High blood pressure is a common condition in which the long-term 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 both 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. Even without symptoms, damage to blood vessels and your heart continues and can be detected. Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke.

High blood pressure generally 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.

Symptoms

Most people with high blood pressure have no signs or symptoms, even if blood pressure readings reach dangerously high levels.

A few people with high blood pressure may have headaches, shortness of breath or nosebleeds, but these signs and symptoms aren't specific and usually don't occur until high blood pressure has reached a severe or life-threatening stage.

When to see a doctor

You'll likely have your blood pressure taken as part of a routine doctor's appointment.

Ask your doctor for a blood pressure reading at least every two years starting at age 18. If you're age 40 or older, or you're 18 to 39 with a high risk of high blood pressure, ask your doctor for a blood pressure reading every year.

Blood pressure generally should be checked in both arms to determine if there's a difference. It's important to use an appropriate-sized arm cuff.

Your doctor will likely recommend more frequent readings if you've already been diagnosed with high blood pressure or have other risk factors for cardiovascular disease. Children age 3 and older will usually have blood pressure measured as a part of their yearly checkups.

If you don't regularly see your doctor, you may be able to get a free blood pressure screening at a health resource fair or other locations in your community. You can also find machines in some stores that will measure your blood pressure for free.

Public blood pressure machines, such as those found in pharmacies, may provide helpful information about your blood pressure, but they may have some limitations. The accuracy of these machines depends on several factors, such as a correct cuff size and proper use of the machines. Ask your doctor for advice on using public blood pressure machines.

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 primary (essential) 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:

• Obstructive sleep apnea
• Kidney problems
• Adrenal gland tumors
• Thyroid problems
• Certain defects you're born with (congenital) in blood vessels
• 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