarettes a day carry little heart risk. One cigarette a day carried 46% of the excess coronary risk of 20 a day in men and 31% in women [20].
  2. That quitting late in life brings no gain. In people 60 and older, the gains of quitting were seen in every age group, including people 80 and older [5]. British doctors who stopped at 60 gained about 3 years [2].
  3. That quitting harms mental health. Quitting was linked to small improvements in depression, anxiety and stress, including in people with mental illness [19].
  4. That weight gained after quitting cancels the heart gain. Quitters' lower cardiovascular risk barely changed after adjusting for weight gain [10].

Related

VapingNicotine pouchesBupropion

Sources

  1. Jha P, Ramasundarahettige C, Landsman V, et al. 21st-century hazards of smoking and benefits of cessation in the United States. New England Journal of Medicine. 2013. https://doi.org/10.1056/NEJMsa1211128
  2. Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years' observations on male British doctors. BMJ. 2004. https://doi.org/10.1136/bmj.38142.554479.AE
  3. Pirie K, Peto R, Reeves GK, et al. The 21st century hazards of smoking and benefits of stopping: a prospective study of one million women in the UK. The Lancet. 2013. https://doi.org/10.1016/S0140-6736(12)61720-6
  4. Cho ER, Brill IK, Gram IT, Brown PE, Jha P. Smoking Cessation and Short- and Longer-Term Mortality. NEJM Evidence. 2024. https://doi.org/10.1056/EVIDoa2300272
  5. Gellert C, Schöttker B, Brenner H. Smoking and all-cause mortality in older people: systematic review and meta-analysis. Archives of Internal Medicine. 2012. https://doi.org/10.1001/archinternmed.2012.1397
  6. Anthonisen NR, Skeans MA, Wise RA, et al. The effects of a smoking cessation intervention on 14.5-year mortality: a randomized clinical trial. Annals of Internal Medicine. 2005. https://doi.org/10.7326/0003-4819-142-4-200502150-00005
  7. Mons U, Müezzinler A, Gellert C, et al. Impact of smoking and smoking cessation on cardiovascular events and mortality among older adults: meta-analysis of individual participant data from prospective cohort studies of the CHANCES consortium. BMJ. 2015. https://doi.org/10.1136/bmj.h1551
  8. Critchley JA, Capewell S. Mortality risk reduction associated with smoking cessation in patients with coronary heart disease: a systematic review. JAMA. 2003. https://doi.org/10.1001/jama.290.1.86
  9. Duncan MS, Freiberg MS, Greevy RA, et al. Association of Smoking Cessation With Subsequent Risk of Cardiovascular Disease. JAMA. 2019. https://doi.org/10.1001/jama.2019.10298
  10. Clair C, Rigotti NA, Porneala B, et al. Association of smoking cessation and weight change with cardiovascular disease among adults with and without diabetes. JAMA. 2013. https://doi.org/10.1001/jama.2013.1644
  11. Reitsma M, Kendrick P, Anderson J, et al. Reexamining Rates of Decline in Lung Cancer Risk after Smoking Cessation. A Meta-analysis. Annals of the American Thoracic Society. 2020. https://doi.org/10.1513/AnnalsATS.201909-659OC
  12. Lai H, Liu Q, Ye Q, et al. Impact of smoking cessation duration on lung cancer mortality: A systematic review and meta-analysis. Critical Reviews in Oncology/Hematology. 2024. https://doi.org/10.1016/j.critrevonc.2024.104323
  13. Tindle HA, Stevenson Duncan M, Greevy RA, et al. Lifetime Smoking History and Risk of Lung Cancer: Results From the Framingham Heart Study. Journal of the National Cancer Institute. 2018. https://doi.org/10.1093/jnci/djy041
  14. Peto R, Darby S, Deo H, et al. Smoking, smoking cessation, and lung cancer in the UK since 1950: combination of national statistics with two case-control studies. BMJ. 2000. https://doi.org/10.1136/bmj.321.7257.323
  15. Scanlon PD, Connett JE, Waller LA, et al. Smoking cessation and lung function in mild-to-moderate chronic obstructive pulmonary disease. The Lung Health Study. American Journal of Respiratory and Critical Care Medicine. 2000. https://doi.org/10.1164/ajrccm.161.2.9901044
  16. Anthonisen NR, Connett JE, Murray RP. Smoking and lung function of Lung Health Study participants after 11 years. American Journal of Respiratory and Critical Care Medicine. 2002. https://doi.org/10.1164/rccm.2112096
  17. Forey BA, Thornton AJ, Lee PN. Systematic review with meta-analysis of the epidemiological evidence relating smoking to COPD, chronic bronchitis and emphysema. BMC Pulmonary Medicine. 2011. https://doi.org/10.1186/1471-2466-11-36
  18. Pan A, Wang Y, Talaei M, Hu FB, Wu T. Relation of active, passive, and quitting smoking with incident type 2 diabetes: a systematic review and meta-analysis. The Lancet Diabetes and Endocrinology. 2015. https://doi.org/10.1016/S2213-8587(15)00316-2
  19. Taylor GM, Lindson N, Farley A, et al. Smoking cessation for improving mental health. Cochrane Database of Systematic Reviews. 2021. https://doi.org/10.1002/14651858.CD013522.pub2
  20. Hackshaw A, Morris JK, Boniface S, Tang JL, Milenković D. Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports. BMJ. 2018. https://doi.org/10.1136/bmj.j5855
  21. Gandini S, Botteri E, Iodice S, et al. Tobacco smoking and cancer: a meta-analysis. International Journal of Cancer. 2008. https://doi.org/10.1002/ijc.23033
  22. Aubin HJ, Farley A, Lycett D, Lahmek P, Aveyard P. Weight gain in smokers after quitting cigarettes: meta-analysis. BMJ. 2012. https://doi.org/10.1136/bmj.e4439

Everything in the library