High blood pressure almost never announces itself, which is why the only reliable way to know you have it is to measure it. Most people with hypertension feel nothing at all. It is diagnosed at 140/90 mmHg or higher, confirmed on two different days, and left untreated it damages the kidneys, heart and brain silently over years.

Living in the Gulf adds a second question on top of that one. Heat and reduced fluid intake change how some blood pressure medicines behave, particularly diuretics, and a hot season is exactly when people are least likely to connect feeling dizzy with the tablet they have taken for years.

Key takeaways

  • It is usually symptomless. WHO states that most people with hypertension do not feel any symptoms, and that checking is the only way to know.
  • The scale of the gap is enormous. An estimated 600 million adults with hypertension, 44% of them, are unaware they have it, and only about 23% have it under control.
  • Diagnosis is 140/90 mmHg or higher, measured on two different days.
  • 180/120 mmHg with symptoms is an emergency. Severe headache, chest pain, vision changes or an abnormal heart rhythm at that level means seek care immediately.
  • Diuretics plus heat needs planning. They cause fluid and electrolyte loss by design, and reduced thirst sensation can hide dehydration.
  • Air pollution is the most significant environmental risk factor for hypertension, which matters in a region with frequent dust episodes.
  • Never stop a blood pressure medicine because you feel well. Feeling well is the normal state of treated hypertension, not evidence you no longer need it.

What do the numbers actually mean?

Blood pressure is written as two numbers, and hypertension is diagnosed at 140/90 mmHg or above on two separate days.

The first, systolic, number is the pressure in your blood vessels when the heart contracts. The second, diastolic, is the pressure when the heart rests between beats. WHO’s definition is specific about the repetition: hypertension is diagnosed if, measured on two different days, systolic readings on both days are 140 mmHg or higher, and/or diastolic readings on both days are 90 mmHg or higher.

That “two different days” detail matters more than people realise. A single high reading in a clinic, after rushing there through traffic, is not a diagnosis. It is a reason to measure again properly.

Home monitors are useful and widely sold, but WHO makes a point worth repeating: although you can measure your own blood pressure with an automated device, an evaluation by a health professional matters for assessing your overall risk and any associated conditions. The number is one input, not the whole picture.

Why does it matter if I feel completely fine?

Because feeling fine is the normal experience of high blood pressure, right up until the damage shows.

This is the single most important thing to understand about the condition. Most people with hypertension do not feel any symptoms. The pressure is doing its work on the arteries, kidneys, heart and brain regardless of how you feel, and if it is not treated it can cause kidney disease, heart disease and stroke.

The global numbers make the point starkly. Around 600 million adults with hypertension, roughly 44%, do not know they have it. Of everyone who has it, only about 23% have it under control.

The same logic explains why people stop their medication and why that is a mistake. The tablet is what is keeping the number down. Feeling well on treatment is the treatment working, not a sign it is no longer needed.

When is a blood pressure reading an emergency?

When it reaches roughly 180/120 mmHg or higher and you have symptoms with it. Seek care immediately, do not wait for an appointment.

The symptoms WHO lists at that level include:

  • severe headaches
  • chest pain
  • vision changes
  • abnormal heart rhythm

Very high blood pressure can also cause blurred vision and other symptoms below that threshold. The rule of thumb is that hypertension is a condition you manage over months, except when it is not, and the combination of a very high reading with any of those symptoms is the exception.

How does the heat affect my blood pressure medication?

Mostly through fluid balance, and diuretics are the clearest case.

Diuretics such as indapamide, hydrochlorothiazide and furosemide work by increasing fluid and salt loss. That is the mechanism, not a side effect. Add a climate where you lose more fluid through sweat and may drink less than you think, and the same dose can tip into dehydration and electrolyte imbalance. NHS Specialist Pharmacy Service guidance notes that reduced thirst sensation can increase the dehydration risk further, which is why it is easy to miss.

The practical signs to take seriously in summer are dizziness on standing, unusual tiredness, muscle cramps, confusion, and passing much less urine than normal.

Other blood pressure medicines are less directly affected but sit in the same picture. Dehydration lowers blood volume, and a dose calibrated in winter can produce more of a drop than intended in August. That does not mean adjusting it yourself. It means mentioning the season at your review, and reporting dizziness rather than tolerating it.

There is a storage dimension too. Most medicines are licensed for storage below 25°C, and that is easily exceeded here, which we cover in storing medicine in a Gulf summer.

Does dust and air pollution really affect blood pressure?

WHO names air pollution as the most significant environmental risk factor for hypertension and associated diseases.

That is a notable statement for this region. Sand and dust storms raise particulate matter concentrations, and WHO describes them as a growing public health concern mainly for respiratory and cardiovascular diseases. The cardiovascular half of that sentence is easy to skip over.

It does not mean a dust episode will spike your reading in a way you can feel. It means the environmental exposure is part of the long-run risk picture alongside diet, weight, activity, alcohol and tobacco, and it is one more reason to keep the modifiable risks in hand. We cover the respiratory side in allergy in the UAE.

What can I change without medication?

Diet, salt, weight, activity, alcohol and tobacco, and for some people that is enough on its own.

WHO’s modifiable risk factors are unhealthy diet, especially excessive salt, along with saturated and trans fats and low fruit and vegetable intake, physical inactivity, tobacco and alcohol, and being overweight or obese. Lifestyle change can lower blood pressure, though some people will still need medicine.

Salt deserves the most attention here, because it is the easiest to underestimate. Most dietary salt is not what you add at the table; it is already in bread, restaurant food, processed meat, sauces and snacks.

The non-modifiable factors are worth knowing so you can judge your own risk: family history, age over 65, and co-existing conditions such as diabetes or kidney disease. If several apply to you, that is an argument for checking your blood pressure regularly rather than for fatalism.

What about Ramadan?

Fasting changes when you can take a blood pressure tablet, and for diuretics it also changes the fluid picture. Both are worth planning before Ramadan starts.

Most blood pressure medicines can be re-timed to suhoor or iftar, but that is a prescriber’s decision, and the interaction between a re-timed diuretic and a full day without fluid is exactly the sort of thing to raise in advance rather than discover. We cover this in Ramadan and your medication.

Do and don’t

Do:

  • Get your blood pressure measured even if you feel completely well.
  • Confirm a high reading on a second day before concluding anything.
  • Report dizziness, cramps or unusual tiredness in hot weather.
  • Keep fluid intake up, particularly if you take a diuretic.
  • Mention the season and any planned fasting at your medication review.
  • Seek care immediately for a very high reading with symptoms.

Don’t:

  • Don’t stop a blood pressure medicine because you feel fine.
  • Don’t adjust a diuretic dose yourself in summer.
  • Don’t rely on a single reading, high or low.
  • Don’t assume no symptoms means no problem.
  • Don’t treat a home monitor as a replacement for a clinical assessment.

Frequently asked questions

Can I check my own blood pressure at home? Yes, and automated devices are widely available. WHO’s caveat is that a health professional’s evaluation still matters, because assessing risk means looking at more than the number. Home readings are most useful as a series over time rather than as single measurements.

Will my dose need changing in summer? Possibly, and that is a question for your prescriber rather than a change to make yourself. The relevant symptoms to report are dizziness on standing, faintness and unusual tiredness during hot months.

Is one high reading enough to diagnose hypertension? No. The definition requires raised readings on two different days, which is specifically designed to exclude one-off spikes from stress, rushing or a badly-fitted cuff.

Where to go next

The heart and blood pressure category lists what is stocked here, our largest category. The hypertension page approaches it from the diagnosis, and the ingredients index maps each active ingredient to the brands containing it, which is useful if you are matching a medicine you started in another country.

MedicForce option: our catalogue lists blood pressure medicines by active ingredient, so you can identify the equivalent of a brand prescribed elsewhere.