MRI (or magnetic resonance imaging) scan is a radiology technique which uses magnetism, radio waves, and a computer to produce images of body structures. MRI scanning is painless and does not involve X-ray radiation. Patients with heart pacemakers, metal implants, or metal chips or clips in or around the eyes cannot be scanned with MRI because of the effect of the magnet.

Hypertension occurs in around 0.2 to 3% of newborns; however, blood pressure is not measured routinely in healthy newborns.[33] Hypertension is more common in high risk newborns. A variety of factors, such as gestational age, postconceptional age and birth weight needs to be taken into account when deciding if a blood pressure is normal in a newborn.[33]
The first chemical for hypertension, sodium thiocyanate, was used in 1900 but had many side effects and was unpopular.[152] Several other agents were developed after the Second World War, the most popular and reasonably effective of which were tetramethylammonium chloride, hexamethonium, hydralazine, and reserpine (derived from the medicinal plant Rauwolfia serpentina). None of these were well tolerated.[159][160] A major breakthrough was achieved with the discovery of the first well-tolerated orally available agents. The first was chlorothiazide, the first thiazide diuretic and developed from the antibiotic sulfanilamide, which became available in 1958.[152][161] Subsequently, beta blockers, calcium channel blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and renin inhibitors were developed as antihypertensive agents.[158]
Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
The best evidence indicates that high blood pressure does not cause headaches or nosebleeds, except in the case of hypertensive crisis, a medical emergency when blood pressure is 180/120 mm Hg or higher. If your blood pressure is unusually high AND you have headache or nosebleed and are feeling unwell, wait five minutes and retest. If your reading remains at 180/120 mm Hg or higher, call 9-1-1.  
Why stress happens and how to manage it Stress is essential for survival; the chemicals it triggers help the body prepare to face danger and cope with difficulty. Long-term stress is linked to various health conditions and can cause physical and psychological symptoms. How is it diagnosed, what types of stress are there, and how is it treated or managed? Read now
High blood pressure is the #2 cause of kidney failure. It accounts for about one-fourth of all cases. High blood pressure can be both a cause of kidney disease and a symptom of kidney disease. When high blood pressure damages your kidneys, they are not able to do all their jobs as well—and one of their jobs is helping your body regulate your blood pressure.
The guidelines, from the American Heart Association (AHA) and the American College of Cardiology (ACC), now define high blood pressure as 130 mm Hg or higher for the systolic blood pressure measurement, or 80 mm Hg or higher for the diastolic blood pressure measurement. (Systolic is the top number, and diastolic is the bottom number, in a blood pressure reading.) Previously, high blood pressure was defined as 140 mm Hg or higher for the systolic measurement and 90 or higher for the diastolic measurement.
Postural hypotension is considered a failure of the cardiovascular system or nervous system to react appropriately to sudden changes. Normally, when you stand up, some blood pools in your lower extremities. Uncorrected, this would cause your blood pressure to fall. But your body normally compensates by sending messages to your heart to beat faster and to your blood vessels to constrict. This offsets the drop in blood pressure. If this does not happen, or happens too slowly, postural hypotension results and can lead to fainting.
Keeping track of your blood pressure is important. Your doctor can help you learn how to check your blood pressure at home. Each time you check your own blood pressure, record your numbers and the date. Send or take the log of your blood pressure readings with you for appointments with your doctor. Return to Screening for reminders on how to prepare for blood pressure testing.
According to guidelines from the American Heart Association (AHA) and the American College of Cardiology (ACC), a reading below 120/80 mm Hg is classified as normal blood pressure. Those with a blood pressure reading anywhere from 120/80 up to 129/80 are classified within a category called elevated blood pressure. Hypertension is defined as a reading of 130/80 or higher.

Certain medications: A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson’s disease; tricyclic antidepressants; erectile dysfunction drugs, particularly in combination with nitroglycerine; narcotics and alcohol. Other prescription and over-the-counter drugs may cause low blood pressure when taken in combination with high blood pressure medications.

^ Aronow WS, Fleg JL, Pepine CJ, Artinian NT, Bakris G, Brown AS, Ferdinand KC, Ann Forciea M, Frishman WH, Jaigobin C, Kostis JB, Mancia G, Oparil S, Ortiz E, Reisin E, Rich MW, Schocken DD, Weber MA, Wesley DJ, Harrington RA, Bates ER, Bhatt DL, Bridges CR, Eisenberg MJ, Ferrari VA, Fisher JD, Gardner TJ, Gentile F, Gilson MF, Hlatky MA, Jacobs AK, Kaul S, Moliterno DJ, Mukherjee D, Rosenson RS, Stein JH, Weitz HH, Wesley DJ (2011). "ACCF/AHA 2011 expert consensus document on hypertension in the elderly: a report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents developed in collaboration with the American Academy of Neurology, American Geriatrics Society, American Society for Preventive Cardiology, American Society of Hypertension, American Society of Nephrology, Association of Black Cardiologists, and European Society of Hypertension". J Am Soc Hypertens. 5 (4): 259–352. doi:10.1016/j.jash.2011.06.001. PMID 21771565.
The cuff is placed around the upper arm and inflated with an air pump to a pressure that blocks the flow of blood in the main artery that travels through the arm. The arm is held at the side of the body at the level of the heart, and the pressure of the cuff is gradually released. As the pressure decreases, a health practitioner listens with a stethoscope over the artery at the front of the elbow or an electronic machine senses the pulsation. The pressure at which the practitioner (or machine) first hears a pulsation from the artery is the systolic pressure (the top number). As the cuff pressure decreases further, the pressure at which the pulsation finally stops is the diastolic pressure (the bottom number).

High blood pressure is the #2 cause of kidney failure. It accounts for about one-fourth of all cases. High blood pressure can be both a cause of kidney disease and a symptom of kidney disease. When high blood pressure damages your kidneys, they are not able to do all their jobs as well—and one of their jobs is helping your body regulate your blood pressure. 

Postural hypotension is considered a failure of the cardiovascular system or nervous system to react appropriately to sudden changes. Normally, when you stand up, some blood pools in your lower extremities. Uncorrected, this would cause your blood pressure to fall. But your body normally compensates by sending messages to your heart to beat faster and to your blood vessels to constrict. This offsets the drop in blood pressure. If this does not happen, or happens too slowly, postural hypotension results and can lead to fainting.
Researchers at the University of Melbourne and Macquarie University have uncovered unusual activity between neurons controlling breathing and blood pressure during the development of essential hypertension. Essential hypertension, which is high blood pressure with no known cause, affects 30% of the global population and is a major contributor to cardiovascular disease.
Low blood pressure is also known as hypotension. This is usually defined in an adult as a systolic recording of less than 90 mmHg, although it has been suggested that for elderly people, below 110 mmHg is a more appropriate definition. Blood pressure and heart rate are controlled by the autonomic nervous system (the nervous system that controls bodily functions that we do not have to think about).                                                                                                                                                                                                
Unchecked, high blood pressure can lead to a myriad of serious health problems, such as heart attacks, strokes, and other forms of heart disease and kidney disease. It is extremely dangerous during pregnancy because it contributes to devastating and even deadly problems for moms and babies. Other impacts of hypertension include vision problems and sexual dysfunction.

African-Americans are at greater risk of developing hypertension than people of other races. African-Americans develop high blood pressure earlier in life and have more difficulty achieving blood pressure goals. Some studies suggest that African-Americans may be more sensitive to salt than other races. For those who are genetically prone to salt sensitivity, a small amount (half-teaspoon) of salt can raise blood pressure by 5 mm Hg. Dietary factors and being overweight can also raise blood pressure.


This study is exploring whether use of losartan, a medicine commonly used to lower blood pressure, is effective at treating abnormal nighttime blood pressure in children and young adults who have sickle cell disease. To participate in this study, you or your child must be 5 to 25 years old and have high blood pressure and a certain type of sickle cell disease: hemoglobin SS or Sβ0 thalassemia. This study is located in Birmingham, Alabama.
Chronic low blood pressure with no symptoms is almost never serious. But health problems can occur when blood pressure drops suddenly and the brain is deprived of an adequate blood supply. This can lead to dizziness or lightheadedness. Sudden drops in blood pressure most commonly occur in someone who's rising from a lying down or sitting position to standing. This kind of low blood pressure is known as postural hypotension or orthostatic hypotension. Another type of low blood pressure can occur when someone stands for a long period of time. This is called neurally mediated hypotension. When it leads to passing out, if is called vasovagal syncope.
Angiotensin receptor blockers prevent the actions of angiotensin II on the arteries. This means the arteries stay more open and blood pressure is lowered. ARBs can take a few weeks to work. Side effects can include dizziness, muscle cramps, insomnia, and elevated potassium levels. As with ACE inhibitors, women who are pregnant, planning to get pregnant, or breastfeeding should not take ARBs.
If diet and exercise are not sufficient to lower blood pressure, the first medications recommended are often diuretics or so-called "water pills." These reduce sodium and fluid levels in the body to lower blood pressure. Taking diuretics means you will urinate more frequently. Sometimes, diuretics deplete potassium levels as well, which can lead to muscle weakness, leg cramps, and tiredness. Other side effects of diuretics can include elevated blood sugars in people with diabetes. Less commonly, erectile dysfunction can occur.
Some women with normal blood pressure develop high blood pressure during pregnancy. As part of your regular prenatal care, your doctor will measure your blood pressure at each visit. If you develop high blood pressure, your doctor will closely monitor you and your baby and provide special care to lower the chance of complications. With such care, most women and babies have good outcomes.
High blood pressure often runs in families. Much of the understanding of the body systems involved in high blood pressure has come from genetic studies. Research has identified many gene variations associated with small increases in the risk of developing high blood pressure. New research suggests that certain DNA changes during fetal development may also lead to the development of high blood pressure later in life.

Although it's most common in older adults, hypertension can also affect children. The normal blood pressure for a child is dependent upon the child's age, gender, and height. Your doctor can tell if your child's blood pressure is abnormal. Children are at higher risk for hypertension if they are overweight, African-American, or if they have a family history of the condition. Children with high blood pressure may benefit from the DASH diet and taking medications. Children with high blood pressure should also maintain a healthy weight and avoid tobacco smoke. 

Blood pressure is given as a reading of two numbers, such as 110/70. The higher number (systolic) is the pressure when the heart beats. The diastolic, or lower number shows the pressure between the heartbeats, while the relaxed heart is refilling with blood. Normal blood pressure readings are lower than 120/80. The cause of most hypertension is unknown. Occasionally, conditions of the kidney or adrenal gland are the cause of high blood pressure.


Not only the degree of obesity is important, but also the manner in which the body accumulates extra fat. Some people gain weight around their belly (central obesity or "apple-shaped" people), while others store fat around their hips and thighs ("pear-shaped" people). "Apple-shaped" people tend to have greater health risks for high blood pressure than "pear-shaped" people.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by a specific blood pressure number. Some individuals routinely may have blood pressure numbers of 90/50 with no symptoms and therefore do not have low blood pressure. However, others who normally have higher blood pressures may develop symptoms of low blood pressure if their blood pressure drops to 100/60.
Optimal blood pressure is less than 120/80 (systolic/diastolic). In healthy people, low blood pressure without any symptoms is not usually a concern and does not need to be treated. But low blood pressure can be a sign of an underlying problem -- especially in the elderly -- where it may cause inadequate blood flow to the heart, brain, and other vital organs.
High blood pressure is classified as either primary (essential) high blood pressure or secondary high blood pressure.[5] About 90–95% of cases are primary, defined as high blood pressure due to nonspecific lifestyle and genetic factors.[5][6] Lifestyle factors that increase the risk include excess salt in the diet, excess body weight, smoking, and alcohol use.[1][5] The remaining 5–10% of cases are categorized as secondary high blood pressure, defined as high blood pressure due to an identifiable cause, such as chronic kidney disease, narrowing of the kidney arteries, an endocrine disorder, or the use of birth control pills.[5] 

Palma Gamiz JL, et al. Iberian Multicenter Imidapril Study on Hypertension: A twelve-week, Multicenter, Randomized, Double-blind, Parallel-Group, Noninferiority Trial of the Antihypertensive Efficacy and Tolerability of Imidapril and Candesartan in Adult Patients With Mild to Moderate Essential Hypertension: the Iberian Multicenter Imidapril Study on Hypertension (IMISH).
Methyldopa, formerly known under the brand name Aldomet, is one of the oldest blood pressure medications still in use. It was first introduced more than 50 years ago. Methyldopa works in the central nervous system to lower blood pressure. While its general use has declined over the years, methyldopa is considered the first-line of treatment for high blood pressure that develops during pregnancy.
The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discovery to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including high blood pressure. Learn about the current and future NHLBI efforts to improve health through research and scientific discovery.

Although a fever technically is any body temperature above the normal of 98.6 F (37 C), in practice, a person is usually not considered to have a significant fever until the temperature is above 100.4 F (38 C). Fever is part of the body's own disease-fighting arsenal; rising body temperatures apparently are capable of killing off many disease-producing organisms.


The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discovery to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including high blood pressure. Learn about the current and future NHLBI efforts to improve health through research and scientific discovery.
Hypertension, the medical term for high blood pressure, is known as "the silent killer." More than 80 million Americans (33%) have high blood pressure, and as many as 16 million of them do not even know they have the condition. If left untreated, high blood pressure greatly increases your risk for heart attack and stroke. Hypertension is projected to increase about 8 percent between 2013 and 2030.
Low blood pressure is diagnosed by a doctor when they check your blood pressure with a sphygmomanometer. For people who experience low blood pressure without other symptoms, it may only require regular monitoring by a doctor during routine exams, and medical treatment may not be necessary. If certain signs suggest an underlying condition, your doctor may recommend one or more of the following tests to diagnose a cause for your hypotension:
Imagine a garden hose hooked up to a spigot. When the hose is flexible and there are no kinks in it, you can turn on the water full blast and it will flow easily through the hose. But if there’s a kink in the hose, the water doesn’t flow as well beyond the kink. And the pressure inside the hose builds up behind the kink. Or imagine there is gunk inside the hose blocking the path of the water. Your arteries are a lot like that garden hose.
*Your diet is an important part of blood pressure control. The Dietary Approaches to Stop Hypertension (DASH) eating plan and limiting sodium (salt) help control blood pressure. Ask your doctor to refer you to a dietitian for specific dietary guidelines. More information is available from the National Heart, Lung and Blood Institute at www.nhlbi.nih.gov or the American Heart Association at www.americanheart.org.*
This study is assessing whether a low-sodium and low-calorie eating pattern, along with aerobic exercise, can improve blood pressure in patients who do not respond to high blood pressure medicines. To participate you must be at least 35 years and have high blood pressure that does not respond to medicines. Please note that this study is in Durham, North Carolina.
If your blood pressure is elevated, your doctor may request you have more readings over the course of a few days or weeks. A hypertension diagnosis is rarely given after just one reading. Your doctor needs to see evidence of a sustained problem. That’s because your environment can contribute to increased blood pressure, such as the stress you may feel by being at the doctor’s office. Also, blood pressure levels change throughout the day.

With age, comes an increased risk for systolic hypertension which can be aggravated by severe atherosclerosis. According to one study, the diuretic chlorthalidone (Hygroton) had significant benefit in elderly patients with systolic hypertension. Along with a diuretic, some calcium channel blockers, ACE inhibitors and angiotensin II receptor blockers may also be good choices. However, beta blockers may not be as effective for hypertension in those over 60; though they may be good choices if co-existing heart disease is present. It also may be preferable in elderly patients to give two high blood pressure medications at a low dose versus one at a higher dose.

Health care providers measure blood pressure with a sphygmomanometer (sfig-mo-muh-NAH-muh-ter), which has a cuff that's wrapped around the upper arm and pumped up to create pressure. When the cuff is inflated, it squeezes a large artery in the arm, stopping the blood flow for a moment. Blood pressure is measured as air is gradually let out of the cuff, which allows blood to flow through the artery again.
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