Long-term exposure to the harmful substances in tobacco increases the risk of many conditions, including stroke. People who smoke 20 cigarettes daily are six times more likely to have a stroke than people who do not smoke.

This data comes from the World Stroke Organization.

Smoking increases the risk of stroke because it causes inflammation and damage to the blood vessels and can lead to a buildup of plaque in the arteries. This makes it harder for the heart to pump blood. Smoking also impacts circulation throughout the body by constricting small arteries.

This article examines the relationship between smoking and stroke and how to reduce the risk.

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Yes, smoking can lead to a stroke.

Tobacco smoke contains thousands of toxic and cancer-causing chemicals that pass from the lungs into the bloodstream when a person inhales it. These chemicals alter and damage cells and increase the risk of stroke and other cardiovascular diseases.

There are several ways smoking raises the risk of stroke. It affects:

  • Cholesterol: Smoking reduces ‘good’ high-density lipoprotein (HDL) cholesterol and increases ‘bad’ low-density lipoprotein (LDL) cholesterol.
  • Oxygen levels: Tobacco smoke contains carbon monoxide, which reduces the amount of oxygen in the blood.
  • Blood pressure: Tobacco contains nicotine, which elevates heart rate and blood pressure. Half of all strokes have links with high blood pressure.
  • Blood clotting: The chemicals in tobacco smoke thicken the blood and make it more prone to clotting.

Together, these effects increase the risk of the arteries narrowing and hardening. This is known as atherosclerosis.

When arteries become narrow and less flexible, it reduces blood flow, raises blood pressure, and increases the likelihood of blood clots. Blood clots can travel and become lodged in the brain, potentially causing a stroke.

There are two primary types of stroke. Most strokes are ischemic, meaning a blood clot blocks blood vessels in the brain. Fatty plaque deposits on the blood vessel walls can also cause blockages.

The other type of stroke is a hemorrhagic stroke, which occurs when an artery in the brain bursts — either because of weak walls or high blood pressure. The leaking blood puts too much pressure on brain cells and damages them.

Smoking can contribute to both types of stroke. It narrows the blood vessels and can lead to plaque and clot formation, increasing the risk of an ischemic stroke. The chemicals in cigarette smoke can also weaken arteries, making them more prone to bursting, leading to a hemorrhagic stroke.

Doctors associate smoking with a 2- to 4-time increased risk of ischemic stroke and intracranial bleeds, meaning bleeding in the brain.

It is difficult to say how many cases of stroke have direct links to smoking.

An older study from 2010 found that out of 3,000 strokes in 22 countries, smoking was a factor in around 19% of them.

If this figure were correct for the United States, too, it would mean that around 152,000 of the 800,000 strokes that occur annually nationwide have links with smoking.

However, as the 2010 study used data from around the world, this estimate may not be accurate for the U.S. specifically.

Secondhand smoke also raises the risk of stroke. This includes smoke that comes from lit cigarettes or other tobacco products that a person is not smoking themselves or tobacco smoke that is in the air.

Even if a person does not smoke, breathing in someone else’s smoke increases the risk of stroke. People living with others who smoke are around twice as likely to experience a stroke than those who live with people who do not smoke.

There is no evidence that quitting smoking can cause a stroke. Rather, quitting can reverse some of the damage that smoking has done to the arteries and lower blood pressure, which decreases stroke risk.

However, it takes 2–4 years after stopping smoking for the excess stroke risk to decrease. This means a person will still have an increased risk of stroke during this time, even if they have stopped completely.

A person may still have a stroke after stopping smoking, but this does not mean smoking cessation caused it.

The best way to reduce the risk of stroke is to follow a healthy lifestyle wherever possible.

Quit smoking

Quitting smoking significantly lowers the chance of stroke, as well as other conditions. These include:

  • cancer
  • heart attack
  • chronic obstructive pulmonary disease

Many resources are available to help someone quit smoking, such as nicotine replacement therapies, counseling, and support groups. The U.S. government’s Quit Smoking website provides information on quitting and can refer people to local services.

Eat a balanced diet

Eating a balanced diet can reduce the risk of stroke. Try to include:

  • plenty of vegetables
  • fresh fruit
  • whole grains
  • lean protein
  • healthy fats, such as olive oil and avocado

People should avoid excessive amounts of salt, as well as processed foods, added sugars, and saturated fats. They should also choose high-fiber foods when possible.

Exercise regularly

Regular physical activity can lower the risk of stroke by improving circulation, balancing cholesterol levels, and reducing blood pressure. The Centers for Disease Control and Prevention (CDC) recommend 2.5 hours of moderate-intensity aerobic activity per week for adults.

Control medical conditions

Certain medical conditions can increase the risk of stroke, such as high blood pressure and diabetes. Taking medication and following doctors’ orders can help control these conditions, reducing the risk of stroke.

Smoking can significantly increase the chance of stroke by damaging blood vessels, triggering plaque or clot formation, or weakening blood vessels. If a clot occurs and travels to the brain, or if blood vessels in the brain burst, it will cause a stroke.

People can lower their risk of stroke by quitting smoking. Other things that decrease the risk include eating a balanced diet, exercising regularly, and controlling medical conditions.

Making these changes can be difficult. If a person wants help or advice on quitting smoking or lowering their stroke risk, they can contact a medical professional.