Scorpions are a type of eight-legged animal called an arachnid. They live in warm, dry climates all over the world. In the United States, they live mostly in the South and Southwest. Scorpions have a front pair of claws and a flexible tail. The tip of the tail holds the scorpion’s stinger and two glands that contain a poisonous substance …

Sclerosing mesenteritis is a rare disease that affects your mesentery, the tissue that attaches parts of your intestines to the back wall of your abdomen. “Mesenteritis” means inflammation of the mesentery, and “sclerosing” means scarring. Sclerosing mesenteritis causes chronic inflammation of the mesentery. Over time, chronic inflammation causes scarring or “fibrosis” of the tissues, making them harden. Your mesentery is part of …

Scleroderma is a rare condition that makes your body produce tissue that’s thicker than it should be. Scleroderma usually affects your skin, but can cause symptoms in any tissue throughout your body. Scleroderma is an autoimmune disorder. Autoimmune disorders happen when your immune system accidentally attacks your body instead of protecting it. Experts don’t know why your immune system turns on you. It’s …

Sciatica is nerve pain from an injury or irritation to your sciatic nerve. In addition to pain, it can involve tingling or numbness in your back or butt that may also radiate down your leg. More severe symptoms are also possible. Your sciatic nerve is the longest and thickest nerve in your body. It’s up to 2 centimeters wide (a U.S. …

A spinal cord injury (SCI) happens when there’s damage to your spinal cord, a thick bundle of nerve fibers that allows your brain to communicate with other nerves almost everywhere else in your body. These injuries can range from minor and manageable to severe and permanent. The spinal cord is one of the two components of your central nervous system (CNS). Your nervous system is like …

Schizophrenia is a psychiatric condition that has severe effects on your physical and mental well-being. It disrupts how your brain works, interfering with things like your thoughts, memory, senses and behaviors. As a result, you may struggle in many parts of your day-to-day life. Untreated schizophrenia often disrupts your relationships (professional, social, romantic and otherwise). It can also cause you to have …

Schizoaffective disorder is a mental health condition that includes symptoms of both schizophrenia and mood disorders. Schizophrenia affects the way you think, act, perceive reality and express emotions. Mood disorders change your feelings, energy levels and behaviors. There’s no cure for schizoaffective disorder, but treatment can help manage your symptoms and improve your quality of life. What are the types of schizoaffective disorder? There are …

Scarlet fever (scarlatina) is an infection caused by group A Streptococcus bacteria. It’s the same bacteria that causes strep throat. The bacteria create a toxin (poison) that causes a bright red rash that spreads all over your body. That’s why it’s called scarlet fever. The rash is also bumpy, so it’s sometimes called a sandpaper rash. What is scarlet fever tongue? One of …

Spontaneous coronary artery dissection (SCAD) occurs when there’s a separation or tear in the wall of a coronary artery. The tear can occur in any one of the three layers of the coronary artery wall. Blood seeps between the layers. This trapped blood causes the artery to bulge inward. The bulge blocks or slows blood flow to your heart. SCAD …

The Sarcoptes scabiei mite causes scabies. These little bugs make tunnels (burrow) under your skin to live, feed and lay eggs. Your skin reacts to the mite by developing an itchy rash. Scabies spreads easily from person to person, especially among people who live close together. If one family member has scabies, a healthcare provider should check and treat other family members and …