High blood pressure: causes, risks, and prevention

Your guide to high blood pressure and how you can prevent it.

Author: Dr Joshua Smith - Research Scientist MBBS, BMedSci, PGCertMedEd

Reviewed by: Dr Sam Rodgers - Chief Medical Officer, MBBS, MRCGP

Published on: 08 February 2022

Around one in three adults in the UK has high blood pressure (hypertension). In England alone, there are more than five million people left undiagnosed [1]. But what makes high blood pressure so dangerous?

High blood pressure is sometimes referred to as a silent killer because most people don’t have symptoms, and yet it can put you at increased risk of heart disease, heart attacks, stroke, vascular dementia, and kidney disease.

Here, we look at some of the causes of high blood pressure, the potential risks, and how you can keep yours in check.

What is classed as high blood pressure?

The only way to find out if your blood pressure is high is to measure it. You’ll get two values, a systolic and a diastolic pressure.

We’re all unique — a normal blood pressure for one person may in fact be quite high for someone else. But to keep things simple, we use arbitrary cut-off points based on the general population.

An ideal blood pressure is between 90/60 mmHg and 120/80 mmHg. If it climbs above 140/90 mmHg, it is classed as high blood pressure (hypertension). Each stage of hypertension carries its own level of risk.

	Clinic blood pressure
Stage 1 hypertension	Between 140/90 mmHg and 160/100 mmHg
Stage 2 hypertension	Between 160/100 mmHg and 180/120 mmHg
Stage 3 hypertension	180/120 mmHg or higher

If you have measured your blood pressure at home and it is high, use the NHS blood pressure checker to see what steps you should take next.

What are the risks of high blood pressure?

Occasional spikes in blood pressure are not usually a problem, for example, rushing to catch a bus. But when blood pressure remains high for a long period, it can damage your heart and the blood vessels around the body, including those in the brain, kidneys, and eyes.

High blood pressure can quietly damage your body for years before symptoms develop, which is why it’s important to check yours every now and again.

Persistent high blood pressure increases your risk of:

Stroke
Heart attacks
Heart disease
Heart failure
Kidney disease
Vascular dementia
Peripheral arterial disease
Aortic aneurysm
Visual loss

Lowering your blood pressure, even just a little, can reduce your risk of developing these conditions.

Having high cholesterol also contributes to vascular disease — if you do have high blood pressure, it’s worth getting a Cholesterol Blood Test too. You can then use the QRISK tool to work out your risk of developing a heart attack or stroke over the next ten years.

What are the causes of high blood pressure?

Blood pressure is influenced by many different factors.

Some factors, like your genetics and your age, are fixed, and you can’t change that. For example, if you have a relative with high blood pressure, or if you’re of black African, black Caribbean or South Asian descent, you’re more likely to have high blood pressure.

But just as important, if not more so, are your lifestyle choices. These can be changed, and they have a big influence, not just on your blood pressure, but your overall health.

Lifestyle factors that increase your risk of high blood pressure [2]:

Smoking
Being overweight
Physical inactivity
Drinking too much coffee or caffeine
Disturbed sleep routine or not enough sleep
Eating too much salt
High levels of stress — you can check your stress hormone levels with our Stress Cortisol Saliva Test

In about one in 20 cases, high blood pressure is due to an underlying health condition, known as secondary hypertension. Treating the underlying condition usually helps to normalise blood pressure.

Medical conditions that can cause high blood pressure:

Diabetes
Kidney disease
An over- or underactive thyroid
Obstructive sleep apnoea — a condition where the walls of the throat relax and narrow during sleep
Adrenal gland tumours

If you’re concerned, you can check your thyroid with our Advanced Thyroid Function Blood Test or check for diabetes with our Diabetes (HbA1c) Blood Test.

Certain drugs can also raise your blood pressure. But if you’re considering stopping any medications, discuss it with your doctor first — sometimes the benefit outweighs the risk of its side effects.

Medications that may increase your risk of high blood pressure include [3]:

The contraceptive pill
Steroids
Ibuprofen and naproxen
Decongestants
Some recreational drugs like cocaine and amphetamines
Some antidepressants
Some herbal medications like St. John’s Wort or liquorice
Anabolic steroids

How can I reduce my blood pressure

If you have raised blood pressure, your doctor is likely to recommend lifestyle changes in the first instance before discussing medications. This is the most effective and safest way to control your blood pressure and will also help other aspects of your health.

Ways you can safely reduce your blood pressure:

Cut back on alcohol or go teetotal — find out how you can safely cut down alcohol at home
Stop smoking – NHS stop smoking services can help you quit
Lose weight if you’re overweight
Exercise regularly — aim for at least 150 minutes of moderate intensity activity a week
Aim for less than 6g of salt a day (about a teaspoonful)
Drink less caffeine
Manage stress with yoga, mindfulness, or other relaxing activities — here are our top ten ways to de-stress.

What other treatments are there for high blood pressure?

If lifestyle changes are not enough to lower your blood pressure into your target range, you might be prescribed a medication, called an antihypertensive.

There are many different types of antihypertensive, and the one you take will depend on your age, ethnicity, medical conditions, and how well you tolerate it. Often, you’ll start at a low dose which is gradually increased. If one treatment is not enough, your doctor may prescribe two or three for you to take at once.

Taking medications does not mean you should stop trying to lower your blood pressure through lifestyle changes. In fact, leading a healthier lifestyle may reduce your need to take blood pressure tablets altogether.