Prevention

Risk factors are things that can cause a stroke or make it more likely to happen. They are different for everyone.

You can change many of the common risk factors and lower your chance of stroke with some simple steps. Talk your doctor or pharmacist about these stroke risk factors:

• High blood pressure can damage the walls of blood vessels, and it can lead to heart problems. It can cause clots or plaques to break off and block an artery in the brain. High blood pressure is also the strongest risk factor for haemorrhagic stroke. Read more about high blood pressure
  
  
• Type 2 diabetes affects how well the body absorbs glucose, which is a type of sugar. It can lead to fatty deposits or clots in blood vessels. Read more about type 2 diabetes
  
  
• Cholesterol can build up in plaques on the walls of arteries, narrowing the artery and leading to a clot. Read more about cholesterol lowering to prevent another stroke
  
  
• Atrial fibrillation, or irregular heartbeat, causes stagnant blood flow through the heart, and can cause a clot that then goes to the brain. Read more about atrial fibrillation
  
  
• Inactivity or lack of exercise increases your risk of type 2 diabetes, being an unhealthy weight, high blood pressure and high blood cholesterol. Read more about physical activity
  
  
• Diet can affect blood pressure, type 2 diabetes, cholesterol, heart disease, kidney disease and some cancers. Read more about diet after stroke
  
  
• Smoking doubles your risk of stroke by damaging blood vessel walls, increasing blood pressure, reducing oxygen in the blood, and making blood more likely to clot. Read more about smoking
  
  
• Alcohol can cause high blood pressure and atrial fibrillation. It can contribute to uncontrolled diabetes and being an unhealthy weight. Read more about alcohol after stroke

Other risk factors

There are other risk factors that you can talk to your doctor about. Find out what you can do to make a stroke less likely.

• Having had a stroke means you’re more likely to have another one.
• Older age makes a stroke more likely. Your doctor will consider your age with other risk factors.
• Being male means a higher stroke risk at nearly every age, even though women have their own risk factors like pregnancy, oral contraception and hormone replacement therapy. Read about these below.
• Family history can mean a higher stroke risk. For example, high cholesterol can run in families.
• Heart conditions can cause a clot to form and travel to the brain. They include a hole in the heart (patent foramen ovale, or PFO) and heart disease.
• Blood vessel problems make a bleed more likely. They include weak spots that balloon out (aneurysm), tangled arteries and veins (arteriovenous malformation, or AVM), or a ‘cavern’ made of tiny blood vessels (cavernous malformation, or cavernoma).
• Blood disorders can make clots more likely. They include essential thrombocytosis, polycythaemia vera, antiphospholipid syndrome, and sickle cell anaemia.
• Genetic disorders can mean a higher risk of specific types of stroke that run in families. For example, CADASIL (strokes in small blood vessels), vascular Ehlers-Danlos syndrome (arteries more likely to break), and fibromuscular dysplasia (damages walls of arteries in the neck).
• Autoimmune conditions can inflame the walls of blood vessels. This makes them narrower and more likely to clot.
• Infections, such as bacterial heart infections and COVID-19, can cause clots.
• Medication like blood thinners reduce your chance of an ischaemic stroke or clot. But they can also raise your risk of a haemorrhagic stroke or bleed.
• Illegal drugs, such as amphetamine and cocaine, can increase your risk of stroke, especially bleeds.
• Trauma, such as an injury to the head or neck, can break blood vessels. This can cause a bleed or a clot.
• Pregnancy can increase blood pressure, especially with pre-eclampsia and eclampsia. It can also cause gestational diabetes.
• Oral contraception, particularly pills containing a higher dose of oestrogen.
• Hormone replacement therapy is associated with a small increase in the risk of stroke.
• Migraine with aura can affect blood vessels and make a stroke more likely.

Sometimes, a cause can’t be found even after lots of tests. This is called a cryptogenic stroke. If the cause of your stroke is unknown, it’s important to talk with your doctor about what they have done to find the cause, and what you can do to reduce your risk of another stroke.

It's common to worry when a cause can't be found. Contact StrokeLine for advice and support.

For more on the possible ways a stroke can happen, see Types of stroke.