High Blood Pressure: The Condition With No Symptoms

The nurse wraps the cuff around your arm and the machine hums. Two numbers appear on the screen. She records them on your card, advises you to keep an eye on it, and calls the next patient.

Nobody explains what the numbers actually represent. You do not ask, because you feel perfectly well, and because feeling well is what most of us rely on to decide whether we are healthy.

That single assumption is what makes high blood pressure so dangerous. It is a condition with no feeling at all, right up until the day it causes a stroke.

How common this is, and how quietly it hides

The National Health and Morbidity Survey 2023, run by Malaysia’s Institute for Public Health, found that 29.2 percent of adults have hypertension, which is roughly one in three of us. That is the medical name for persistently high blood pressure.

The more telling figure is the split. Of that group, 17.3 percent knew they had it. The remaining 11.9 percent did not, and only discovered it when the survey measured them directly. Almost four in ten people with high blood pressure in Malaysia are walking around unaware of it, and the largest share of those unaware were aged between 18 and 39.

The same survey asked people why they had never been screened. The most common answers were that they felt healthy and that they had no symptoms. Both answers are fair, but neither of them works for this one disease.

What the two numbers actually mean

Blood pressure is written as one number over another, such as 128 over 78. It is measured in millimetres of mercury, shortened to mmHg.

• The top number is the systolic pressure. It is the pressure inside your arteries at the instant your heart contracts and pushes blood outward.
• The bottom number is the diastolic pressure. It is the pressure remaining inside your arteries while the heart relaxes and refills between beats.

Think of a garden hose. The systolic number is the surge when you turn the tap fully open. The diastolic number is the pressure still sitting inside the hose afterwards. Both numbers matter, and either one being excessively high is a problem on its own.

The Malaysian thresholds

The Ministry of Health clinical practice guideline on the management of hypertension defines hypertension as a persistent systolic pressure of 140 mmHg or higher, or a persistent diastolic pressure of 90 mmHg or higher, or both.

The word persistent is doing important work in that sentence. A single high reading on one bad afternoon is not a diagnosis, it is simply a reason to measure again.

Reading	What the Malaysian guideline calls it	What it means for you
Below 120 over 85	Normal range	Keep doing what you are doing, and keep checking.
120 to 139, or 85 to 89	At risk blood pressure	Lifestyle changes matter now, and some high-risk people are treated at this level.
140 over 90 or above, persistently	Hypertension	This requires medical assessment and, for most people, treatment.

Your personal target may be lower than 140 over 90. The Malaysian guideline states plainly that the target depends on the individual patient, and that the decision to begin medication is based on your overall cardiovascular risk rather than on the blood pressure number alone.

People with diabetes are the clearest example. Malaysia’s clinical practice guideline on ischaemic stroke sets their target at a systolic pressure below 130 and a diastolic pressure below 80, and lower still if they tolerate it. A reading that is fine in one person is not fine in another.

Why feeling fine is the entire problem

Very high blood pressure can occasionally cause headaches, nosebleeds or blurred vision. Ordinary high blood pressure, the kind that quietly damages one in three Malaysian adults, causes nothing at all.

Meanwhile the pressure continues working on your arteries, and the damage accumulates over years. It concentrates in four places in particular.

• Your heart. The heart muscle must pump against greater resistance, so it thickens and stiffens. Eventually it struggles to fill properly.
• Your brain. High blood pressure is the most common risk factor for stroke in Malaysia, according to the national stroke guideline.
• Your kidneys. The filters inside them are delicate blood vessels, and pressure destroys them gradually and silently.
• Your eyes. The small vessels in the retina can be damaged, which is why an eye examination occasionally reveals hypertension first.

The kidney damage is worth pausing on, because it is a mirror image of the same trap. Kidneys also fail without producing symptoms, which is why we call them the silent organs. Two silent conditions, feeding each other, and neither one announces itself.

How to measure your blood pressure at home

Home measurement is valuable, and Malaysia’s stroke guideline recommends self-monitoring for everyone with hypertension. The hypertension guideline prefers validated electronic machines over the old mercury ones.

The National Health and Morbidity Survey 2023 found that 44 percent of Malaysians who know they have hypertension own a device at home, and that 89 percent of those owners use it at least once a day. That is encouraging, although a blood pressure reading is easy to take and remarkably easy to take incorrectly.

Before you measure

• Avoid coffee, tea, smoking and exercise for 30 minutes beforehand. Each of them pushes the reading up for a while.
• Empty your bladder first. A full bladder can add several points to your systolic number.
• Sit quietly for five minutes before you press the button. This is the step almost everybody skips, and it matters more than any of the others.

While you measure

• Sit on a chair with your back supported and both feet flat on the floor. Do not cross your legs, and do not sit on the edge of a bed.
• Rest your arm on a table so the cuff sits level with your heart. An arm hanging downward produces a falsely elevated reading.
• Put the cuff on a bare upper arm, not over a sleeve. Use an upper-arm machine rather than a wrist device, and check that the cuff size fits your arm.
• Do not talk, and do not look at your phone. Talking during a measurement raises the number.
• Take two or three readings, one minute apart, and record the average. A single reading tells you very little on its own.

Building a record your doctor can use

• Measure in the morning before your medication, and again in the evening. Do this for about a week before a clinic appointment.
• Write down every reading, including the ones you dislike. Deleting the high numbers defeats the purpose of measuring.
• Bring the record, or the machine itself, to your appointment. A week of home readings tells your doctor far more than one clinic reading.
• Do not adjust your own medication based on a home reading. Bring the numbers to your doctor and let them make that decision.

White coat hypertension and masked hypertension

Blood pressure is not a fixed property like your height, because it fluctuates all day long, and it responds to where you are and how you feel.

That produces two patterns worth understanding, and they point in opposite directions.

Pattern	In the clinic	At home	Why it matters
White coat hypertension	High	Normal	You may be labelled and medicated for a problem you do not actually have.
Masked hypertension	Normal	High	You are reassured, and the damage continues undetected.

Masked hypertension is the more dangerous of the two, precisely because it is invisible. The clinic reading is reassuring, so nothing is done, and the arteries continue absorbing the pressure. This is the strongest single argument for measuring at home, rather than relying on one reading taken twice a year while you are nervous.

If your home readings and your clinic readings disagree consistently, that disagreement is itself a medical finding. Tell your doctor about it, and bring the numbers.

Salt, and where it is actually hiding

Salt raises blood pressure, and that is not seriously disputed. Reducing it is one of the few dietary changes with a direct, measurable effect on the reading.

The World Health Organization recommends that adults consume less than 2,000 mg of sodium a day. That works out at roughly 5 g of salt, which is about one level teaspoon in total for the whole day. Malaysia uses the same figure.

Most of the salt we eat never originates from the salt shaker. It is already inside the food before it reaches the table.

• Sauces and seasonings. Soy sauce, oyster sauce, fish sauce, chilli sauce and stock cubes are extremely concentrated sources of sodium.
• Preserved and dried foods. Salted fish, shrimp paste, fermented fish sauces, salted eggs and preserved vegetables carry very large amounts.
• Instant noodles and packet soups. A single seasoning sachet can approach an entire day’s allowance.
• Snacks and crackers. Prawn crackers, nuts and crisps add sodium quietly, between meals.
• Restaurant and hawker food. You cannot see how much has gone in, and it is usually more than you would add at home.

The practical approach is not to give any of this up. It is to eat it less often, ask for less sauce where you can, and taste food before you season it. Our guide to how much salt, sugar and fat is too much goes through the numbers in detail.

One important caution. Salt substitutes often replace sodium with potassium, and potassium is dangerous for people with kidney disease or those taking certain blood pressure medicines. Ask your doctor or pharmacist before switching.

What actually lowers blood pressure

These changes are not a substitute for medication when medication is needed. They do make a real difference, and they make the medication work better.

• Lose excess weight, especially around the waist. Losing weight is one of the surest ways to bring the number down.
• Exercise for at least 30 minutes a day, or 150 minutes a week. This is the level Malaysia’s stroke guideline recommends, and brisk walking counts.
• Follow an eating pattern built around vegetables, fruit and wholegrains. The DASH eating plan, which the Malaysian guideline names specifically for lowering blood pressure, is exactly this.
• Reduce the salt, using the list above as a starting point. Lowering sodium reduces pressure within weeks, not years.
• Limit alcohol, and stop smoking. Malaysia’s stroke guideline advises against heavy drinking, and smoking harms the same arteries from a different direction.
• Get enough sleep. Short sleep is linked with higher blood pressure, and two in five Malaysian adults sleep less than seven hours a night.
• Have your blood sugar and cholesterol checked at the same time. These conditions cluster together, and diabetes multiplies the damage that pressure does to your blood vessels.

About the medication

Only 48 percent of Malaysians who know they have hypertension have it under control, according to the National Health and Morbidity Survey 2023. That is despite 91 percent of them taking medication. The gap between taking tablets and reaching the target is wide.

For newly diagnosed, uncomplicated hypertension, the Malaysian guideline lists five first-line drug classes: ACE inhibitors, angiotensin receptor blockers, calcium channel blockers, diuretics and beta blockers. Many people eventually need two or more of them together, and needing a second tablet is not a sign of failure. It is normal, and the guideline expects it.

Three things are worth understanding about these medicines.

• They control the pressure. They do not cure it. Your reading is normal because you are taking them, not as an alternative to taking them.
• Stopping because you feel fine is the most common mistake. You felt fine when your pressure was 170 as well. Feeling is not a measurement.
• Side effects are worth reporting, not enduring in silence. A persistent dry cough from an ACE inhibitor, for example, is well recognised, and your doctor can usually switch you to something else.

If your pressure stays above target despite three medicines, including a diuretic, the guideline calls that resistant hypertension. It is a recognised situation with its own approach, and it means your doctor needs to look harder, not that you have failed.

The number is the only symptom you get

High blood pressure gives you no warning, no pain and no hint that anything is wrong. The only symptom it produces is a number on a machine, and you have to go and look for that number deliberately.

So go and look. Have it measured at your next visit to any clinic, even when nothing hurts. If it is high, measure it properly at home for a week and take the record to your doctor.

It is a small, dull, unglamorous habit, and it prevents strokes. You can read more in our heart health section.