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Medical News Today: How can you tell when you have high blood pressure?

High blood pressure is called a “silent killer” because it rarely causes symptoms until it severely damages a person’s health.

High blood pressure, or hypertension, affects around 1 in 3 American adults. The current guidelines and definition mean that close to half of all adults in the United States will be diagnosed with the condition.

When a person has high blood pressure, their blood is putting too much pressure on the walls of the arteries as it flows through.

If a person does not receive treatment, hypertension can cause serious health complications, such as heart disease and stroke. Nearly everyone can treat hypertension with lifestyle changes, and some people may also benefit from medication.

In this article, we discuss the myths and facts of high blood pressure symptoms. We also describe high and normal blood pressure readings and complications of high blood pressure.

Fact and fiction

Senior man checking his blood pressure
A person can check their blood pressure to find out what it is.

Some people may believe that if they do not experience symptoms, they have no reason to worry about their blood pressure. Unfortunately, this is not the case.

High blood pressure usually has no symptoms until it causes serious complications. The only way to know a person’s blood pressure is to check it.

Many believe that high blood pressure causes symptoms such as headaches, nervousness, sweating, and facial redness. However, according to the American Heart Association (AHA), hypertension often causes none of these issues.

Symptoms that people often mistakenly attribute to high blood pressure include:

  • Headaches and nosebleeds: Hypertension only causes headaches or nosebleeds when blood pressure is dangerously high, which is known as a hypertensive crisis. This is considered a medical emergency.
  • Dizziness: High blood pressure does not cause dizziness, though some blood pressure lowering medications can make a person feel dizzy.
  • Facial redness: Hypertension does not cause facial flushing, but a person may temporarily experience both high blood pressure and facial flushing from factors such as stress, alcohol, or spicy foods.

People may experience symptoms of high blood pressure when the reading suddenly rises above 180/120 millimeters of mercury (mmHg). This is considered a hypertensive crisis with hypertensive urgency or a hypertensive emergency depending on a person’s other symptoms.

Symptoms of a hypertensive crisis include the following:

  • severe headaches
  • nosebleeds
  • chest pain
  • back pain
  • severe anxiety
  • shortness of breath

Interpreting blood pressure readings

Blood pressure readings contain two numbers expressed as a fraction, such as 120/80 mmHg. Systolic pressure is the first number, and diastolic pressure is the second.

The readings show pressure in different stages:

  • Systolic pressure: This indicates pressure in the arteries when the lower part of the heart beats and the blood pushes harder against the artery wall.
  • Diastolic pressure: This indicates the pressure in the blood vessels between beats.

The current definitions of normal and high blood pressure are:

Blood pressure Systolic mmHg Diastolic mmHg
Normal Less than 120 and Less than 80
Elevated 120–129 and Less than 80
Hypertension stage 1 130–139 or 80–89
Hypertension stage 2 140 or higher or 90 or higher
Hypertensive crisis Higher than 180 and/or Higher than 120

Doctors group blood pressure readings into the following categories:


Doctors define hypotension, or low blood pressure, as pressure below 90/60 mmHg. Extremely low blood pressure can result in less oxygen flowing to organs, which can lead to health complications.


Normal blood pressure for adults refers to readings between 90/60 mmHg and 120/80 mmHg.


Having a systolic pressure reading of 120–130 mmHg and a diastolic pressure reading below 80 mmHg is considered a red flag.

Although these readings are beneath the range for hypertension, they indicate blood pressure that is higher than normal. Elevated blood pressure can rise and become dangerous.

Hypertension stage 1

Hypertension stage 1 includes systolic pressures between 130–139 mmHg and diastolic pressures between 80–89 mmHg.

Hypertension stage 2

This is a more severe form of high blood pressure. Hypertension stage 2 refers to systolic pressures of 140 mmHg or higher, or diastolic pressures of 90 mmHg or higher.

Hypertensive crisis

Hypertensive crisis refers to extremely high blood pressure, of above 180/120 mmHg. Doctors consider this an emergency. It requires immediate medical intervention to prevent damage to blood vessels and major organs.

Symptoms of high blood pressure in pregnancy

Pregnant woman with a headache
Symptoms of high blood pressure during pregnancy can include nausea and headaches.

Hypertension is relatively common during pregnancy, affecting an estimated 6–8 percent of pregnant women ages 20–44 in the U.S.

Hypertension during pregnancy is treatable. Women who have chronic high blood pressure can still have healthy babies, as long as they closely monitor and address their blood pressure throughout their pregnancy.

If a pregnant woman does not receive treatment, however, the uncontrolled high blood pressure can cause serious complications for herself and the baby.

Symptoms and signs of high blood pressure during pregnancy include:

  • headaches
  • nausea
  • vomiting
  • abdominal pain
  • weight gain
  • edema, or swelling
  • signs of kidney problems, such as protein in the urine (proteinuria)
  • shortness of breath
  • dizziness
  • vision problems

Complications of high blood pressure

High blood pressure can cause unnoticeable but progressive damage to the body over the course of several years before a person develops complications.

Some complications of high blood pressure include:

  • sexual dysfunction
  • damage to the arteries and other blood vessels
  • a heart attack
  • heart failure
  • ischemic heart disease
  • microvascular disease
  • an abnormally thickened wall of the left ventricle, which is called left ventricular hypertrophy
  • an ischemic or hemorrhagic stroke
  • an artery aneurysm and rupture
  • vision loss
  • kidney disease, including kidney failure


High blood pressure is a common health condition that can cause serious complications if a person does not receive treatment.

Some people mistakenly believe that hypertension will cause noticeable symptoms, like headaches, nosebleeds, and dizziness. However, these usually do not occur until high blood pressure becomes a medical emergency.

Usually, there are no symptoms, so many people are unaware that they have high blood pressure until serious health complications occur.

The only way to assess blood pressure is to get it checked. It is important to do so regularly, especially for people who have had readings above the normal range.

Women can develop high blood pressure during pregnancy. It may be a good idea for pregnant women to speak to their healthcare providers about ways to prevent or reduce high blood pressure.