📖 Blood Pressure Guide

What Is Blood Pressure?

Blood pressure is the force that your blood exerts against the walls of your arteries as your heart pumps it around your body. It is measured in millimetres of mercury (mmHg) and recorded as two numbers separated by a slash — for example, 120/80 mmHg.

Pulse rate (heart rate) is the number of times your heart beats per minute. A normal resting pulse for adults is 60–100 bpm. Lower resting pulse often indicates better cardiovascular fitness.

Blood pressure classification is based on whichever number — systolic or diastolic — falls into the higher category. For example, a reading of 135/75 mmHg falls into Stage 1 Hypertension because the systolic value (135) qualifies, even though the diastolic (75) is in the Normal range.

Blood Pressure Categories (WHO / ACC/AHA Guidelines)

The following categories are based on guidelines from the World Health Organization (WHO) and the American College of Cardiology / American Heart Association (ACC/AHA). Your doctor may use slightly different thresholds depending on your age, health history, and country.

🔵 Low Blood Pressure (Hypotension) — below 90/60 mmHg

Blood pressure below the normal range. Occasional low readings may be harmless and some people naturally run low. However, chronic hypotension can cause dizziness, lightheadedness, fainting, fatigue, and blurred vision. Common causes include dehydration, prolonged bed rest, certain medications (diuretics, antidepressants, beta-blockers), heart problems, and endocrine disorders. Consult your doctor if you frequently experience symptoms.

🟢 Normal Blood Pressure — below 120/80 mmHg

Optimal blood pressure range associated with the lowest risk of cardiovascular disease. Maintaining this range through regular exercise, a balanced diet low in sodium, and healthy lifestyle habits is the goal. Continue regular monitoring to stay aware of any changes over time.

🟡 Elevated Blood Pressure — 120–129 / below 80 mmHg

Elevated blood pressure is above normal but not yet classified as hypertension. People with consistently elevated readings are at increased risk of developing Stage 1 hypertension and cardiovascular disease. This is a critical window for lifestyle intervention — diet changes, exercise, stress management, and reducing sodium intake can often restore normal levels without medication.

🟠 High Blood Pressure Stage 1 — 130–139 / 80–89 mmHg

Stage 1 hypertension indicates consistently elevated pressure that, without treatment, significantly increases the risk of heart attack, stroke, and kidney damage over time. A doctor may recommend lifestyle changes and, depending on overall cardiovascular risk, antihypertensive medication. Home monitoring is especially important at this stage to track whether interventions are working.

🔴 High Blood Pressure Stage 2 — 140/90 mmHg or higher

Stage 2 hypertension is a serious condition. At these levels, the risk of heart attack, stroke, heart failure, and kidney disease is significantly elevated. A combination of lifestyle changes and antihypertensive medication is typically required. Regular monitoring, medication adherence, and close communication with your doctor are essential.

🚨 Hypertensive Crisis — 180/120 mmHg or higher

A hypertensive crisis requires immediate medical attention. At these levels, blood pressure can cause acute organ damage including stroke, heart attack, kidney failure, and vision loss. Symptoms may include severe headache, chest pain, shortness of breath, vision problems, nausea, or no symptoms at all (silent crisis). If you record a reading of 180/120 or higher, wait 5 minutes and measure again. If still that high, call emergency services immediately.

How to Measure Blood Pressure Correctly at Home

The accuracy of home blood pressure measurements depends heavily on technique. Following these guidelines will give you the most reliable readings.

Before measuring

• Avoid caffeine (coffee, tea, energy drinks) for at least 30 minutes before measuring.
• Do not smoke or exercise for at least 30 minutes before measuring.
• Empty your bladder — a full bladder can raise blood pressure by 10–15 mmHg.
• Sit quietly and rest for at least 5 minutes before taking the reading.
• Avoid measuring if you are stressed, anxious, or in pain — wait until you feel calm.

Body position

• Sit in a chair with your back fully supported — do not lean forward.
• Keep your feet flat on the floor, not crossed.
• Rest your arm on a flat surface (table or armrest) with the cuff at heart level.
• Do not talk during the measurement.
• Keep your arm relaxed — tensing muscles can raise the reading.

Taking the reading

• Apply the cuff directly to your skin, not over clothing.
• Position the cuff so the bottom edge is about 2 cm (one finger-width) above your elbow.
• Take two or three readings one minute apart and record the average — single readings can be misleading.
• Measure at the same times each day, ideally morning and evening, for consistent data.
• Morning readings: after waking, before eating, before taking medication, after at least 5 minutes of rest.
• Evening readings: before dinner and before any evening medication.

Consistency

• Always use the same arm (the arm that gives higher readings, if there is a difference).
• Keep a diary or use Blood Pressure Diary app to record all your readings over time.
• Share your home reading log with your doctor — it is far more valuable than a single clinic reading.

Understanding White Coat Hypertension

White coat hypertension is a well-documented phenomenon where blood pressure is elevated when measured in a clinical setting (by a doctor or nurse) but is normal when measured at home. This is caused by the stress or anxiety associated with being at a medical facility. It affects an estimated 15–30% of people diagnosed with high blood pressure in clinical settings.

Home monitoring with Blood Pressure Diary helps identify white coat hypertension by providing a large sample of readings taken in your natural environment. If your home readings are consistently normal but clinic readings are high, discuss this with your doctor — they may recommend ambulatory blood pressure monitoring (ABPM) for a definitive assessment.

The opposite also exists: masked hypertension, where readings appear normal at the clinic but are elevated at home. This is why home monitoring is considered a valuable complement to clinical measurements.

Lifestyle Changes That Lower Blood Pressure

Lifestyle modification is the first-line recommendation for elevated blood pressure and Stage 1 hypertension. Even with Stage 2, lifestyle changes enhance the effectiveness of medication. The following measures are supported by strong clinical evidence:

• Reduce sodium: Limit sodium to less than 2,300 mg per day (about 1 teaspoon of salt). For those with hypertension, the target is ideally below 1,500 mg. Read food labels — processed foods, bread, and canned goods are major hidden sources of sodium.
• Follow the DASH diet: The Dietary Approaches to Stop Hypertension (DASH) diet is specifically designed to lower blood pressure. It emphasises fruits, vegetables, whole grains, lean proteins, and low-fat dairy while limiting saturated fat, red meat, and added sugars.
• Exercise regularly: Moderate aerobic exercise — brisk walking, cycling, swimming — for at least 150 minutes per week (30 minutes, 5 days a week) can lower systolic pressure by 5–8 mmHg.
• Maintain a healthy weight: Every 1 kg (2.2 lb) of weight lost can reduce systolic pressure by approximately 1 mmHg. Even modest weight loss of 5–10% can make a clinically significant difference.
• Limit alcohol: No more than one standard drink per day for women and two for men. Higher intake raises blood pressure and reduces the effectiveness of antihypertensive medication.
• Quit smoking: Tobacco use raises blood pressure acutely and causes cumulative damage to blood vessel walls. Quitting reduces cardiovascular risk substantially within months.
• Reduce stress: Chronic stress contributes to sustained elevated blood pressure. Techniques such as mindfulness meditation, deep breathing exercises, yoga, and adequate sleep (7–9 hours per night) all help.
• Limit caffeine: Caffeine causes a short-term spike in blood pressure. If you are sensitive to caffeine, reducing intake may help maintain lower average readings.
• Take medications consistently: If prescribed antihypertensive medication, take it exactly as directed, at the same time each day. Never stop or adjust medication without consulting your doctor.

Pulse Pressure and Mean Arterial Pressure

Pulse pressure

Pulse pressure is the difference between systolic and diastolic blood pressure. For example, a reading of 120/80 mmHg has a pulse pressure of 40 mmHg. A normal pulse pressure is between 40 and 60 mmHg.

A wide pulse pressure (above 60 mmHg) in older adults may indicate arterial stiffness — reduced elasticity of the large arteries — and is associated with increased cardiovascular risk. A narrow pulse pressure (below 25 mmHg) may indicate reduced cardiac output and can be seen in conditions such as heart failure or aortic stenosis.

Mean arterial pressure (MAP)

Mean arterial pressure is the average pressure throughout one cardiac cycle. It is calculated as: MAP = Diastolic + (Pulse Pressure / 3). A normal MAP is between 70 and 100 mmHg. A MAP below 60 mmHg indicates inadequate organ perfusion and is a medical emergency.

Blood Pressure and Age

Blood pressure naturally tends to increase with age. Systolic pressure rises steadily throughout adulthood due to the gradual stiffening of arteries. Diastolic pressure typically rises until around age 50–55, then gradually declines. This is why isolated systolic hypertension (high systolic, normal diastolic) is more common in older adults.

For people aged 65 and over, international guidelines generally recommend a target systolic blood pressure of less than 130–140 mmHg, though targets should be individualised based on frailty, comorbidities, and medication tolerance.

Blood Pressure Diary includes an optional age-adjustment feature that modifies category thresholds for users over 60, helping to provide more appropriate assessments for older users. You can set your age in the app's Statistics or Info section.

Blood Pressure During Pregnancy

Blood pressure monitoring is particularly important during pregnancy. Blood pressure normally decreases in the first and second trimesters and then rises again in the third. Hypertension in pregnancy (defined as blood pressure ≥ 140/90 mmHg) is associated with serious complications including pre-eclampsia and eclampsia.

Pregnant women with hypertension or at risk of pre-eclampsia are often advised to monitor blood pressure at home. If you are pregnant and consistently recording elevated readings, contact your midwife or obstetrician promptly.

Note: Blood Pressure Diary's category thresholds follow standard adult guidelines and are not specifically tailored for pregnancy. Consult your doctor for pregnancy-specific blood pressure targets.

When to Seek Medical Help

Contact your doctor if you consistently record blood pressure readings above 130/80 mmHg over several days or weeks, even without symptoms. Also consult your doctor if you are taking antihypertensive medication but your readings are not reaching your target range.

Seek emergency medical attention immediately if:

• Your blood pressure reading is 180/120 mmHg or higher on repeated measurement.
• You experience a sudden, severe headache unlike any you have had before.
• You have chest pain, tightness, or pressure.
• You feel sudden shortness of breath or difficulty breathing.
• You experience sudden vision changes, blurred vision, or vision loss.
• You have numbness or weakness in your face, arm, or leg, especially on one side (possible stroke — call emergency services immediately).
• You feel sudden confusion, trouble speaking, or difficulty understanding speech.
• You experience severe nausea or vomiting together with high blood pressure.