High blood pressure (hypertension) can quietly damage the body for years before symptoms develop. Uncontrolled high blood pressure can lead to disability, a poor quality of life, or even a deadly heart attack or stroke. Treatment and lifestyle changes can help control high blood pressure to reduce the risk of life-threatening complications.

Damage to the arteries

Healthy arteries are flexible, strong and elastic. Their inner lining is smooth so that blood flows freely, supplying vital organs and tissues with nutrients and oxygen. High blood pressure (hypertension) gradually increases the pressure of blood flowing through the arteries. Hypertension may cause:

• Damaged and narrowed arteries. High blood pressure can damage the cells of the arteries' inner lining. When fats from the diet enter the bloodstream, they can collect in the damaged arteries. Eventually, the artery walls become less elastic, limiting blood flow throughout the body.
• Aneurysm. Over time, the constant pressure of blood moving through a weakened artery can cause a section of its wall to enlarge and form a bulge (aneurysm). An aneurysm can potentially rupture and cause life-threatening internal bleeding. Aneurysms can form in any artery, but they're most common in the body's largest artery (aorta).

Damage to the heart

High blood pressure can cause many heart problems, including:

• Coronary artery disease. Arteries narrowed and damaged by high blood pressure have trouble supplying blood to the heart. Too little blood flow to the heart can lead to chest pain (angina), irregular heart rhythms (arrhythmias) or a heart attack.
• Enlarged left heart. High blood pressure forces the heart to work harder to pump blood to the rest of the body. This causes the lower left heart chamber (left ventricle) to thicken. A thickened left ventricle increases the risk of heart attack, heart failure and sudden cardiac death.
• Heart failure. Over time, the strain on the heart caused by high blood pressure can cause the heart muscle to weaken and work less efficiently. Eventually, the overwhelmed heart begins to fail.

Damage to the brain

The brain depends on a nourishing blood supply to work properly. High blood pressure may affect the brain in the following ways:

• Transient ischemic attack (TIA). Sometimes called a ministroke, a TIA is a brief, temporary disruption of blood supply to the brain. Hardened arteries or blood clots caused by high blood pressure can cause TIA. TIA is often a warning sign of a full-blown stroke.
• Stroke. A stroke occurs when part of the brain doesn't get enough oxygen and nutrients, causing brain cells to die. Blood vessels damaged by high blood pressure can narrow, rupture or leak. High blood pressure can also cause blood clots to form in the arteries leading to the brain, blocking blood flow and potentially causing a stroke.
• Dementia. Narrowed or blocked arteries can limit blood flow to the brain, leading to a certain type of dementia (vascular dementia). A stroke that interrupts blood flow to the brain can also cause vascular dementia.
• Mild cognitive impairment. This condition is a transition stage between the changes in understanding and memory that generally come with aging and the more-serious problems caused by dementia. Studies suggest that high blood pressure can lead to mild cognitive impairment.

Damage to the kidneys

Kidneys filter excess fluid and waste from the blood — a process that requires healthy blood vessels. High blood pressure can damage the blood vessels in and leading to the kidneys. Having diabetes in addition to high blood pressure can worsen the damage. Kidney problems caused by high blood pressure include:

• Kidney scarring (glomerulosclerosis). This type of kidney damage occurs when tiny blood vessels within the kidney become scarred and unable to effectively filter fluid and waste from the blood. Glomerulosclerosis can lead to kidney failure.
• Kidney failure. High blood pressure is one of the most common causes of kidney failure. Damaged blood vessels prevent kidneys from effectively filtering waste from the blood, allowing dangerous levels of fluid and waste to collect. Treatment may include dialysis or kidney transplantation.

Damage to the eyes

High blood pressure can damage the tiny, delicate blood vessels that supply blood to the eyes, causing:

• Damage to the blood vessels in the retina (retinopathy). Damage to the blood vessels in the light-sensitive tissue at the back of the eye (retina) can lead to bleeding in the eye, blurred vision and complete loss of vision. Having diabetes in addition to high blood pressure increase the risk of retinopathy.
• Fluid buildup under the retina (choroidopathy). Choroidopathy can result in distorted vision or sometimes scarring that impairs vision.
• Nerve damage (optic neuropathy). Blocked blood flow can damage the optic nerve, leading to bleeding within the eye or vision loss.

Sexual dysfunction

The inability to have and maintain an erection (erectile dysfunction) becomes increasingly common in men as they reach age 50. But men with high blood pressure are even more likely to experience erectile dysfunction. That's because limited blood flow caused by high blood pressure can block blood from flowing to the penis. Women may also experience sexual dysfunction as a result of high blood pressure. Reduced blood flow to the vagina can lead to a decrease in sexual desire or arousal, vaginal dryness, or difficulty achieving orgasm.

High blood pressure emergencies

High blood pressure is usually a chronic condition that gradually causes damage over years. But sometimes blood pressure rises so quickly and severely that it becomes a medical emergency requiring immediate treatment, often with hospitalization. In these situations, high blood pressure can cause:

• Blindness
• Chest pain
• Complications in pregnancy (preeclampsia or eclampsia)
• Heart attack
• Memory loss, personality changes, trouble concentrating, irritability or progressive loss of consciousness
• Severe damage to the body's main artery (aortic dissection)
• Stroke
• Sudden impaired pumping of the heart, leading to fluid backup in the lungs resulting in shortness of breath (pulmonary edema)
• Sudden loss of kidney function