What does high blood pressure do to your body?
It strains your heart, brain, kidneys and eyes, usually with no symptoms. But the risk isn’t fixed. In big treatment trials, a 10-point drop in the top number cut strokes by about a quarter.
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What are the risks of high blood pressure?
High blood pressure puts extra strain on your blood vessels, your heart and other organs. That includes your brain, kidneys and eyes.
If it’s not treated, the NHS says it can raise your risk of heart disease, heart attacks, strokes, heart failure, kidney disease and vascular dementia.
| Part of your body | What it can lead to |
|---|---|
| Arteries | They lose their stretch and get stiff or narrow. Fatty material builds up more easily. |
| Heart | Heart disease, heart attacks and heart failure. |
| Brain | Stroke, and vascular dementia, which affects memory and thinking. |
| Kidneys | Kidney disease. Damaged kidneys can push blood pressure even higher. |
| Eyes | Loss of vision, if it’s not treated. |
| Legs | Narrowed leg arteries, which can cause pain when you walk. |
| Sex | Sometimes, problems getting or keeping an erection. |
Sources: NHS; BHF; Blood Pressure UK; Blood Pressure UK: erections
Think of a garden hose left at full pressure for years. The rubber gets stiff, and it can clog or split.
Your arteries are similar. The BHF says high blood pressure makes them lose their stretch.
That doesn’t mean a stroke or heart attack tomorrow. It does make one more likely.
Feel fine? High blood pressure does not usually cause symptoms. Many people have it without knowing.
So your next step is to know your number. Many pharmacies offer free checks if you’re 40 or over.
How does high blood pressure cause a stroke?
Blood Pressure UK calls it the single biggest cause of stroke. A stroke is when blood can’t reach part of the brain.
How years of high pressure can lead to a stroke
- 1
Vessels damaged
Uncontrolled high blood pressure damages your blood vessels.
- 2
Narrow or weak
Over time they get narrower and stiffer, or weaker.
- 3
Block or burst
A vessel can get blocked, or it can burst.
- 4
Brain loses blood
Blood stops reaching part of the brain, so it gets no oxygen.
Source: Blood Pressure UK
The same damage to blood vessels in the brain can lead to vascular dementia. It’s the second most common type of dementia. The NHS lists high blood pressure as one thing that raises your chances.
Learn FAST now, so you know it when it counts.
Face fallen on one side? Can they smile?
Arms: can’t raise both and keep them there? Speech slurred?
Time to call 999 if you see any one of these signs. Call even if they pass quickly.
What does high blood pressure do to your heart?
It makes your heart work harder. Over time, Blood Pressure UK says, your heart can become enlarged or weak.
Harder work helps at first, then wears the heart down
- 1
Pumps harder
When blood pressure is very high, the left side of your heart works harder.
- 2
Muscle grows
The muscle gets bigger to cope. This protects the heart at first.
- 3
Works less well
In the long run, the bigger muscle is less able to do its job.
- 4
Heart failure
The heart can’t pump blood round your body as well as it should.
Source: Blood Pressure UK
Heart failure doesn’t mean your heart is about to stop. But it can be serious.
The strain can also lead to coronary heart disease. That’s when the arteries to your heart get too narrow. It can cause chest pain and heart attacks.
Men: trouble getting an erection can be a sign of high blood pressure and heart disease. If that’s you and you don’t know your numbers, speak to your GP and get checked. Everyone else: if you don’t know your numbers, get a free check at a pharmacy.
How do kidneys and blood pressure affect each other?
Both ways. High blood pressure can damage your kidneys, and damaged kidneys can raise your blood pressure.
Narrow vessels mean less blood reaches the kidneys, so they scar. The kidneys then make hormones that push blood pressure higher still. Blood Pressure UK calls this a vicious cycle.
Early kidney disease often has no signs. That’s why NICE says everyone with high blood pressure should be offered a few simple checks.
| Check | What it looks at |
|---|---|
| Urine test | Protein or blood in your wee, which can show kidney damage. |
| Blood test | How well your kidneys filter (eGFR), plus blood sugar and cholesterol. |
| Eye check | The back of your eyes, for damage from high blood pressure. |
| ECG (heart tracing) | Your heart rhythm and signs of strain. |
Sources: NICE NG136; Blood Pressure UK; BHF
NICE also says your GP should work out your risk of heart and circulation disease. Ask if these checks are done. See what a kidney function test shows.
Does lowering blood pressure cut the risks?
Yes. The NHS says lowering it even a small amount can help cut your risk.
A 2016 review in The Lancet pooled 123 trials of blood pressure treatment, with over 600,000 people.
| Problem | Change |
|---|---|
| Stroke | About 27% fewer |
| Heart failure | About 28% fewer |
| Coronary heart disease | About 17% fewer |
| All major heart and circulation problems | About 20% fewer |
| Deaths from any cause | 13% fewer |
| Kidney failure | No clear change |
Source: Ettehad et al, The Lancet 2016
That top number is your systolic pressure, the pressure as your heart pumps. These are averages from trials, not a promise for one person.
If you have high blood pressure and you’re under 80, NICE aims for a clinic reading below 140/90. People with type 1 diabetes or severe kidney disease may have a different aim, so ask your GP. At 80 or over, it aims for below 150/90.
Six NHS changes that help lower blood pressure
- Avoid salty food and adding salt to your meals.
- Lose weight if you’re overweight.
- Avoid drinking more than 14 units of alcohol a week on a regular basis.
- Aim for at least 150 minutes of exercise a week.
- Cut down on caffeine, such as coffee, tea and cola.
- Don’t smoke.
Source: NHS: high blood pressure
A GP may also offer tablets. Never stop or change a prescribed medicine without your prescriber.
Pick one change to start this week. See what causes high blood pressure and which exercise helps most.
When to speak to a GP
The only way to know your blood pressure is to get it checked. Speak to a GP if:
- Your reading is 140/90 or more at a pharmacy or surgery, or 135/85 or more at home. That usually counts as high.
- You’re 40 or over and haven’t had it checked for more than 5 years.
- Your legs hurt when you walk, and the pain goes after a short rest. This can be a sign of narrowed leg arteries.
- You have trouble getting an erection and don’t know your blood pressure numbers.
Get help from NHS 111 if you often have headaches or blurred vision, or chest pain that comes and goes. Also get help for other symptoms you’re worried could be from high blood pressure.
Call 999 for sudden chest pain or discomfort that doesn’t go away, such as squeezing, pressure, burning or indigestion. Also call for pain spreading to either arm, your neck, jaw, stomach or back.
Call 999 too for chest pain with sweating, feeling sick, light-headed or short of breath. Do not drive yourself to A&E. Call 999 for any FAST sign of a stroke.
To read your numbers, see blood pressure readings explained and how to measure at home.