High Blood Pressure: The Complete Guide to Numbers, Causes, Treatment and Prevention

High blood pressure is called the “silent killer” because it usually causes no symptoms while quietly damaging the heart, brain, kidneys and eyes. It affects well over a billion adults worldwide, and around half do not know they have it. The good news: it is easy to measure and very treatable.

Imagine a free blood pressure check at a pharmacy or church health fair. The machine reads 168/102. You feel perfectly well, so you assume the machine is wrong. Three years later, a stroke changes everything. This guide is about making sure that story never becomes yours.

What blood pressure is

Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps. It is written as two numbers, such as 120/80 mmHg.,The top number (systolic) is the pressure when the heart beats and pushes blood out. The bottom number (diastolic) is the pressure when the heart relaxes between beats. Both matter, though in older adults the top number is often the stronger predictor of risk.

What the numbers mean

Definitions differ slightly between guidelines. In the UK, clinic blood pressure of 140/90 mmHg or higher, confirmed with home or ambulatory readings of 135/85 mmHg or higher, is used to diagnose high blood pressure (hypertension). The 2017 American College of Cardiology and American Heart Association guideline uses a lower threshold, defining stage 1 hypertension as 130 to 139 systolic or 80 to 89 diastolic, and stage 2 as 140/90 or higher. European guidelines from 2024 introduced an “elevated” category of 120 to 139 systolic.,Whatever the label, the principle is the same: the higher your blood pressure, the higher your risk of heart attack, stroke, heart failure and kidney disease, and lowering it reduces that risk. A reading of 180/120 or higher is very high and needs urgent assessment, especially with symptoms.

Why high blood pressure is dangerous

• It strains the heart, which can thicken and eventually fail
• It damages artery walls, speeding up the build-up of fatty plaques
• It is the single biggest risk factor for stroke worldwide
• It damages the small blood vessels in the kidneys, leading to kidney disease
• It can damage the blood vessels in the eyes
• It is linked to vascular dementia
• In pregnancy, it can cause serious complications for mother and baby

Symptoms (or the lack of them)

Most people with high blood pressure feel completely well. Headaches, nosebleeds and dizziness are often blamed on blood pressure, but they are not reliable signs, and waiting for symptoms means waiting too long.,Very high blood pressure can occasionally cause severe headache, blurred vision, chest pain, breathlessness or confusion. These need urgent medical help. For everyone else, the only way to know is to measure it.

Who should be checked

Adults should have their blood pressure checked regularly, at least every five years from age 40 in many countries, and more often if readings are borderline or you have other risk factors. Many pharmacies, clinics and workplaces offer free checks. People with diabetes, kidney disease, a family history of heart disease or high blood pressure in pregnancy should be checked at least yearly.

Causes and risk factors

• Age: blood pressure tends to rise as arteries stiffen
• Family history
• Ethnicity: people of Black African and African Caribbean descent are more likely to develop high blood pressure, often at a younger age and more severely
• Too much salt
• Being overweight, especially around the waist
• Physical inactivity
• Drinking too much alcohol
• Smoking, which also damages arteries
• Long-term stress and poor sleep, including sleep apnoea
• Some medicines, such as anti-inflammatory painkillers, decongestants, steroids and some contraceptive pills

Secondary hypertension

In most adults, high blood pressure has no single identifiable cause; this is called primary or essential hypertension. In about 5 to 10% of people, a specific cause is found. This is called secondary hypertension.,Causes include kidney disease, narrowing of the kidney arteries, hormone conditions such as primary aldosteronism, Cushing’s syndrome, phaeochromocytoma and thyroid problems, sleep apnoea, and some medicines or drugs. Your healthcare provider may look for these if you are young, your blood pressure is very high or hard to control, it rises suddenly, or blood tests show low potassium.

Measuring blood pressure properly

A single high reading does not mean you have high blood pressure. Readings vary with stress, activity, caffeine, a full bladder and even talking. “White coat hypertension”, where readings are high only in clinics, is common. That is why diagnosis is usually confirmed with home readings or a 24-hour ambulatory monitor.,For an accurate home reading, sit quietly for five minutes with your back supported and feet flat on the floor. Rest your arm on a table at heart level, with the cuff on bare skin. Do not talk. Avoid caffeine, exercise and smoking for 30 minutes before. Take two readings a minute apart, morning and evening, for about a week, and use the average.

Choosing a home monitor

• Choose an automatic upper-arm monitor rather than a wrist or finger device
• Check it has been clinically validated; independent lists of validated monitors are available online
• Make sure the cuff fits your arm; too small a cuff gives falsely high readings
• Bring it to your clinic so it can be checked against their machine
• Keep a record of your readings, or use a monitor that stores them

Salt: the single biggest dietary change

Eating too much salt raises blood pressure in most people. The World Health Organization recommends less than 5 g of salt a day for adults, about one teaspoon. Most adults eat almost double that.,Around three-quarters of the salt we eat is already in food when we buy it: bread, stock cubes, processed meat, cheese, sauces, snacks, instant noodles and ready meals. Cooking from scratch, tasting before adding salt, using herbs, spices, garlic, lemon and pepper for flavour, and checking food labels can make a big difference. Your taste buds adjust within a few weeks, and food will taste salty again with less.

Other food changes that help

• Eat plenty of fruit and vegetables, which are rich in potassium
• Choose wholegrains, beans, lentils, nuts and seeds
• Include low-fat dairy if you eat it
• Limit red and processed meat, sugary drinks and fried foods
• The DASH eating pattern (Dietary Approaches to Stop Hypertension) has strong evidence for lowering blood pressure
• If you have kidney disease, check before increasing potassium-rich foods or using potassium-based salt substitutes

Weight, activity and alcohol

Losing excess weight is one of the most effective ways to lower blood pressure: blood pressure often falls by about 1 mmHg for every kilogram lost. Regular aerobic activity, such as brisk walking for 30 minutes on most days, can lower systolic blood pressure by several points. Resistance and isometric exercises, such as wall squats and handgrip exercises, also help.,Alcohol raises blood pressure, and heavy drinking can make it hard to control. Keeping within recommended limits and having several alcohol-free days a week helps.

Stopping smoking

Smoking does not cause long-term high blood pressure in the same way as salt or weight, but each cigarette raises blood pressure temporarily and damages artery walls. Combined with high blood pressure, smoking greatly increases the risk of heart attack and stroke. Stopping is one of the best things you can do for your heart, and support makes it much more likely to succeed.

Sleep and stress

Poor sleep and untreated obstructive sleep apnoea are linked with high blood pressure that is hard to control. If you snore loudly, stop breathing at night or feel very sleepy during the day, ask about a sleep study.,Long-term stress can contribute to unhealthy habits and higher blood pressure. Regular physical activity, time outdoors, relaxation techniques, social support and talking therapies can help. Meditation and breathing exercises may give modest reductions.

When medicines are needed

Many people need medicines in addition to lifestyle changes, particularly if blood pressure is very high or they have other risks such as diabetes, kidney disease or previous heart disease. Lifestyle changes still matter, because they make medicines work better and may mean you need fewer.,Common medicines include ACE inhibitors (such as ramipril), angiotensin receptor blockers (such as losartan), calcium channel blockers (such as amlodipine) and thiazide-like diuretics (such as indapamide). Beta-blockers, spironolactone and others are used in specific situations. Many people need two or three medicines, often in a single combined tablet, to reach their target.

Choosing a first medicine

Guidelines differ by country, age and ethnicity. For example, UK guidance often suggests an ACE inhibitor or ARB for people under 55 who are not of Black African or African Caribbean family origin, and a calcium channel blocker for people aged 55 and over or of Black African or African Caribbean family origin. Other guidelines recommend starting with a combination of two medicines for many people. Your healthcare provider will consider your other conditions, such as diabetes or kidney disease, and any side effects.

Common side effects to know about

• ACE inhibitors: a dry cough in some people; rarely swelling of the lips or tongue, which is an emergency
• Calcium channel blockers: ankle swelling, flushing, headache
• Diuretics: needing to pass urine more often, low sodium or potassium, gout flares
• Beta-blockers: tiredness, cold hands and feet
• Many medicines can cause dizziness when standing up, especially at first
• Tell your healthcare provider about side effects; there are many alternatives

Taking medicines every day

Blood pressure medicines only work while you take them. Stopping because you feel well, because your readings are now normal, or because of cost is one of the most common reasons for strokes and heart attacks in people with known high blood pressure. Normal readings usually mean the medicines are working.,If cost, side effects or remembering are a problem, tell your healthcare provider or pharmacist. Once-daily combination tablets, cheaper generics, pill organisers and phone reminders can all help.

Resistant hypertension

If blood pressure stays high despite three medicines at good doses, including a diuretic, it is called resistant hypertension. Common reasons include not taking medicines regularly, inaccurate measurement, high salt intake, alcohol, sleep apnoea, other medicines such as anti-inflammatory painkillers, and secondary causes. Specialist assessment can help, and additional medicines such as spironolactone are often effective.

High blood pressure in pregnancy

Pregnancy can cause new high blood pressure (gestational hypertension) or pre-eclampsia, a serious condition affecting the placenta, kidneys, liver and brain. Pre-eclampsia can develop quickly and can be dangerous for both mother and baby.,Blood pressure and urine are checked at every antenatal appointment for this reason. Seek urgent help if you are pregnant and have a severe headache, problems with vision such as blurring or flashing lights, pain just below the ribs, vomiting or sudden swelling of the face, hands or feet. Some women at higher risk are advised to take low-dose aspirin from early pregnancy. Women who had high blood pressure in pregnancy have a higher lifetime risk and should have their blood pressure checked regularly afterwards.

Hypertensive emergencies

Blood pressure of 180/120 mmHg or above with symptoms such as chest pain, breathlessness, severe headache, confusion, weakness, numbness, vision changes or difficulty speaking may indicate organ damage and is an emergency. Call your local emergency number. If your reading is very high but you have no symptoms, rest for a few minutes, recheck, and contact a healthcare provider the same day.

Stroke warning signs: BE FAST

• Balance: sudden loss of balance or coordination
• Eyes: sudden loss of vision
• Face: drooping on one side
• Arms: weakness or numbness in one arm
• Speech: slurred or strange speech
• Time: call emergency services immediately

High blood pressure in children and young adults

High blood pressure is increasingly seen in children and young adults, linked to rising obesity, inactivity and high-salt diets. It can also be caused by kidney or hormone conditions. Young people with high readings should be properly assessed, as early treatment and lifestyle change can prevent decades of damage.

Older adults

Blood pressure targets for older adults are individual. For many people over 80, a target below about 150/90 mmHg in clinic is used, while fitter older adults may be treated to lower targets. Treatment still reduces strokes and heart failure in older people.,Older adults are more prone to dizziness and falls when standing up (postural hypotension), especially with several medicines. Blood pressure should sometimes be checked both sitting and standing. If you feel light-headed on standing, get up slowly and tell your healthcare provider.

Blood pressure and kidney disease

High blood pressure damages the kidneys, and kidney disease raises blood pressure, creating a vicious cycle. People with chronic kidney disease, especially with protein in the urine, often benefit from ACE inhibitors or ARBs and lower blood pressure targets. Regular kidney blood and urine tests are part of good blood pressure care.

Blood pressure and diabetes

High blood pressure is very common in people with diabetes, and the combination greatly increases the risk of heart disease, stroke, kidney disease and eye damage. Blood pressure targets are often lower for people with diabetes, especially those with kidney disease, and ACE inhibitors or ARBs are commonly used.

Low-cost ways to stay on track

• Get a validated home monitor and check regularly once controlled, for example a few days each month
• Keep a simple log on paper or your phone
• Bring your readings to every appointment
• Ask for a once-daily combination tablet if you take several medicines
• Use the same pharmacy so interactions can be checked
• Involve family members in healthier cooking and walking

Myths about blood pressure

• “I would feel it if my blood pressure was high.” Usually you would not
• “Once it is normal, I can stop my tablets.” It is normal because of the tablets
• “Herbal remedies are safer.” Some can raise blood pressure or interact with medicines; check first
• “Only older people need to worry.” Young adults can and do have high blood pressure
• “Sea salt or pink salt is healthier.” It contains the same sodium

High blood pressure around the world

The World Health Organization’s first global report on hypertension in 2023 estimated that around 1.3 billion adults aged 30 to 79 have high blood pressure, and that only about one in five has it under control. Many people in low- and middle-income countries are undiagnosed because checks and affordable medicines are not easily available.,Simple, low-cost actions such as regular community blood pressure checks, reducing salt in processed foods, and access to generic once-daily medicines could prevent millions of heart attacks and strokes. Nurses and community health workers are central to this work in many countries.

Questions to ask your healthcare provider

• What is my target blood pressure?
• Should I be checking at home, and how often?
• What is my overall risk of heart attack and stroke?
• Do I need blood tests for kidney function, cholesterol or diabetes?
• Which lifestyle change would help me most?
• What should I do if I get side effects from my medicine?

A week of small changes

Big changes are hard to sustain, so many people do better with small, steady steps. In week one, you might stop adding salt at the table and swap one processed snack for fruit. In week two, add a brisk 15-minute walk after one meal each day. In week three, cut down on stock cubes and salty sauces by flavouring food with herbs, garlic, ginger and lemon. In week four, have two alcohol-free days.

Each change may lower blood pressure by only a few points, but together they add up, and many people find they feel more energetic as well.

How nurses and pharmacists can help

You do not always need to see a healthcare provider-led clinic for blood pressure care. In many countries, practice nurses, community nurses and pharmacists run blood pressure checks, medicine reviews and lifestyle support. They can teach you to use a home monitor correctly, check whether your medicines are causing side effects, and help you set realistic goals. Make use of these services; regular contact is one of the best predictors of good control.

Family and community

High blood pressure often runs in families, partly through genes and partly through shared habits such as salty cooking. Encourage relatives over 40, and younger relatives with risk factors, to get their blood pressure checked. Cooking with less salt as a household protects everyone, including children, whose taste preferences form early. Community health days, workplace checks and faith-based health programmes are valuable places to find undiagnosed high blood pressure.

Frequently asked questions

Is 130/80 high blood pressure?

It depends on the guideline. In the US it is classed as stage 1 hypertension; in the UK and many other countries it is considered high-normal. Either way, lifestyle changes are worthwhile.

Does coffee raise blood pressure?

Caffeine can cause a short-term rise. Moderate coffee drinking is usually fine, but avoid it before a blood pressure check.

Can stress alone cause high blood pressure?

Stress causes short-term rises and can contribute to long-term high blood pressure, often through sleep, diet and alcohol.

Can high blood pressure be cured?

It is usually a long-term condition, but lifestyle changes can bring it down substantially, and some people can reduce or stop medicines under supervision.

Is it safe to exercise with high blood pressure?

Yes, for most people, and it helps lower blood pressure. If your blood pressure is very high or uncontrolled, check with your healthcare provider first.

But I feel fine. Why take tablets for a number?

Because that number predicts strokes, heart attacks and kidney failure years before they happen. Treating it while you feel well is what keeps you feeling well.

Related: How to check blood pressure at home · Blood pressure chart by age · ACE inhibitors · Stroke: BE FAST

Sources: World Health Organization Global report on hypertension (2023), National Institute for Health and Care Excellence (NG136), American College of Cardiology/American Heart Association 2017 guideline, European Society of Cardiology 2024 guidelines, British Heart Foundation.