What Is High Blood Pressure (Hypertension)? Causes and Risks

High blood pressure, also called hypertension, is very common, and many people do not know they have it. Left untreated it can damage the heart and blood vessels over time. This article explains what it is, what raises the risk and how it is found and managed, using information from the NHS, the US CDC and the WHO.

What is high blood pressure?

Blood pressure is the force of blood pushing against the walls of your arteries as the heart pumps. The CDC describes high blood pressure as pressure that stays at or above 130/80 mm Hg, with a normal reading being below 120/80. The WHO and the NHS use somewhat different cut-offs for diagnosis, which are explained in our article on blood pressure numbers. What matters most is that a health professional measures it and tells you what your readings mean.

Why it matters

The NHS says high blood pressure can lead to serious problems such as heart attacks and strokes. Left untreated, it can also raise the risk of heart disease, heart failure, kidney disease and vascular dementia. The CDC lists further effects on the heart, brain, kidneys and eyes, and notes links to pregnancy-related complications. The WHO calls hypertension a major cause of premature death.

According to the WHO, about 1.4 billion adults aged 30 to 79 had hypertension in 2024. It estimates that around 44% of them were unaware they had it, and that about 23% had it under control.

Symptoms

Most people feel nothing. The NHS, CDC and WHO all say that measuring blood pressure is the only reliable way to find out. This is why regular checks matter, even if you feel well.

Causes and risk factors

The NHS lists these things that can make high blood pressure more likely:

• Getting older
• Having close relatives with high blood pressure
• Black African, Black Caribbean or South Asian background
• An unhealthy diet, especially one high in salt
• Being overweight
• Smoking
• Drinking too much alcohol
• Long-term stress

The WHO groups risks into those you can change, such as a diet high in salt, inactivity, tobacco, alcohol and overweight, and those you cannot, such as family history, age over 65, and conditions like diabetes or kidney disease. The CDC also lists pregnancy and long-term depression, anxiety or stress.

How it is found and managed

A health professional measures blood pressure with a cuff around the upper arm. The NHS says that if high readings are suspected you may be asked to monitor at home for several days, return for another check weeks later, or wear a monitor that records your blood pressure over 24 hours.

Management usually starts with healthy habits. The NHS says doctors will usually prescribe medicine if blood pressure is very high, if you have a higher risk of heart attack or stroke, or if it stays high despite lifestyle changes. The WHO names classes of blood pressure medicines, including ACE inhibitors, angiotensin receptor blockers, calcium channel blockers and diuretics. Which medicine suits you, and whether you need one, is for your doctor to decide. The CDC and WHO both stress taking medicines as prescribed and not stopping them without talking to your doctor.

The NHS also says even a small drop in blood pressure can lower the chance of complications.

When to see a doctor

The NHS advises getting your blood pressure checked if you think you may be at risk, and if you are 40 or over and have not had it checked in the last 5 years. Many pharmacies offer checks. Get urgent medical advice if you often have headaches or blurred vision, or if you have chest pain that comes and goes.

Call emergency services immediately for sudden chest pain that does not go away, pain spreading to the arms, neck, jaw, stomach or back, or chest pain with sweating, sickness, light-headedness or breathlessness. The NHS says not to drive yourself to hospital.

In an emergency, call your local emergency number (112 in India, 911 in the United States).