Adenoviruses are a group of viruses that cause a variety of infections. These include the common cold, conjunctivitis, and croup.

An adjustment disorder is an unhealthy emotional or behavioral reaction to a stressful event or change in a person's life. The response happens within 3 months of the stressful event.

Scoliosis is a side-to-side curve in the back. Adolescent idiopathic scoliosis (AIS) occurs at age 10 or later. It may start at puberty or during a growth spurt in the teens.

Adrenal tumors occur when cells in the adrenal gland cause an oversupply of certain powerful hormones. This can cause a variety of conditions, from high blood pressure to panic attacks. Only about five percent of tumors that grow inside ...

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.

Even after we stop growing, adults still need growth hormone. Growth hormone is a protein made by the pituitary gland and released into the blood. Growth hormone plays a role in healthy muscle, how our bodies collect fat (especially ...

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.

The spine is made up of bones and discs. The discs are like gelatin. As we get older, the discs start to dry out and no longer cushion the bones. Without the cushioning of the discs, the nerve roots or spinal cord (or both) start to get ...

A person who has been infected by the human immunodeficiency virus (HIV) is diagnosed as having AIDS after developing one of the illnesses that the Centers for Disease Control has identified as an indicator of AIDS. An HIV-positive ...

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.

AL Amyloidosis is caused by the accumulation of an immunoglobulin light chain protein. Typically, the protein is caused by a malignant or pre-malignant growth of identical, (clonal) lymphocytes or plasma cells that continue to produce ...

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.

Allergic fungal sinusitis (AFS) is a common type of fungal infection in the sinuses. The infecting fungi are found in the environment and cause an allergic reaction which results in thick fungal debris, sticky mucus and blockage of the ...

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.

Allergic sinusitis, common in early childhood, is a reaction to exposure to inhalants such as dust, pollen, smoke and animal dander. A family history or allergic sinusitis may predispose certain individuals to be sensitive to certain ...

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...

Alpha-1 antitrypsin deficiency (A1AD) is a disease passed down from your parents. It can cause lung and liver disease. Alpha-1 antitrypsin is a protein the liver makes to protect the lungs and other organs from harmful effects that may ...

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.