Blood Pressure Basics

By definition, blood pressure is the force of blood against the walls of arteries. Blood pressure is recorded as two numbers—the systolic pressure (as the heart beats) over the diastolic pressure (as the heart relaxes between beats). The measurement is written one above or before the other, with the systolic number on top and the diastolic number on the bottom. For example, a blood pressure measurement of 120/80 mmHg (millimeters of mercury) is expressed verbally as "120 over 80." Normal blood pressure is less than 120 mmHg systolic and less than 80 mmHg diastolic.

Know the Numbers:

  • Normal: Less than 120 over 80 (120/80)
  • Prehypertension: 120-139 over 80-89
  • Stage 1 high blood pressure: 140-159 over 90-99
  • Stage 2 high blood pressure: 160 and above over 100 and above

The exact causes of high blood pressure are not known, but several factors and conditions may play a role in its development, including:

  • Smoking
  • Being overweight or obese
  • Lack of physical activity
  • Too much salt in the diet
  • Too much alcohol consumption (more than 1 to 2 drinks per day)
  • Stress
  • Older age
  • Genetics
  • Family history of high blood pressure
  • Chronic kidney disease
  • Adrenal and thyroid disorders

Primary or 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

High blood pressure often causes no symptoms. This is a scary thought. All the more reason for you to know the symptoms beforehand. You may even want to get your blood pressure measured regularly. Sometimes people with elevated blood pressure may experience headaches dizziness blurred vision nausea vomiting chest pains or shortness of breath. People often do not seek medical care until they have symptoms arising from the organ damage caused by chronic high blood pressure. The following types of organ damage are commonly seen in chronic high blood pressure:

  • Heart attack
  • Heart failure
  • Stroke or transient ischemic attack
  • Kidney failure
  • Eye damage with progressive vision loss
  • Peripheral arterial disease causing leg pain with walking