Definition
High blood pressure is a common condition in which the force of the blood against your artery walls is high enough that it may eventually cause health problems, such as heart disease.
Blood pressure is determined by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure.
You can have high blood pressure (hypertension) for years without any symptoms. Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke.
High blood pressure typically develops over many years, and it affects nearly everyone eventually. Fortunately, high blood pressure can be easily detected. And once you know you have high blood pressure, you can work with your doctor to control it.
Causes
There are two types of high blood pressure.
Primary (essential) hypertension
For most adults, there’s no identifiable cause of high blood pressure. This type of high blood pressure, called essential hypertension or primary hypertension, tends to develop gradually over many years.
Secondary hypertension
Some people have high blood pressure caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions and medications can lead to secondary hypertension, including:
• Kidney problems
• Adrenal gland tumors
• Certain defects in blood vessels you’re born with (congenital)
• Certain medications, such as birth control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs
• Illegal drugs, such as cocaine and amphetamines
Low blood pressure (hypotension)
Definition
Low blood pressure, also called hypotension, would seem to be something to strive for. However, for many people, low blood pressure can cause symptoms of dizziness and fainting. In severe cases, low blood pressure can be life-threatening.
Although blood pressure varies from person to person, a blood pressure reading of 90 millimeters of mercury (mm Hg) or less systolic blood pressure (the top number in a blood pressure reading) or 60 mm Hg or less diastolic blood pressure (the bottom number) is generally considered low blood pressure.
The causes of low blood pressure can range from dehydration to serious medical or surgical disorders. Low blood pressure is treatable, but it’s important to find out what’s causing your condition so that it can be properly treated.
Causes
Blood pressure is a measurement of the pressure in your arteries during the active and resting phases of each heartbeat. Here’s what the numbers mean:
• Systolic pressure. The first (top) number in a blood pressure reading, this is the amount of pressure your heart generates when pumping blood through your arteries to the rest of your body.
• Diastolic pressure. The second (bottom) number in a blood pressure reading, this refers to the amount of pressure in your arteries when your heart is at rest between beats.
Current guidelines identify normal blood pressure as equal to or lower than 120/80 — many experts think 115/75 is even better.
Although you can get an accurate blood pressure reading at any given time, blood pressure isn’t always the same. It can vary considerably in a short amount of time — sometimes from one heartbeat to the next, depending on body position, breathing rhythm, stress level, physical condition, medications you take, what you eat and drink, and even time of day. Blood pressure is usually lowest at night and rises sharply on waking.