How common is it?
The South African Demographic and Health Survey (2016) found that almost half of women and men aged 15 and older had high blood pressure. Many didn't know.
Understanding the two numbers
A reading such as 128/82 mmHg has two parts:
- Systolic (top number): the pressure when your heart beats.
- Diastolic (bottom number): the pressure when your heart rests between beats.
Either number being high counts.
What counts as high?
According to the South African hypertension practice guideline:
| Setting | High blood pressure |
|---|---|
| Clinic or rooms | 140/90 mmHg or higher, confirmed on repeated visits |
| Home readings (average) | 135/85 mmHg or higher |
| 24-hour monitor (daytime average) | 135/85 mmHg or higher |
| 24-hour monitor (night-time average) | 120/70 mmHg or higher |
Home and 24-hour thresholds are lower because readings taken at rest, in a familiar setting, tend to be lower than clinic readings.
A note on different guidelines. Some international guidelines use lower thresholds. The 2025 American Heart Association and American College of Cardiology guideline, for example, defines high blood pressure from 130/80 mmHg and recommends a target below 130/80 for most adults. Your doctor will choose the targets that fit your situation.
A single high reading is not a diagnosis. Blood pressure varies with stress, caffeine, pain and activity. Diagnosis normally needs repeated readings, or home or 24-hour monitoring.
Why is it called a "silent" condition?
Most people with high blood pressure feel perfectly well. Headaches and nosebleeds are not reliable signs. The only way to know is to measure.
How to measure your blood pressure at home
Using a validated upper-arm monitor:
- Avoid caffeine, smoking and exercise for 30 minutes before.
- Sit quietly for five minutes, back supported, feet flat, legs uncrossed.
- Rest your arm on a table with the cuff at heart level, on bare skin.
- Use the right cuff size. A cuff that's too small gives falsely high readings.
- Don't talk during the reading.
- Take two readings a minute apart, morning and evening, for about a week, and write them down.
Bring the record, and your device if you can, to your doctor.
What lowers blood pressure?
Lifestyle measures recommended in the South African guideline include:
- Reduce salt. The World Health Organization recommends less than 5 g of salt a day (about one teaspoon), including salt already in bread, stock cubes and processed foods.
- Lose weight if you carry excess weight, particularly around the waist.
- Be active regularly. Aim for 150 to 300 minutes of moderate activity a week.
- Drink alcohol only in moderation, or not at all.
- Stop smoking. Smoking together with high blood pressure greatly raises the risk of heart attack and stroke.
- Sleep well. Short or poor sleep is linked to higher blood pressure.
Many people also need medicine. Treatment targets are usually below 140/90 mmHg, and lower for some higher-risk people. Your doctor will advise you.
When to see a doctor
- Book a check if you haven't had your blood pressure measured in the past year, or if home readings average 135/85 or higher.
- Seek urgent care if a very high reading comes with chest pain, shortness of breath, sudden weakness, confusion, difficulty speaking, a severe headache or changes in vision. Call 10177 or 112.
Frequently asked questions
What is a normal blood pressure?
Clinic readings below 140/90 mmHg are outside the hypertension range. Lower is generally better for long-term heart health, within limits your doctor sets.
Can stress cause high blood pressure?
Stress raises blood pressure temporarily. Long-term stress may contribute through sleep, diet, alcohol and activity habits.
Do I need medication forever?
Not always. Some people can reduce or stop medicines after major lifestyle changes, but only under a doctor's supervision.
Are wrist monitors accurate?
Validated upper-arm monitors are generally preferred.
References
- Seedat YK, Rayner BL, Veriava Y. South African hypertension practice guideline 2014. Cardiovascular Journal of Africa. 2014;25(6):288-294.
- National Department of Health, Stats SA, SAMRC and ICF. South Africa Demographic and Health Survey 2016: Key Findings. https://www.dhsprogram.com/pubs/pdf/DM142/DM142.pdf
- World Health Organization. Sodium reduction fact sheet.
- World Health Organization. Guidelines on physical activity and sedentary behaviour. 2020.
- Jones DW et al. 2025 AHA/ACC guideline for the prevention, detection, evaluation and management of high blood pressure in adults. Hypertension. 2025.
This article is for general educational purposes only, like a health newsletter. It is not medical advice, diagnosis or treatment, and reading it does not create a doctor and patient relationship. Please speak to your own doctor about your situation. In an emergency, call 10177 or 112, or go to your nearest emergency unit.