What Is High Blood Pressure?
Blood pressure is the force exerted by circulating blood against the walls of your arteries. When that pressure is consistently too high, it strains the heart, damages blood vessels, and quietly raises the risk of heart attack, stroke, kidney disease, and vision loss. This is why hypertension is often called the "silent killer" — it typically produces no symptoms, even while causing progressive harm.
Blood pressure is recorded as two numbers: systolic pressure (the pressure when your heart beats) over diastolic pressure (the pressure when your heart rests between beats), measured in millimetres of mercury (mmHg).
Understanding Your Blood Pressure Numbers
| Category | Systolic (mmHg) | Diastolic (mmHg) |
|---|---|---|
| Normal | Less than 120 | Less than 80 |
| Elevated | 120–129 | Less than 80 |
| High (Stage 1) | 130–139 | 80–89 |
| High (Stage 2) | 140 or higher | 90 or higher |
| Hypertensive Crisis | Higher than 180 | Higher than 120 |
A single elevated reading does not confirm hypertension. Diagnosis is typically based on multiple readings taken on separate occasions.
What Causes Hypertension?
In most adults, hypertension has no single identifiable cause — this is called primary (essential) hypertension, and it develops gradually over years due to a combination of genetic and lifestyle factors. A smaller proportion of cases are secondary hypertension, caused by an underlying condition such as kidney disease, thyroid disorders, sleep apnoea, or certain medications.
Key Risk Factors
- Family history of hypertension or cardiovascular disease
- Increasing age (arteries naturally stiffen over time)
- Being overweight or obese
- A high-sodium, low-potassium diet
- Physical inactivity
- Excessive alcohol consumption
- Chronic stress
- Smoking
Why It's So Dangerous Without Symptoms
The absence of symptoms means many people don't know they have hypertension until damage has already occurred. Over time, uncontrolled high blood pressure can cause:
- Heart attack or heart failure — the heart has to work harder, becoming thickened and less efficient
- Stroke — damage to blood vessels in the brain can cause rupture or clot formation
- Chronic kidney disease — the kidneys' delicate filtering vessels are damaged by sustained pressure
- Vision problems — hypertensive retinopathy damages the blood vessels in the eye
- Peripheral artery disease — reduced circulation to the limbs
Managing and Treating Hypertension
Both lifestyle modifications and medications are used, often together:
Lifestyle Changes
- Reduce sodium intake — aim for less than 2,300mg per day; many processed foods are major contributors
- Adopt a heart-healthy diet — the DASH diet (rich in fruits, vegetables, whole grains, and low-fat dairy) has strong evidence for lowering blood pressure
- Exercise regularly — at least 150 minutes of moderate aerobic activity per week
- Limit alcohol — no more than 1–2 standard drinks per day
- Quit smoking — smoking both raises blood pressure and accelerates artery damage
- Manage stress — relaxation techniques, adequate sleep, and social connection all contribute
Medications
When lifestyle changes alone are insufficient, your doctor may prescribe one or more antihypertensive medications. Common classes include ACE inhibitors, ARBs, calcium channel blockers, and thiazide diuretics. The right medication depends on individual factors including age, ethnicity, kidney function, and other health conditions.
Monitoring at Home
Home blood pressure monitors are widely available and can provide valuable data between doctor visits. For accurate readings, sit quietly for five minutes beforehand, avoid caffeine and exercise for 30 minutes prior, and take two or three readings at the same time each day. Share your log with your doctor at appointments.
This article is for informational purposes only. If you are concerned about your blood pressure, seek advice from a qualified healthcare professional.