2002Lancet
Lewington et al.
~1 million adults, 61 studies
From 115/75 upwards, every 20 mmHg higher systolic pressure doubled the risk of dying from heart disease or stroke, with no safe threshold.
Find on PubMed ↗Research library · Heart & fitness
Blood pressure: the silent load on your arteries
The force of blood pushing on your artery walls. High blood pressure rarely causes symptoms, yet it's the world's leading risk factor for death, wearing out the heart, brain, kidneys and eyes year after year.
Strong evidence2×risk of dying from heart disease or stroke for every 20 mmHg higher (top number)Lewington 2002, Lancet, ~1M people in 61 studies
−13%death risk for every 10 mmHg the top number comes downEttehad 2016, Lancet, 123 trials, 600,000+ people
−27%death risk with a target under 120 vs under 140SPRINT 2015, NEJM, 9,361 people
01
The basics
What the two numbers mean
Blood pressure is written as two numbers, like 118/76 mmHg. The top (systolic) number is the peak pressure when your heart squeezes. The bottom (diastolic) number is the pressure while your heart relaxes and refills.
Your arteries are elastic tubes. When pressure stays high, their walls thicken and stiffen, the heart has to work harder and grows thick, and tiny vessels in the brain, kidneys and eyes get damaged. That is why high blood pressure raises the risk of heart attack, stroke, heart failure, kidney disease and dementia.
Current US guidelines call under 120/80 normal, 120–129 'elevated', 130–139 (or 80–89) stage 1, and 140/90 or more stage 2 high blood pressure. Nearly half of adults in many countries have readings above normal, and many don't know it.
Reading the two numbers
Each heartbeat sends a pressure wave through your arteries. The peak is the top number, the trough the bottom number.
02
How it works
How high pressure does damage
1
Arteries
Constant force injures the lining, making it stiffer and easier for plaque to stick.
2
Heart
Pumping against high pressure thickens the heart wall and can lead to heart failure.
3
Brain
Small vessel damage raises the risk of stroke, memory problems and dementia.
4
Kidneys & eyes
Delicate filters and retina vessels get scarred over time.
03
Measure it
How to measure it at home
- Use a validated upper-arm cuff (wrist cuffs are less accurate). Check the cuff size fits your arm.
- Sit quietly for 5 minutes, back supported, feet flat, arm resting at heart level. No coffee, exercise or smoking for 30 minutes before.
- Take 2 readings a minute apart, morning and evening, for 7 days, and average them. Home readings avoid the 'white coat' effect at the clinic.
Try your number
NormalElevatedStage 1 highStage 2 high
95170
Categories from the ACC/AHA guideline. The bottom number counts too: 80–89 is stage 1, 90 or more is stage 2.
04
What the research says
The key studies
2016Lancet
Ettehad et al.
123 trials, 613,815 people
Each 10 mmHg drop in systolic pressure cut major heart events by 20%, stroke by 27%, heart failure by 28% and death by 13%, whatever the starting level.
Find on PubMed ↗2015NEJM
SPRINT Research Group
9,361 adults at high risk
Aiming for under 120 rather than under 140 reduced heart attacks, strokes and heart failure by 25% and deaths by 27%.
Find on PubMed ↗2019JAMA
SPRINT MIND
9,361 adults
The tighter target lowered the risk of mild memory and thinking problems by 19%.
Find on PubMed ↗2013BMJ
He et al.
34 trials
Cutting salt by about 4.4 g a day lowered blood pressure by around 4/2 mmHg on average, and more (5/3) in people with high blood pressure.
Find on PubMed ↗2023Br J Sports Med
Edwards et al.
270 trials, 15,827 people
All exercise types lowered blood pressure, and isometric holds like wall sits and handgrip squeezes gave the largest drop: about 8/4 mmHg.
Find on PubMed ↗05
Take action
How to lower it
Each change below lowers blood pressure by a few points. Together they can match a medicine.
- 1
Eat the DASH way
Plenty of vegetables, fruit, beans, nuts and low-fat dairy, less red meat and sweets. Cut about 11 points in people with high blood pressure (Appel 1997).
- 2
Cut salt, add potassium
Aim for under 5 g salt a day. Most comes from bread, cheese, processed meat and ready meals. Potassium-rich foods (beans, bananas, leafy greens) help.
- 3
Move, including isometrics
Cardio most days, plus 3 sessions a week of 4×2-minute wall sits or handgrip squeezes.
- 4
Lose a little weight
Roughly 1 mmHg lower for every kilogram lost.
- 5
Drink less, sleep better
Alcohol raises pressure. Loud snoring can mean sleep apnea, a common hidden cause.
- 6
Take medicine if needed
If home readings stay at 130/80 or more, talk to your doctor. Pills are safe, cheap and very effective.
06
Myth or fact
Common myths, checked
✕ MythI'd feel it if my blood pressure were high.
✓ FactIt's called the silent killer because most people feel nothing until damage is done.
✕ MythIt's normal for it to rise with age.
✓ FactIt's common, not harmless. Risk keeps climbing with every point.
✕ MythOnce I start pills, I'm on them for life.
✓ FactSome people can reduce or stop medicine after big lifestyle changes. Never stop without your doctor.
✕ MythOnly the top number matters.
✓ FactBoth count, especially the bottom number in people under 50.
07
Questions
Frequently asked
How often should I check?
If it's normal, at least once a year. If it's raised or you're changing treatment, a week of home readings every month or two.
Why is it higher at the doctor's?
'White coat' nerves can add 10 points or more. Home readings give the truer picture.
Is low blood pressure a problem?
Only if it causes dizziness or fainting. Otherwise, lower is usually healthier.
08
Sources
References and related topics
- Lewington et al. (2002). Lancet. ~1 million adults, 61 studies. PubMed ↗
- Ettehad et al. (2016). Lancet. 123 trials, 613,815 people. PubMed ↗
- SPRINT Research Group (2015). NEJM. 9,361 adults at high risk. PubMed ↗
- SPRINT MIND (2019). JAMA. 9,361 adults. PubMed ↗
- He et al. (2013). BMJ. 34 trials. PubMed ↗
- Edwards et al. (2023). Br J Sports Med. 270 trials, 15,827 people. PubMed ↗