High blood pressure makes your heart work harder than normal. Both the heart and arteries are then more prone to injury. High blood pressure increases the risk of heart attacks, strokes, kidney failure, eye damage, congestive heart failure and fatty buildups in arteries called atherosclerotic plaques. If you have high blood pressure, are obese, smoke, or have high blood cholesterol levels or diabetes, your risk of heart attack or stroke goes up several times.

If high blood pressure isn't treated, your heart may have to work harder and harder to pump enough blood and oxygen to your body's organs and tissues. A heart forced to work harder for a long time tends to enlarge and weaken. A slightly enlarged heart may work well, but one that's enlarged a lot has a hard time doing its job.

High blood pressure also hurts arteries and arterioles, the very small arteries that connect larger arteries to the tiny capillaries. They eventually become scarred, hardened and less elastic. This may happen as you get older, but high blood pressure speeds up the process, probably because it damages the artery wall and speeds atherosclerosis.

Arterial damage is bad because hardened or narrowed arteries may not be able to supply enough blood to your body's organs. And if your organs don't get enough oxygen and nutrients, they can't work properly. Another risk is that atherosclerotic plaques may rupture. Then a blood clot forms, shutting off normal blood supply to part of your body.

Related AHA publications:

• Heart and Stroke Facts
• Understanding and Controlling Your High Blood Pressure brochure (also in Spanish) 
• Shaking Your Salt Habit brochure
• High Blood Pressure in African Americans brochure
• High Blood Pressure and Stroke brochure
• "What Is High Blood Pressure?" and "How Can I Reduce High Blood Pressure?" printable sheets in Answers By Heart kit (also in Spanish kit)
• "What Is High Blood Pressure Medicine?", "Why Should I Limit Sodium?" and "How Can I Monitor My Weight and Blood Pressure?" in Answers By Heart kit

Related AHA Scientific Statements
Blood Pressure
Hypertension