What is rosacea? Rosacea (ro-ZAY-she-ah) is a long-term disease that causes reddened skin and pimples, usually on the face. It can also make skin thicker and cause eye problems.

What is osteonecrosis? Your bones are made up of living cells that need a blood supply to stay healthy. In osteonecrosis, blood flow to part of a bone is reduced. This causes death of bone tissue, and the bone can eventually break down and the joint will collapse. Osteonecrosis can happen to any bone, but most often it develops in the ends of long bones, such as the: Thigh bone. Upper arm bone. Less often, the bones of the elbows, ankles, feet, wrists, and hands are affected. When the disease involves part of a bone in a joint, it can

What is alopecia areata? Alopecia areata is a disease that causes hair loss. In alopecia areata, the immune system attacks the structures in skin that form hair (hair follicles). Alopecia areata usually affects the head and face, though hair can be lost from any part of the body. Hair typically falls out in small, round patches about the size of a quarter. In some cases, hair loss is more extensive.

What is back pain? Back pain is one of the most common medical problems in the United States. It might feel like a dull, constant ache or a sudden, sharp pain. Back pain can result from: An accident. A fall. Lifting something heavy. Changes that happen in the spine as you age. A disorder or medical condition. Treatment depends on the cause and symptoms of your pain. You can do things to improve your health and lower your chance of developing chronic (long-lasting) back pain.

What is fibromyalgia? Fibromyalgia is a long-lasting or chronic disorder that causes muscle pain and fatigue (feeling tired). If you have fibromyalgia, you have pain and tenderness throughout your body. Sometimes you may have two or more chronic pain conditions at the same time, such as: Chronic fatigue syndrome. Endometriosis. Irritable bowel syndrome. Interstitial cystitis. Temporomandibular joint dysfunction (TMJ). Vulvodynia.

What is psoriatic arthritis? Psoriatic arthritis is a condition that causes swelling and pain in joints and the places where tendons and ligaments attach to bones. Most people who develop psoriatic arthritis already have psoriasis (a skin disease), but a small number have joint pain before the skin rash.