The effects of smoking cigarettes on human health are far reaching and profound. The United States Surgeon General advises that smoking cigarettes causes lung disease, cancer, heart disease, type 2 diabetes, immune diseases, vision problems, periodontal disease, infertility, osteoporosis, and skin problems.1,2
Lung Health
It is well established that smoking cigarettes damages the lungs. Smoking not only affects the functioning of the lungs, but it also increases the risk of developing pulmonary conditions such as COPD and chronic bronchitis.1,2
A 2022 observational study quantified the effect of smoking on lung function as assessed by forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFr), and functional performance via the 6-minute walk test (6MWT).3 The study involved 130 smoking university students and compared to a predicted normal as calculated using previously established guidelines. Compared to the predicted normal values, the mean value of FVC was 0.3 liters lower, FEV1 was 0.13 liters lower, PEFr was 21.97 liters/minute lower, and 6MWT was 79.76 meters less (p<0.05 for all).
A 2016 analysis of the Rotterdam Study, a prospective population-based cohort study, found that among current smokers (n=3,078), the incidence of COPD was 26.0% (19.7 per 1,000 person-years) compared to 13.6% for former smokers (8.3 per 1,000 person-years, n=6,091) and 6.4% for never smokers (4.1 per 1,000 person-years, n=4,997).4
A 1995 prospective cohort study of 74,072 women found that cases of asthma and bronchitis were higher among smokers.5 Over ten years of follow-up, chronic bronchitis diagnosis was higher in current smokers (2.1 per 1,000 person-years) than former smokers (0.88 per 1,000 person-years) and never smokers (0.79 per 1,000 person-years).
Cancer Risk
The World Health Organization’s International Agency for Research on Cancer (IARC) has identified 62 carcinogens in tobacco smoke.6,7 Cancers that have been identified as occurring more often in cigarette smokers than nonsmokers include lung, lower urinary tract, renal-cell, upper aerodigestive tract, pancreatic, stomach, colorectal, liver, breast, cervical, endometrial, prostate, leukemia, and other organs (salivary gland, small intestine, gallbladder, extra-hepatic bile ducts, soft-tissue sarcoma, skin, ovarian, testicular, central nervous system, thyroid, adrenal, lymphoma, and multiple myeloma). Smoking is strongly associated with oral squamous cell carcinoma, especially in women.8,9
Heart Disease
A 1987 prospective cohort study of 119,404 nurses sought to quantify the incidence of coronary heart disease (CHD) in relation to cigarette smoking over six years of follow-up.10 The incidence of fatal CHD increased with higher cigarette use, with a 5 per 100,000 person-years incidence among nonsmokers, 6 among ex-smokers (adjusted Relative Risk [RR] 1.2), 8 for those who smoked 1-14 cigarettes per day (RR 1.9), 19 for 15-25 cigarettes per day (RR 4.3), and 27 for ≥25 cigarettes per day (RR 5.4). Similarly, the rate of nonfatal myocardial infarction (MI) increased with cigarette use, with 16 per 100,000 person-years incidence among nonsmokers, 25 among ex-smokers (RR 1.5), 37 for 1-14 cigarettes per day (RR 2.5), 69 for 15-24 cigarettes per day (RR 4.7), and 92 for ≥25 cigarettes per day (RR 6.3).
Diabetes
Several large prospective cohort studies have established the link between smoking cigarettes and type 2 diabetes risk.11-13 An analysis of data from the Cancer Prevention Study I, a prospective cohort study conducted from 1959-1972, found a dose-response relationship between rates of diabetes and cigarette smoking (n=709,827).13 Among those who smoked ≥2 packs per day at baseline, the incidence rate of diabetes mellitus was 5.5 per 1,000 person-years compared to 4.3 per 1,000 person-years for never smokers (adjusted incidence rate ratio [IRR] 1.45). For women, the incidence of diabetes mellitus was 4.3 per 1,000 person-years for ≥2 packs per day smokers compared to 3.9 per 1,000 person-years for never smokers (IRR 1.74).
Immune System
Smoking cigarettes has been linked to increased incidence of infection, especially lung infections, as well as increased inflammatory markers.14 A 1983 study randomized 64 smokers to either continue or to cease smoking cigarettes for three months.15 Compared to baseline, there was a significant decrease in lymphocyte counts (3.3 to 2.7, p<0.005) and increase in immunoglobulin IgG (8.38 to 9.10, p<0.05) and IgM (1.64 to 1.91, p<0.01) among those who quit smoking. Natural killer (NK) cell activity also increased among those who quit smoking, as measured by release of NK cells on melanoma cells (effector target cell ratio 15.67 vs 10.86 for smokers, p<0.01) and Chang cells (effector target cell ratio 12.1 vs 9.1, p<0.005). There were marginal or no changes in NK activity and immunoglobulin levels in smokers.
A 2000 population-based case-control study examined the relationship between smoking and pneumococcal infections.16 Among current smokers, 28.7% had pneumococcal infections (OR 5.4) compared to 20.3% of those exposed to second-hand smoke (OR 2.5), 11.9% of former smokers (OR 1.2), and 10.9% of never smokers. Incidence increased with heavier cigarette use, with 55.2% incidence among those who smoked 1-14 cigarettes per day (adjusted OR 2.3, p=0.006), 68.3% for 15-24 cigarettes per day (OR 3.7, p<0.001), and 74% for ≥25 cigarettes per day (OR 5.5, p<0.001).
Vision
Smoking cigarettes has been associated with a variety of ocular disorders, including age-related macular degeneration, cataracts, thyroid ophthalmopathy, and strabismus in the offspring of smoking mothers.17
Effects on Skin
Cigarette smoking affects human skin in numerous ways. One of the more prominent changes is premature skin aging, including the accelerated development of wrinkles.18,19 A 2001 study of 407 Korean men and women assessed the severity of wrinkles using photographic scales.20 The presence of severe wrinkles (adjusted for age and sex) was higher among those who smoked more, with 40.7% of participants who smoked <1 pack per year having severe wrinkles compared to 79.6% for ≥50 packs per year (Odds Ratio [OR] 5.53, 95% Confidence Interval [CI] [1.96-15.60], p=0.002).
Smoking is also associated with an increased risk of developing psoriasis. A 2007 prospective cohort study with nested case-control analysis examined the incidence of psoriasis.21 Among smokers (n=3,021), 33.5% had psoriasis compared to 27.0% of nonsmokers (n=6,956) (adjusted OR 1.45, 95% CI [1.16-1.59]).
Effects on Hair
Smoking has been associated with androgenetic alopecia in men. A 2007 study of 740 Taiwanese men found that smokers were significantly more likely to have moderate to severe androgenetic alopecia (27.1% vs 17.8%, adjusted OR 1.77, 95% CI [1.14-2.760, p=0.01).22
Second-Hand Smoke
Smoking cigarettes harms others who are exposed to second-hand smoke. The Centers for Disease Control and Prevention (CDC) estimates that second-hand smoke exposure accounts for over 40,000 preventable deaths per year among adults who don’t smoke, in addition to 400 infants.1,2 Secondhand smoke can cause coronary heart disease, stroke, and lung cancer. In children, secondhand smoke exposure is associated with respiratory infections, ear infections, asthma, and sudden infant death syndrome.
Exposure Levels
Current evidence indicates that there is no risk-free level of exposure to cigarette smoke.1,2,6,7 While the duration and level of exposure to cigarette smoke is directly correlated with risks of adverse health outcomes, even low levels of exposure as with second-hand smoke exposure increase health risks.
Electronic Cigarettes
The long-term health effects of the use of electronic cigarettes, or e-cigarettes, remain understudied as of this writing in 2025. Emerging evidence suggests that some of the harms of smoking cigarettes can be reduced in current smokers who switch to e-cigarettes; however, the quality of the evidence is not strong, and no consensus recommendations exist regarding use of e-cigarettes as an option for decreasing risks associated with cigarette use.
A 2014 systematic review of 76 studies of the health effects of electronic cigarettes found that no firm conclusions can be drawn on the safety of electronic cigarettes.23 Studies were critiqued for methodologic shortcomings and the fact that one third of authors had conflicts of interest. A 2022 systematic review included 93 articles and concluded that the strength of the evidence had improved only slightly with either nonsignificant or mixed results for all outcomes when comparing e-cigarette users to nonsmokers.24 A major shortcoming of the literature was the lack of studies on exclusive e-cigarette users.
In individuals who initiate tobacco use with e-cigarettes who have never smoked cigarettes effects include increased heart rate, mean arterial pressure, and oxidative stress, as well as alterations of respiratory epithelial cells and increased airflow resistance.25 All of these physiologic changes are associated with acute cardiovascular events such as heart attack and stroke. All expert bodies strongly recommend against initiation of e-cigarette use in current nonsmokers.
References
- The Health Consequences of Smoking: 50 Years of Progress. A Report of the Surgeon General. 2014. https://www.ncbi.nlm.nih.gov/books/NBK179276/pdf/Bookshelf_NBK179276.pdf
- A Report of the Surgeon General. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease. 2014. https://www.ncbi.nlm.nih.gov/books/NBK53017/
- Mohamed Abdelaal AA, Mohamed Mousa GS. Impact of Cigarettes Smoking on Undergraduates' Lung Health and Functional Performance: Observational Cross-Sectional Study. Int J Prev Med. 2022;13:59. doi:10.4103/ijpvm.IJPVM_308_20
- Terzikhan N, Verhamme KM, Hofman A, Stricker BH, Brusselle GG, Lahousse L. Prevalence and incidence of COPD in smokers and non-smokers: the Rotterdam Study. Eur J Epidemiol. Aug 2016;31(8):785-92. doi:10.1007/s10654-016-0132-z
- Troisi RJ, Speizer FE, Rosner B, Trichopoulos D, Willett WC. Cigarette smoking and incidence of chronic bronchitis and asthma in women. Chest. Dec 1995;108(6):1557-61. doi:10.1378/chest.108.6.1557
- IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 83: Tobacco Smoke and Involuntary Smoking. Lyon, France: World Health Organization; 2004.
- IARC monographs on the evaluation of carcinogenic risks to humans Volume 100E: Personal Habits and Indoor Combustions. Lyon, France: World Health Organization; 2012. p. 319-332.
- Muscat JE, Richie JP, Jr., Thompson S, Wynder EL. Gender differences in smoking and risk for oral cancer. Cancer Res. Nov 15 1996;56(22):5192-7.
- Takezaki T, Hirose K, Inoue M, et al. Tobacco, alcohol and dietary factors associated with the risk of oral cancer among Japanese. Jpn J Cancer Res. Jun 1996;87(6):555-62. doi:10.1111/j.1349-7006.1996.tb00259.x
- Willett WC, Green A, Stampfer MJ, et al. Relative and absolute excess risks of coronary heart disease among women who smoke cigarettes. N Engl J Med. Nov 19 1987;317(21):1303-9. doi:10.1056/nejm198711193172102
- Rimm EB, Chan J, Stampfer MJ, Colditz GA, Willett WC. Prospective study of cigarette smoking, alcohol use, and the risk of diabetes in men. BMJ (Clinical research ed). Mar 4 1995;310(6979):555-9. doi:10.1136/bmj.310.6979.555
- Manson JE, Ajani UA, Liu S, Nathan DM, Hennekens CH. A prospective study of cigarette smoking and the incidence of diabetes mellitus among US male physicians. Am J Med. Nov 2000;109(7):538-42. doi:10.1016/s0002-9343(00)00568-4
- Will JC, Galuska DA, Ford ES, Mokdad A, Calle EE. Cigarette smoking and diabetes mellitus: evidence of a positive association from a large prospective cohort study. Int J Epidemiol. Jun 2001;30(3):540-6. doi:10.1093/ije/30.3.540
- Arnson Y, Shoenfeld Y, Amital H. Effects of tobacco smoke on immunity, inflammation and autoimmunity. J Autoimmun. May 2010;34(3):J258-65. doi:10.1016/j.jaut.2009.12.003
- Hersey P, Prendergast D, Edwards A. Effects of cigarette smoking on the immune system. Follow-up studies in normal subjects after cessation of smoking. Med J Aust. Oct 29 1983;2(9):425-9.
- Nuorti JP, Butler JC, Farley MM, et al. Cigarette smoking and invasive pneumococcal disease. Active Bacterial Core Surveillance Team. N Engl J Med. Mar 9 2000;342(10):681-9. doi:10.1056/nejm200003093421002
- Solberg Y, Rosner M, Belkin M. The association between cigarette smoking and ocular diseases. Surv Ophthalmol. May-Jun 1998;42(6):535-47. doi:10.1016/s0039-6257(98)00002-2
- Just M, Ribera M, Monsó E, Lorenzo JC, Ferrándiz C. Effect of smoking on skin elastic fibres: morphometric and immunohistochemical analysis. Br J Dermatol. Jan 2007;156(1):85-91. doi:10.1111/j.1365-2133.2006.07575.x
- Yin L, Morita A, Tsuji T. Alterations of extracellular matrix induced by tobacco smoke extract. Arch Dermatol Res. Apr 2000;292(4):188-94. doi:10.1007/s004030050476
- Chung JH, Lee SH, Youn CS, et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Archives of dermatology. Aug 2001;137(8):1043-51.
- Huerta C, Rivero E, Rodríguez LA. Incidence and risk factors for psoriasis in the general population. Archives of dermatology. Dec 2007;143(12):1559-65. doi:10.1001/archderm.143.12.1559
- Su LH, Chen TH. Association of androgenetic alopecia with smoking and its prevalence among Asian men: a community-based survey. Archives of dermatology. Nov 2007;143(11):1401-6. doi:10.1001/archderm.143.11.1401
- Pisinger C, Døssing M. A systematic review of health effects of electronic cigarettes. Prev Med. Dec 2014;69:248-60. doi:10.1016/j.ypmed.2014.10.009
- Wasfi RA, Bang F, de Groh M, et al. Chronic health effects associated with electronic cigarette use: A systematic review. Front Public Health. 2022;10:959622. doi:10.3389/fpubh.2022.959622
- Izquierdo-Condoy JS, Naranjo-Lara P, Morales-Lapo E, et al. Direct health implications of e-cigarette use: a systematic scoping review with evidence assessment. Front Public Health. 2024;12:1427752. doi:10.3389/fpubh.2024.1427752
