Conditions
High blood pressure: what the numbers mean and what lowers them
Blood pressure categories explained, why high blood pressure matters, common causes, proven ways to lower it and when a reading needs urgent care.
Key takeaways
- High blood pressure usually has no symptoms, so measuring it is the only way to know.
- Less salt, more activity, a healthy weight, limiting alcohol and not smoking all lower it.
- Many people also need medicine, which is safe, effective and often inexpensive.
Blood pressure is the force of blood pushing against the walls of your arteries. It is written as two numbers: systolic (the pressure when your heart beats) over diastolic (the pressure between beats), measured in millimetres of mercury (mmHg).
More than a billion adults worldwide live with high blood pressure (hypertension), and many do not know it. Over time it damages blood vessels and raises the risk of heart attack, stroke, kidney disease, dementia and vision loss.
What the numbers mean
| Category | Systolic | Diastolic | |
|---|---|---|---|
| Normal | below 120 | and | below 80 |
| Elevated | 120–129 | and | below 80 |
| Stage 1 high | 130–139 | or | 80–89 |
| Stage 2 high | 140 or more | or | 90 or more |
| Severe | 180 or more | and/or | 120 or more |
These are US categories from the American Heart Association and American College of Cardiology. Some countries, including the UK, use 140/90 as the clinic threshold for diagnosis. Check a reading with our blood pressure checker.
If your reading is 180/120 or higher, wait five minutes and measure again. If it is still that high, contact a doctor straight away. Call your emergency number if you also have chest pain, shortness of breath, back pain, numbness or weakness, vision changes or difficulty speaking.
Why it happens
For most adults there is no single cause. Risk rises with age, family history, too much salt, low physical activity, excess weight, heavy alcohol use, smoking, poor sleep and stress. Some cases are caused by other conditions such as kidney disease, sleep apnea, thyroid problems or certain medicines, including some decongestants and anti-inflammatory painkillers.
What lowers blood pressure
- Cut salt. The WHO recommends less than 5 grams of salt (about one teaspoon) a day. Most salt comes from bread, processed meats, ready meals, sauces and restaurant food.
- Eat more plants. The DASH eating pattern — vegetables, fruit, whole grains, beans, nuts and low-fat dairy — lowers blood pressure in weeks.
- Move most days. Aim for at least 150 minutes of moderate activity a week. Brisk walking counts.
- Reach a healthier weight. Even modest weight loss helps.
- Limit alcohol and stop smoking.
- Sleep well and get snoring checked — untreated sleep apnea raises blood pressure.
Medicines
If lifestyle changes are not enough, or your overall risk is high, your clinician may recommend medicine. Common types include ACE inhibitors, angiotensin receptor blockers, calcium channel blockers and thiazide-type diuretics. Many people need two or more at low doses. Keep taking them unless your clinician advises otherwise, even when your readings improve.
Measuring at home
Home monitoring gives a truer picture than an occasional clinic reading. Use a validated upper-arm monitor, sit quietly for five minutes first, and take two readings morning and evening for a week before appointments. Keep them in our private blood pressure log.
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