People sometimes refer to high blood pressure as a “silent killer” because it rarely causes symptoms until it severely damages a person’s health.

About 47% of all adults in the United States have high blood pressure, also known as hypertension, or are taking medications to treat it.

When a person has high blood pressure, their blood puts too much pressure on the walls of the arteries. In time, this can lead to atherosclerosis, which is the term for the arteries becoming thicker and harder. Atherosclerosis increases the risk of stroke and various types of heart disease.

High blood pressure can also be a sign of other problems, such as kidney disease and preeclampsia, which can occur during pregnancy.

For these reasons, it is important for a person to know whether they have high blood pressure.

However, hypertension does not usually cause symptoms. People usually only find out that they have hypertension when a doctor measures their blood pressure or they use an at-home monitor.

In this article, we discuss some myths and facts about high blood pressure symptoms. We also define high, low, and normal blood pressure readings and explain the complications of high blood pressure.

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Some people may believe that if they do not experience symptoms, they do not need to worry about their blood pressure. However, this is not true.

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

Many people believe that high blood pressure causes headaches, nosebleeds, nervousness, sweating, sleeping problems, and facial flushing. According to the American Heart Association (AHA), people often have none of these symptoms.

However, some of these symptoms do have links with high blood pressure. For example:

  • Some blood pressure medications can cause dizziness, but high blood pressure will not.
  • Hypertension does not cause facial flushing, but a person may temporarily experience both high blood pressure and facial flushing due to factors such as stress, alcohol, exposure to heat, or spicy foods.
  • Blood spots in the eyes are more common in people with high blood pressure, but hypertension does not cause them.

When blood pressure is dangerously high, known as a hypertensive crisis, hypertension can cause headaches or nosebleeds. Healthcare professionals define a hypertensive crisis as a blood pressure reading of 180 millimeters of mercury (mm Hg) over 120 mm Hg or higher. It is a medical emergency.

Other symptoms that may occur with a hypertensive crisis include severe anxiety and shortness of breath.

If a person also has chest pain and difficulty breathing, they may be experiencing a heart attack.

Learn how to spot a heart attack and what to do if it happens.

Blood pressure readings contain two numbers, with one number over the other — for example, 120/80 mm Hg. Systolic pressure is the first number, and diastolic pressure is the second.

The readings show pressure at different times:

  • Systolic pressure: This indicates the 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 heart beats.

Doctors regard low, normal, and high blood pressure readings as follows:

Blood pressureSystolic (mm Hg)Diastolic (mm Hg)
low (hypotension)below 90andbelow 60
normalless than 120andless than 80
elevated120–129andless than 80
hypertension stage 1130–139or80–89
hypertension stage 2140 or higheror90 or higher
hypertensive crisishigher than 180and/orhigher than 120

If a person’s blood pressure reading is 120–129 mm Hg over 80 or higher, they should seek medical advice. A doctor will most likely discuss lifestyle measures that can help manage or reduce blood pressure levels.

High blood pressure can cause unnoticeable but progressive damage to the body over several years before complications appear.

Some possible 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

Hypertension is relatively common during pregnancy. It occurs in 1 in every 12–17 pregnancies in those aged 20–44 years in the U.S.

Hypertension during pregnancy is treatable, but a doctor will monitor blood pressure throughout. If a person has persistent high blood pressure or has high blood pressure before pregnancy, they may need additional monitoring and treatment. These measures can help prevent complications for the individual and the fetus.

Symptoms and signs of high blood pressure during pregnancy include:

  • a persistent headache
  • blurry vision, seeing spots, and other vision changes
  • nausea, vomiting, or both
  • edema, or swelling, in the hands and face
  • sudden weight gain
  • shortness of breath

High blood pressure can lead to complications for the individual and the fetus.

For the pregnant person, there is a risk of:

For the fetus, it can result in:

  • preterm birth
  • low birth weight
  • difficulty getting enough oxygen and nutrients, making early delivery necessary

High blood pressure, or hypertension, is a common health condition. Without treatment, it can lead to serious complications.

Hypertension does not usually cause noticeable symptoms. However, headaches, nosebleeds, and dizziness may occur if it becomes a medical emergency.

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

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

High blood pressure is common during pregnancy. A person who is pregnant and has high blood pressure will need additional monitoring to reduce the risk to themself and the developing baby. A doctor may also prescribe medication.

Learn which medications a doctor can prescribe for high blood pressure.