Hypertension

Blood pressure describes the force of blood against artery walls. A reading has two numbers: systolic pressure, recorded as the heart beats, and diastolic pressure, recorded as it relaxes between beats. A single measurement can vary with activity and circumstances, so clinical diagnosis generally relies on repeated readings. Thresholds are not identical in every guideline: the World Health Organization defines hypertension in adults as readings of at least 140/90 mmHg on two different days, while current U.S. guidance uses a lower threshold. Interpretation also depends on the person and clinical setting.

Most hypertension is classed as primary, or essential: it develops over time without a single identifiable cause. Secondary hypertension results from another condition or from certain medicines. Risk is influenced by a combination of factors, including age and family history, high salt intake, physical inactivity, excess body weight, tobacco use and heavy alcohol consumption. Kidney disease and some other medical conditions can also contribute. These factors alter the likelihood of hypertension; they do not mean that every person with one of them will develop it.

Hypertension often produces no clear symptoms, which is why measurement is important for identifying it. When blood pressure remains high, the added strain can injure blood vessels and organs. It is a major risk factor for cardiovascular disease and can contribute to heart attack, stroke and kidney disease. The absence of symptoms therefore does not establish that blood pressure is normal; health professionals assess it with appropriate measurements rather than by appearance or how a person feels.

The World Health Organization estimated that 1.4 billion adults aged 30–79 had hypertension worldwide in 2024, about one-third of people in that age group. Many affected people are unaware of their condition, and the proportion whose blood pressure is controlled remains substantially smaller than the proportion diagnosed. Prevention and management combine public-health measures, healthier diet and physical activity with clinical monitoring; some people also need prescribed medicines. The appropriate approach varies by individual and is determined with health professionals.