All Diseases

Sheehan's syndrome is a condition that affects women who lose a life-threatening amount of blood or who have severe low blood pressure during or after childbirth. These factors can deprive your body of oxygen and can seriously damage vital tissues and organs. In the case of Sheehan's syndrome, the damage occurs to the pituitary gland — a small gland at the base of your brain.

Sheehan's syndrome causes the permanent underproduction of essential pituitary hormones (hypopituitarism). Also called postpartum hypopituitarism, Sheehan's syndrome is rare in industrialized nations. But it's still a major threat to women in developing countries.

Treatment of Sheehan's syndrome involves hormone replacement therapy.

Shellfish allergy is an abnormal response by the body's immune system to proteins in certain marine animals. Shellfish include marine animals with shells, such as shrimp, crab, oysters and lobster, as well as octopus, squid and scallops.

Some people with shellfish allergy react to all shellfish; others react to only certain kinds. Reactions range from mild symptoms — such as hives or a stuffy nose — to severe and even life-threatening.

If you think you have a shellfish allergy, talk to your doctor. Tests can help confirm a shellfish allergy, so you can take steps to avoid future reactions.

Shigella infection (shigellosis) is an intestinal disease caused by a family of bacteria known as shigella. The main sign of shigella infection is diarrhea, which often is bloody.

Shigella can be passed through direct contact with the bacteria in the stool. For example, this can happen in a child care setting when staff members don't wash their hands well enough after changing diapers or helping toddlers with toilet training. Shigella bacteria also can be passed in contaminated food or by drinking or swimming in contaminated water.

Children between the ages of 2 and 4 are most likely to get shigella infection. A mild case usually clears up on its own within a week. When treatment is needed, doctors generally prescribe antibiotics.

The term "shin splints" refers to pain along the shinbone (tibia) — the large bone in the front of your lower leg. Shin splints are common in runners, dancers and military recruits.

Medically known as medial tibial stress syndrome, shin splints often occur in athletes who have recently intensified or changed their training routines. The muscles, tendons and bone tissue become overworked by the increased activity.

Most cases of shin splints can be treated with rest, ice and other self-care measures. Wearing proper footwear and modifying your exercise routine can help prevent shin splints from recurring.

Shingles is a viral infection that causes a painful rash. Although shingles can occur anywhere on your body, it most often appears as a single stripe of blisters that wraps around either the left or the right side of your torso.

Shingles is caused by the varicella-zoster virus — the same virus that causes chickenpox. After you've had chickenpox, the virus lies inactive in nerve tissue near your spinal cord and brain. Years later, the virus may reactivate as shingles.

While it isn't a life-threatening condition, shingles can be very painful. Vaccines can help reduce the risk of shingles, while early treatment can help shorten a shingles infection and lessen the chance of complications.

Sick sinus syndrome — also known as sinus node disease or sinus node dysfunction — is the name for a group of heart rhythm problems (arrhythmias) in which the sinus node — the heart's natural pacemaker — doesn't work properly.

The sinus node is an area of specialized cells in the upper right chamber of the heart that controls the rhythm of your heart. Normally, the sinus node produces a steady pace of regular electrical impulses. In sick sinus syndrome, these signals are abnormally paced.

A person with sick sinus syndrome may have heart rhythms that are too fast, too slow, punctuated by long pauses — or an alternating combination of all of these rhythm problems. Sick sinus syndrome is relatively uncommon, but the risk of developing sick sinus syndrome increases with age.

Many people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm.

Sickle cell anemia is an inherited form of anemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen throughout your body.

Normally, your red blood cells are flexible and round, moving easily through your blood vessels. In sickle cell anemia, the red blood cells become rigid and sticky and are shaped like sickles or crescent moons. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body.

There's no cure for most people with sickle cell anemia. However, treatments can relieve pain and help prevent further problems associated with sickle cell anemia.

Sinus headaches are headaches that may accompany sinusitis, a condition in which the membranes lining your sinuses become swollen and inflamed. You may feel pressure around your eyes, cheeks and forehead. Perhaps your head throbs.

Many people who assume they have sinus headaches, including many who have received a diagnosis of sinus headaches, actually have migraines or tension headaches.

When sinus headaches caused by sinusitis do occur, proper diagnosis and treatment are the keys to relief.

Sjogren's (SHOW-grins) syndrome is a disorder of your immune system identified by its two most common symptoms — dry eyes and a dry mouth.

Sjogren's syndrome often accompanies other immune system disorders, such as rheumatoid arthritis and lupus. In Sjogren's syndrome, the mucous membranes and moisture-secreting glands of your eyes and mouth are usually affected first — resulting in decreased production of tears and saliva.

Although you can develop Sjogren's syndrome at any age, most people are older than 40 at the time of diagnosis. The condition is much more common in women. Treatment focuses on relieving symptoms.

Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the sun. But this common form of cancer can also occur on areas of your skin not ordinarily exposed to sunlight.

There are three major types of skin cancer — basal cell carcinoma, squamous cell carcinoma and melanoma.

You can reduce your risk of skin cancer by limiting or avoiding exposure to ultraviolet (UV) radiation. Checking your skin for suspicious changes can help detect skin cancer at its earliest stages. Early detection of skin cancer gives you the greatest chance for successful skin cancer treatment.