High blood pressure
High blood pressure usually has no symptoms, but over time it damages the heart, brain and kidneys. This page explains how it is measured, what the cut-offs are in different sources, and what helps.
What is high blood pressure?
Blood pressure is the force of the blood against the walls of the blood vessels as it circulates. If this force is constantly too high, we call it high blood pressure or hypertension. A blood pressure reading has two numbers: the upper number (when the heart contracts) and the lower number (when the heart rests between beats).
Untreated high blood pressure puts strain on the blood vessels, heart, brain, kidneys and eyes, and raises the risk of heart attack, stroke, heart failure, kidney disease and dementia.
Symptoms
There are usually no symptoms. That is why many people do not know they have high blood pressure. In a few cases headache, blurred vision or chest pain may occur. The only reliable way to know is to measure. The NHS source recommends that people aged 40 and over who have not had it measured for more than 5 years have their blood pressure checked.
Cut-offs for high blood pressure
The sources do not agree on the cut-off, and you should know this:
- NHS (UK): 140/90 or higher in the clinic and 135/85 or higher at home counts as high.
- CDC (US): high blood pressure means a persistent 130/80 or higher. Stage 1 is 130 to 139 or 80 to 89, and stage 2 is 140 or 90 and above.
Neither source gives a separate cut-off for age or pregnancy. The doctor sets the target for each patient, taking into account age, diabetes, kidney disease, pregnancy and other circumstances. So do not take a number you read online as your own target.
How is it diagnosed?
Diagnosis is by measuring blood pressure. Because the number changes through the day, according to the CDC the doctor may measure several times and at more than one visit, or ask for home monitoring with a validated device. The NHS also mentions home monitoring over several days or a 24-hour monitor. Home measurement is covered in the guide “Measuring blood sugar and blood pressure at home”.
Treatment and management
Based on the sources:
- Changes to daily habits: less salt, a healthy balanced diet, regular physical activity (the CDC says about 30 minutes a day on 5 days a week; the NHS says at least 150 minutes a week), reaching a suitable weight, stopping smoking, cutting down on alcohol and caffeine, and managing stress. Even a small drop in blood pressure lowers the risk.
- The DASH diet: a diet full of vegetables, fruit, whole grains and low-fat dairy, and low in salt and sweet foods. The NHLBI suggests at most 2,300 mg of sodium a day, and 1,500 mg has a greater effect. The World Health Organization also recommends less than 5 grams of salt a day.
- Medicine: the NHS says the doctor prescribes medicine if blood pressure is very high, the risk of a heart attack or stroke is high, or it does not come down with changes to daily habits. The type of medicine depends on the reading, age and circumstances, and some patients need more than one. Do not stop the blood pressure tablet or change the amount yourself, even if the reading has become normal.
Follow-up and self-care
- Measure your blood pressure as the doctor plans and write the readings down.
- Tell the doctor about all your medicines and supplements.
- Have tests such as kidney function, blood sugar and blood fats on time, since high blood pressure is linked to them.
- If you are pregnant or planning a pregnancy, let the doctor know.
When should you call?
Call 115 (the emergency number in Iran) at once if you have sudden chest pain or pressure that does not go away, the pain spreads to the arm, neck, jaw, stomach or back, or the pain comes with sweating, nausea, light-headedness or shortness of breath. Weakness or numbness on one side of the body, a drooping face, difficulty speaking, sudden blurred vision or a sudden severe headache are also emergencies. The CDC source says blood pressure above 180 and/or 120 together with emergency symptoms (chest pain, shortness of breath, numbness, weakness, change in vision, difficulty speaking) is an emergency. Do not drive yourself.
If your blood pressure is above 180 and/or 120 but you have no symptoms, the CDC says to contact the doctor straight away.
Talk to the doctor if you have frequent headaches or blurred vision, your blood pressure is not controlled with treatment, or you have become dizzy and weak after taking a medicine.
Every patient’s treatment plan is different; ask the doctor about your own situation.
Frequently asked questions
My blood pressure is high but I have no symptoms. Does it still need treatment?
Yes, it needs to be assessed. The NHS and CDC sources say high blood pressure usually has no symptoms and only measurement shows it. The doctor decides on treatment, or whether it is needed, from several readings and your circumstances.
What is a normal blood pressure?
The sources do not give one cut-off. The NHS counts 140 over 90 or higher in the clinic (and 135 over 85 at home) as high; the CDC, following the US guideline, counts 130 over 80 and above as high. The doctor sets the right target for you, taking into account age, diabetes, kidney disease and pregnancy.
If my blood pressure becomes normal, can I stop the medicine?
Not without the doctor. A normal reading may be the result of that very treatment. Any change to medicine has to come from the doctor, based on your measurements.
My blood pressure is higher in the clinic than at home. Why?
Blood pressure changes through the day. For this reason the doctor may ask for several readings, or for home or 24-hour monitoring. Write down your home readings and bring them with you.
How much should I cut down on salt?
The World Health Organization recommends adults have less than 5 grams of salt a day. The NHLBI source sets a sodium goal of 2,300 mg a day, and says 1,500 mg lowers blood pressure even more. If you have kidney disease, heart disease or another condition, talk to the doctor.