Adrenal cancer is a rare cancer that starts in the adrenal glands. You have 2 adrenal glands. One sits on top of each kidney. Learn more about symptoms, diagnosis, and treatments.

Adrenal insufficiency is a disorder that occurs when the adrenal glands don't make enough of the hormone cortisol. This hormone controls blood pressure and affects how your immune system works.

Afferent loop syndrome is a complication of certain types of stomach surgery.

African sleeping sickness (African trypanosomiasis) is a disease caused by a parasite. It is passed on by the bite of the infected tsetse fly.

Age-related hearing loss (presbycusis) is the slow loss of hearing in both ears. It’s a common problem linked to aging.

Age-related macular degeneration (AMD) is a disease that affects a person’s central vision. It's the most common cause of severe eyesight loss among people age 50 and older.

People who have AIDS are much more likely to get certain types of cancer than people without the disease.

AIDS-related lymphoma is a type of cancer called non-Hodgkin lymphoma. It grows in some people with AIDS. AIDS is a disease that weakens the immune system. AIDS raises the risk for long-term (chronic) disease, such as cancer.

Alagille syndrome is an inherited condition in which bile builds up in the liver because there are too few bile ducts to drain the bile. This results in liver damage.

Alcohol-induced liver disease is caused by heavy use of alcohol. The liver's job is to break down alcohol. If you drink more than it can process, it can become badly damaged.

Alcoholic hepatitis is liver inflammation and damage cause by drinking too much alcohol over time.

Arthritis refers to a group of disorders that involve the body’s joints and have similar symptoms, including pain, stiffness, and swelling. Learn about the different types of arthritis and their treatment.

Anaphylaxis is a potentially life-threatening allergic reaction. Common causes of anaphylaxis are allergies to penicillin, bee stings, aspirin, eggs, peanuts, and nuts. In this video, you'll find out other possible causes, what ...

Allergic rhinitis is also known as "hay fever." The symptoms can be seasonal, especially in the spring and fall, or year round. In this video, you'll learn what happens when you have allergic rhinitis and what you can do to minimize ...

Allergic rhinitis can happen on a seasonal basis or year-round. There is often a family history of allergic rhinitis, eczema, asthma, or food allergy. Read on to learn details about treating and managing this condition.

Allergies are problems of the immune system. Most allergic reactions happen when the immune system reacts to a “false alarm.” Normally, the human body defends itself against harmful things such as viruses or bacteria. But sometimes the ...

Allergies are problems of the immune system. Normally the immune system attacks harmful things such as viruses or bacteria. But sometimes it overreacts and responds to things that are normally harmless. These include dust, mold, pollen, ...

Thalassemia is an inherited blood disorder. It is passed down from one or both parents through their genes. Learn about the4 types of alpha thalassemia, symptoms, treatment options, and more.

Alpha thalassemia is an inherited blood disorder. This means it is passed down through the parent’s genes. It causes anemia in affected children. Anemia is a low red blood cell or low hemoglobin level. Hemoglobin is the part of red blood...

Alzheimer disease is a disease that affects the brain and nervous system. It is a type of dementia that happens when nerve cells in the brain die.

Amenorrhea means you haven't had your period for more than 3 cycles. It can be caused by a variety of things including overexercising, being overweight, or due to an ovulation problem.

Amenorrhea is when a girl's menstrual bleeding (period) doesn't occur.

Amniocentesis is a test that can help answer questions about your baby’s health. But not every woman needs to have this test. Watch and see how an amniocentesis is done and find out if it’s the right test for you.

Ampullary cancer, or ampullary carcinoma, is a life-threatening cancer that forms in a body part called the ampulla of Vater in the duodenum, where the pancreatic and bile ducts release their secretions into the intestines.

Amyotrophic lateral sclerosis is a fatal neurological disorder that causes progressive degeneration of nerve cells in the spinal cord and brain. It is often referred to as Lou Gehrig disease.

The anus is the last part of the digestive tract. Most anal cancers start in the cells that make the inside lining of the anus. Learn more about symptoms, diagnosis, and treatments.

An anal fissure is a small, painful tear in the lining of the anus. Anal fissures may hurt and bleed during or after a bowel movement, but about 90% heal without surgery.