The Condition You Cannot Feel
High blood pressure usually causes no symptoms at all. That is the whole problem with it. Hypertension is a long-term condition in which the pressure of blood in the arteries stays persistently elevated, and about half of all people who have it do not know.
It is normally picked up by chance, during a health screening or while seeking care for something unrelated. Some people do report headaches, lightheadedness, vertigo, tinnitus, altered vision or fainting, but these may be caused by associated anxiety rather than by the pressure itself.
Left alone for years, it does visible damage. Doctors can see changes at the back of the eye, a condition called hypertensive retinopathy, whose severity roughly tracks how long and how badly the blood pressure has been raised. It also causes chronic kidney disease and thickening of the heart muscle.
Two Numbers, and What They Mean
Blood pressure is written as two measurements: the systolic pressure first, then the diastolic, both in millimetres of mercury.
For most adults, normal resting blood pressure is under 120 systolic and 80 diastolic. Elevated means a systolic reading between 120 and 129 with a diastolic under 80. High blood pressure is diagnosed when the resting pressure is persistently at or above 130/80, which is stage 1, or 140/90, which is stage 2. Children are assessed against different numbers.
Where you take the reading matters too. Ambulatory blood pressure monitoring, which records readings over a full 24-hour period as a person goes about their day, appears to be more accurate than a single measurement taken in a clinic.
Primary, Secondary, and the Everyday Causes
Hypertension splits into two kinds. About 90 to 95% of cases are primary hypertension, also called essential hypertension, meaning high blood pressure arising from non-specific lifestyle and genetic factors rather than one identifiable cause.
The lifestyle factors that raise the risk are familiar and mostly unglamorous: excess salt in the diet, excess body weight, smoking, physical inactivity and alcohol use.
The remaining 5 to 10% is secondary hypertension, where there is a clear identifiable cause. These include chronic kidney disease, narrowing of the arteries supplying the kidneys, an endocrine disorder, or the use of birth control pills. Secondary cases often bring their own distinctive signs, which is frequently how the underlying condition gets caught.
Why It Matters, and What Works
Hypertension affects 33% of the world's population and is a major cause of premature death. In 2019 it was believed to be a factor in 19% of all deaths globally, around 10.4 million people.
The reason is the length of the list it feeds into. High blood pressure is a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease and dementia.
The encouraging part is how treatable it is. Lifestyle changes come first: weight loss, physical exercise, less salt, less alcohol and a healthy diet. If those are not enough, medication follows, and up to three drugs taken together control blood pressure in 90% of people. Treating moderately high pressure, above 160/100, is associated with improved life expectancy. For readings between 130/80 and 160/100 the evidence is less clear cut, with some reviews finding benefit and others finding little or none.
