Smoking Cessation Timeline: What Happens When You Quit

Reading time: 6 – 9 minutes

In the U.S., one-quarter of adults 18 years of age and older smoke cigarettes [1]. Smoking is truly a deadly habit. With about 4000 known chemicals in tobacco smoke, more than 50 of them are known to cause cancer. According to the World Health Organization, every six seconds someone in the world dies from tobacco use [2].

How’s this for bad odds: tobacco kills 50% of its regular users. One out of every two regular smokers will die from smoking [2].

cigarette-clock.jpgIn addition, an estimated 200,000 people die every year due to second-hand smoke exposure at work. The United States Environmental Protection Agency estimates that second-hand smoke is responsible for approximately 3000 lung cancer deaths annually among non-smokers [2]. Additionally, new research has linked second-hand smoke exposure to psychological problems in children, including attention deficit disorder (ADHD) and conduct disorder.

The best time to quit smoking is RIGHT NOW. And while quitting is tough, you can start counting the benefits of not smoking in as little as 20 minutes. Here’s what happens to your body when you quit smoking [3-5]:

Smoking cessation timeline – the health benefits over time

  • In 20 minutes, your blood pressure and pulse rate decrease, and the body temperature of your hands and feet increase.
  • Carbon monoxide in cigarette smoke reduces the blood’s ability to carry oxygen. At 8 hours, the carbon monoxide level in your blood decreases to normal. With the decrease in carbon monoxide, your blood oxygen level increases to normal.
  • At 24 hours, your risk of having a heart attack decreases.
  • At 48 hours, nerve endings start to regrow and the ability to smell and taste is enhanced.
  • Between 2 weeks and 3 months, your circulation improves, walking becomes easier and you don’t cough or wheeze as often. Phlegm production decreases. Within several months, you have significant improvement in lung function.
  • In 1 to 9 months, coughs, sinus congestion, fatigue and shortness of breath decrease as you continue to see significant improvement in lung function. Cilia, tiny hair-like structures that move mucus out of the lungs, regain normal function.
  • In 1 year, risk of coronary heart disease and heart attack is reduced to half that of a smoker.
  • Between 5 and 15 years after quitting, your risk of having a stroke returns to that of a non-smoker.
  • In 10 years, your risk of lung cancer drops. Additionally, your risk of cancer of the mouth, throat, esophagus, bladder, kidney and pancreas decrease. Even after a decade of not smoking however, your risk of lung cancer remains higher than in people who have never smoked. Your risk of ulcer also decreases.
  • In 15 years, your risk of coronary heart disease and heart attack in similar to that of people who have never smoked. The risk of death returns to nearly the level of a non-smoker.

Why is it so difficult to quit smoking?

In one word … nicotine.

Nicotine is an organic compound known as an alkoloid (meaning a nitrogen-containing ring compound, usually water-insoluble and alcohol soluble) found in the leaves of several species of plants, predominantly tobacco, as well as in lower quantities in several frequently consumed vegetables from the nightshade or Solanaceae family, including tomatoes, potatoes, aubergines (eggplant) and peppers [6]. Nicotine by itself is not carcinogenic [7]. However, it does inhibit UV-induced activation of cell death (a process known as apoptosis) [8], interfering with the body’s ability to destroy potentially cancerous cells.

Nicotine activates a specific type of neurotransmitter receptor – the acetylcholine receptor – an integral membrane protein widely distributed in the brain and neuromuscular junctions that normally responds to the binding of the neurotransmitter acetylcholine. This is nicotine’s addictive property: activation of acetylcholine receptors leads to an increased flow of adrenaline (epinephrine), which increases the heart rate, blood pressure, respiration and glucose levels in the blood.

When smokers try to cut back or quit smoking, they experience nicotine withdrawal. A regular smoker will have nicotine or its by-products present in their body for 3 to 4 days after quitting [9]. Withdrawal symptoms appear within a few hours and peak 24 to 48 hours after quitting [10]. Withdrawal symptoms include tobacco craving, a desire for sweets, increased coughing and impaired performance on tasks that require concentration [10-11]. Most symptoms last an average of one month, but hunger (due to the lack of increased blood glucose) and craving can last 6 months or more [10].

Did you ever smoke? How hard was it for you to quit? How did you do it?


  1. 2005 National Survey on Drug Use & Health Results. U.S. Department of Health and Human Services. Substance Abuse and Mental Health Services Administration. Office of Applied Studies. 2005.
  2. 10 Facts About Tobacco and Second-hand Smoke. World Health Organization.
  3. Quitting Smoking: Why To Quit and How To Get Help. National Cancer Institute.
  4. Quit Smoking – Smoking Cessation Support – Benefits. American Lung Association.
  5. When Smokers Quit – The Health Benefits Over Time. American Cancer Society. Revised 10/25/2006.
  6. Siegmund et al. Determination of the nicotine content of various edible nightshades (Solanaceae) and their products and estimation of the associated dietary nicotine intake. J Agric Food Chem. 1999 Aug;47(8):3113-20.
    View abstract
  7. Dasgupta and Chellappan. Nicotine-mediated cell proliferation and angiogenesis: new twists to an old story. Cell Cycle. 2006 Oct;5(20):2324-8. Epub 2006 Oct 16.
    View abstract
  8. Sugano et al. Nicotine inhibits UV-induced activation of the apoptotic pathway. Toxicol Lett. 2001 Dec 15;125(1-3):61-5.
    View abstract
  9. Guide to Quitting Smoking. American Cancer Society. Revised 10/27/2006.
  10. Hughes and Hatsumkami. The nicotine withdrawal syndrome: A brief review and update. International Journal of Smoking Cessation. 1992 1:21-26.
  11. Hughes, Higgins and Hatsukami. Effects of abstinence from tobacco: a critical review, in Research Advances in Alcohol and Drug Problems, vol 10. Edited by Kozlowski LT, Annis HM, Cappell HD, Glaser FB, Goodstadt MS, Israel Y, Kalant H, Sellers EM, Vingilis ER. New York, Plenum, 1990, pp 317-398.
About the Author

Walter Jessen, Ph.D. is a Data Scientist, Digital Biologist, and Knowledge Engineer. His primary focus is to build and support expert systems, including AI (artificial intelligence) and user-generated platforms, and to identify and develop methods to capture, organize, integrate, and make accessible company knowledge. His research interests include disease biology modeling and biomarker identification. He is also a Principal at Highlight Health Media, which publishes Highlight HEALTH, and lead writer at Highlight HEALTH.