What happens to your body when you quit smoking?

Key takeaways

• Within 20 minutes, heart rate and blood pressure drop (WHO).
• Within 12 hours, the carbon monoxide level in your blood drops to normal (WHO).
• After 1 year, coronary heart disease risk is about half that of a smoker (WHO).
• After 10 years, lung cancer risk falls to about half that of a smoker (WHO).
• Quitting helps at any age; the CDC says it can add as much as 10 years to life expectancy.

What happens in the first 20 minutes to 3 days?

Some changes begin almost immediately. The WHO says your heart rate and blood pressure drop within 20 minutes of quitting, and the carbon monoxide level in your blood drops to normal within 12 hours. The CDC adds that the nicotine level in your blood drops to zero within 24 hours.

Health agencies word the early milestones slightly differently. The NHS says the carbon monoxide in your blood is reduced by half after 8 hours and has dropped to that of a non-smoker by 48 hours, when your senses of taste and smell are also improving; the CDC's timeline places the carbon monoxide milestone at several days. By 72 hours, the NHS says breathing may feel easier because your bronchial tubes have started to relax.

• 20 minutes: heart rate and blood pressure drop (WHO).
• 8 hours: carbon monoxide in the blood is reduced by half (NHS).
• 12 hours: carbon monoxide level drops to normal (WHO).
• 24 hours: nicotine level in the blood drops to zero (CDC).
• 48 hours: taste and smell are improving (NHS).
• 72 hours: breathing may feel easier (NHS).

What changes in the first weeks and months?

Between 2 and 12 weeks after quitting, the WHO says your circulation improves and your lung function increases. Between 1 and 9 months, coughing and shortness of breath decrease. The NHS says lung function increases by up to 10% in the 3 to 9 months after quitting.

This is also when nicotine withdrawal fades. According to the National Cancer Institute, withdrawal symptoms are usually worst during the first week, peaking in the first 3 days, and their intensity usually drops over the first month.

How does your disease risk change over the years?

The longer-term benefits are about risk. According to the WHO, one year after quitting your risk of coronary heart disease is about half that of a smoker. Your stroke risk is reduced to that of a nonsmoker 5 to 15 years after quitting. At 10 years, your risk of lung cancer falls to about half that of a smoker, and your risk of cancers of the mouth, throat, esophagus, bladder, cervix, and pancreas decreases. At 15 years, your risk of coronary heart disease is that of a nonsmoker.

The CDC's timeline is similar: the risk of heart attack drops sharply 1 to 2 years after quitting, and by 20 years the risks of cancers of the mouth, throat, and voice box, and of pancreatic cancer, drop to close to those of someone who does not smoke.

• 1 year: coronary heart disease risk is about half a smoker's (WHO).
• 1 to 2 years: heart attack risk drops sharply (CDC).
• 5 to 15 years: stroke risk is reduced to a nonsmoker's (WHO).
• 10 years: lung cancer risk is about half a smoker's (WHO).
• 15 years: coronary heart disease risk is that of a nonsmoker (WHO).
• 20 years: mouth, throat, voice box, and pancreatic cancer risks are close to a nonsmoker's (CDC).

Is it still worth quitting if you've smoked for decades?

Yes. The CDC says quitting smoking is beneficial to health at any age and can add as much as 10 years to life expectancy. The WHO's estimates of life expectancy gained depend on the age at which you quit:

• Quitting at about 30: almost 10 years of life expectancy gained.
• Quitting at about 40: 9 years gained.
• Quitting at about 50: 6 years gained.
• Quitting at about 60: 3 years gained.