Heart risk starts falling soon after you quit smoking, and the drop in the first five years is large. In a long-running US study, heavy smokers who quit had about 39% lower risk of cardiovascular disease within five years than those who kept smoking.1
Getting all the way back to the risk of someone who never smoked takes longer: roughly 10 to 15 years in that study, and longer still for heavy smokers in others. So quitting pays off quickly, and a past smoking history still belongs in your risk picture for years.
Key takeaways
- Most of the early benefit of quitting arrives within about five years.
- Some extra risk lingers for a decade or more, and longest for the leg arteries.
- How much you smoked in total shapes how long the leftover risk lasts.
- Weight gain after quitting did not cancel the heart benefit in large US cohorts.
- Two screening tests have rules written specifically around smoking history.
How fast heart risk falls after quitting
The best US evidence comes from the Framingham Heart Study, which tracked 8,770 people for a median of 26 years and updated their smoking status along the way. The main analysis looked at heavy smokers, defined as 20 pack-years or more.
Compared with people who kept smoking, those who had quit within the past five years had a clearly lower rate of heart attack, stroke, heart failure and cardiovascular death. The rate fell from about 11.6 to about 6.9 events per 1,000 people per year.
What remains, and for how long
The same study asked a second question: when does an ex-smoker look like someone who never smoked? For heavy smokers, the answer was not five years. Former smokers no longer had significantly higher risk than never smokers somewhere between 10 and 15 years after quitting.1
Other cohorts suggest the tail can be longer, and that it differs by artery.
| Study | What it followed | What it found |
|---|---|---|
| Framingham (US) | Heavy smokers, heart and stroke events | Lower risk within 5 years of quitting; near never-smoker levels at 10 to 15 years |
| ARIC (US) | 13,355 adults over 26 years | Raised risk lasted up to 20 years for coronary heart disease and up to 30 years for leg artery disease |
| Korean national cohort | 5.4 million adults | Light ex-smokers matched never smokers within 10 years; heavier ex-smokers needed more than 25 |
In the ARIC study, a longer time since quitting was consistently tied to lower risk of all three conditions studied, but significantly raised risk persisted for up to 30 years for peripheral artery disease and up to 20 years for coronary heart disease.2 Peripheral artery disease is plaque in the arteries of the legs.
These studies differ in who they enrolled and how they measured smoking, so the exact year counts should be read as ranges. The direction is the same in all three: risk keeps falling the longer you stay quit.
How much you smoked matters
Doctors measure lifetime smoking in pack-years: packs per day multiplied by years smoked. One pack a day for 20 years is 20 pack-years. So is two packs a day for 10 years.
The Korean study, which included more than 5 million adults, split ex-smokers by this number. Those with fewer than 8 pack-years had cardiovascular risk similar to never smokers within 10 years of quitting. Ex-smokers with 8 pack-years or more showed a slower decline and needed more than 25 years for the leftover risk to disappear.3
If you do not know your pack-years, work them out once and write the number down with the year you quit. Both figures are useful to any doctor estimating your risk.
Weight gain after quitting
Many people gain weight when they stop smoking, and some worry that the gain undoes the benefit. Three large US cohort studies looked at exactly this.
Recent quitters did have a temporarily higher risk of type 2 diabetes, which peaked five to seven years after quitting and then declined. The rise tracked with weight gain and was not seen in quitters who did not gain.
The heart result was reassuring. Quitters had lower rates of death from cardiovascular disease than continuing smokers at every level of weight gain, and people more than six years past quitting had about half the rate.4 Blood sugar is worth watching in the first years after you stop. Our guide to prediabetes and heart risk explains why.
Why calculators can miss a past habit
A risk calculator may not reflect an old habit. The Framingham authors noted that risk calculators treat former smokers as at risk for only five years, while their data showed risk staying above never-smoker levels past that point.
That does not make your calculated number wrong. It means a heavy smoking history is context your doctor should weigh next to it. Our guide to the PREVENT risk calculator covers what the estimate includes and leaves out.
Screening for ex-smokers
Routine risk checks are the same for everyone: blood pressure, cholesterol and blood sugar. Two further screening tests have rules written around smoking history. Neither is a heart test, but both come up in the same conversation.
- Abdominal aortic aneurysm. The US Preventive Services Task Force recommends a one-time ultrasound for men aged 65 to 75 who have ever smoked.5 For women in that age range who have smoked, it found the evidence insufficient to judge.
- Lung cancer. The Task Force recommends a yearly low-dose CT scan for adults aged 50 to 80 with at least a 20 pack-year history who still smoke or quit within the past 15 years.6
On the heart side, smoking is a major risk factor for plaque in the arteries, so some ex-smokers and their clinicians decide to look for it directly.
Your next step
If you smoked for years and want to know where your arteries stand, read our guide to the coronary calcium score, a scan that measures calcified plaque in the heart arteries, and our guide to the ApoB test.
You can also answer the three quick questions in the screener on the Cardio Res-Q program page. Tobacco history is one of the risk factors the program lists.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
Is it too late to benefit if I smoked for decades?
No. The Framingham analysis focused on heavy smokers with 20 or more pack-years, and that group still had clearly lower cardiovascular risk within five years of quitting than people who continued.
I quit 20 years ago. Does my smoking history still count?
In the Framingham data, the gap with never smokers had closed by then. Other studies found some remaining risk at 20 years or more in heavier smokers and for leg artery disease. It is still worth telling your doctor your pack-years and quit date.
Will gaining weight after quitting cancel out the benefit?
Not for the heart, according to three large US cohorts. Weight gain was linked to a temporary rise in type 2 diabetes risk, but quitters had lower cardiovascular death rates than continuing smokers whether or not they gained weight.
Does switching to e-cigarettes count as quitting?
The studies described here measured stopping cigarettes and did not test e-cigarettes. Long-term heart data on vaping are limited, and our vaping guide in the related reading below covers what is known.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
