We are pleased to bring you our refreshed mobile-friendly health information. For each health topic, you’ll find a “Basics” version, which provides essential facts, and an “In-Depth” version, which provides more details. To access NIAMS publications, check out the “View/Download/Order Publications” box at the bottom of every health topic page, or visit the NIAMS Publications Catalog.

A

Acne

What is acne? It is caused when blocked skin follicles from a plug caused by oil from glands, bacteria, and dead cells clump together and swell.

Alopecia Areata

What is alopecia areata? It is a condition that attacks your hair follicles (they make hair). In most cases, hair falls out in small, round patches.

Ankylosing Spondylitis

What is ankylosing spondylitis? It is arthritis that affects the spine, usually producing redness, heat, swelling, and pain in the spine where it joins the pelvis.

Arthritis

What is arthritis? It is joint inflammation and though it is a symptom rather than a diagnosis, the term is often used to refer to any disorder affecting the joints.

Arthritis and Rheumatic Diseases

Arthritis is often used to refer to any disorder that affects the joints. Rheumatic diseases usually affect joints, tendons, ligaments, bones, and muscles.

Atopic Dermatitis

What is atopic dermatitis? It is a skin disease causing much itchiness. Scratching leads to redness, swelling, cracking, weeping clear fluid, crusting, and scaling.

Autoimmune Diseases

What are autoimmune diseases? These diseases occur when your immune cells attack your body by mistake. These diseases can affect almost any part of the body.

Autoinflammatory Diseases

What are autoinflammatory diseases? They cause your immune cells to attack your body by mistake, and can cause fever, rash, joint swelling, and more.

B

Back Pain

Back pain is one of the most common medical problems in the United States. It can range from a dull, constant ache to sudden, sharp pain that makes it hard to move.

Behçet’s Disease

What is Behçet’s disease? It is a chronic condition that causes mouth or genital sores, and inflammation in parts of the eye.

Bursitis

What is bursitis? It is a common condition that causes swelling and pain around muscles and bones.

C

Cicatricial Alopecia

What is cicatricial alopecia? It is a group of conditions that destroy hair follicles. Hair follicles are the part of the skin where the hair grows.

E

Epidermolysis Bullosa

What is epidermolysis bullosa? It is a group of diseases causing painful blisters to form on the skin. These blisters can cause problems if they become infected.

F

Fibromyalgia

What is fibromyalgia? It is a long-lasting or chronic disorder that causes muscle pain and fatigue (feeling tired).

Fibrous Dysplasia

What is fibrous dysplasia? It happens when healthy bone is replaced with other types of tissue. Bones may become weak or oddly shaped, or they may even break.

G

Giant Cell Arteritis

What is giant cell arteritis? It causes arteries in the scalp and neck to become red, hot, swollen, or painful. Arteries most affected are those in the temples.

Gout

What is gout? It is a kind of arthritis that causes painful and stiff joints. Gout is caused by the build-up of crystals of uric acid in your joints.

Growth Plate Injuries

Injuries to the growth plate happen when a break or fracture develops near or at the end of a long bone.

H

Heritable Disorders of Connective Tissue

There are more than 200 heritable disorders of connective tissue, and they are related to problems in genes responsible for building connective tissues.

Hip Replacement Surgery

Hip replacement surgery removes damaged or diseased parts of a hip joint and replaces them with new, man-made parts.

I

Ichthyosis

What is ichthyosis? It is a disorder that causes dry, thickened skin that may look similar to fish scales.

J

Joint Replacement Surgery

Joint replacement surgery removes damaged or diseased parts of a joint and replaces them with new, man-made parts. 

Juvenile Arthritis

What is juvenile arthritis? It is the term used to describe arthritis in children. Arthritis is caused by inflammation of the joints.

K

Kids Pages

Your childhood and teen years are a prime time to learn habits that will help you keep your bones, joints, muscles, and skin healthy for years to come. Have fun exploring these pages, and come back often for updates and new features.

Knee Problems

Knee problems happen when you injure or develop disease in your knee and it can’t do its job.

L

Lichen Sclerosus

What is lichen sclerosus? It causes white spots or patches on skin of the genital and anal areas, but can appear elsewhere. Itchiness, pain, and bleeding are common.

Lupus

Lupus happens when the body’s defense system attacks healthy cells and tissues, instead of viruses and bacteria. This can damage many parts of the body.

M

Marfan Syndrome

What is Marfan syndrome? It is a disorder that affects connective tissue, which supports many parts of your body. Marfan is often a genetic disease.

O

Osteoarthritis

What is osteoarthritis? It damages the slippery tissue that covers the ends of bones, causing bones to rub together, producing pain, swelling, and loss of motion.

Osteogenesis Imperfecta

What is osteogenesis imperfecta? It is a genetic disease, also called brittle bone disease, that causes bones to be weak and break easily.

Osteonecrosis

What is osteonecrosis? It is a bone disease that results from the loss of blood supply. Without blood, the bone tissue dies, causing the bone to collapse.

Osteopetrosis

What is osteopetrosis? It is a disease when bones become too thick but are easily broken. It happens when new bone grows faster than old bone is removed.

Osteoporosis

What is osteoporosis? It is a disease in which your bones become weak and are more likely to break. There are no symptoms until a bone breaks.

P

Pachyonychia Congenita

What is pachyonychia congenita? It is a rare disorder causing thick nails and painful calluses on the bottoms of the feet and other symptoms.

Paget’s Disease of Bone

What is Paget’s disease? It is a disorder that causes bones to grow too large and weaken. You can have Paget’s disease in any bones in your body.

Pemphigus

What is pemphigus? It is a disease where the immune system attacks healthy cells in the top layer of skin, resulting in blisters.

Polymyalgia Rheumatica

What is polymyalgia rheumatica? It causes muscle pain and stiffness in the neck, shoulder, and hip, and can be accompanied by fever, weakness, and weight loss.

Psoriasis

What is psoriasis? It is a skin disease that causes red, scaly skin that may feel painful, swollen, or hot. Individuals may be susceptible to other conditions.

Psoriatic Arthritis

What is psoriatic arthritis? It can occur in people who have psoriasis (scaly red and white patches). It affects the joints and areas where tissues attach to bone.

R

Raynaud’s Phenomenon

What is Raynaud’s phenomenon? It is a disease that affects blood vessels. It causes your body to not send enough blood to the hands and feet for a period of time.

Reactive Arthritis

What is reactive arthritis? It is caused by an infection and results in joint pain and swelling. You may also have red, swollen eyes and a swollen urinary tract.

Rheumatoid Arthritis

What is rheumatoid arthritis? It is a disease that affects multiple joints, resulting in pain, swelling, and stiffness. Tiredness and fever may also be present.

Rosacea

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

S

Scleroderma

What is scleroderma? It is a group of diseases causing patches of tight, hard skin. Some forms of scleroderma also damage your blood vessels and internal organs.

Scoliosis in Children and Adolescents

What is scoliosis? It is a disorder causing a sideways curve of the spine. Curves are often S- or C-shaped. In most people, there is no known cause for this curve.

Shoulder Problems

Most shoulder problems happen when soft tissues in the shoulder region break down. The various causes and symptoms depend on the type of shoulder problem.

Sjögren’s Syndrome

What is Sjögren’s syndrome? It is a disease that affects the glands that make moisture. It most often causes dryness in the mouth and eyes.

Spinal Stenosis

What is spinal stenosis? It is the narrowing of the spine. This narrowing puts pressure on the spinal cord and nerves and can cause pain.

Sports Injuries

Sports injuries are injuries that happen when playing sports or exercising. There are two kinds of sports injuries: acute and chronic.

Sports Injuries in Youth: A Guide for Parents

Parents learn about common sports injuries among youth and the ways to prevent such injuries from happening.

Sprains and Strains

A sprain is an injury to a ligament (tissue that connects bones). A strain is an injury to a muscle or tendon (cords of tissue connecting muscle to bone).

Systemic Lupus Erythematosus (Lupus)

What is lupus? It is a disease where the body’s defense system attacks healthy cells and tissues, causing damage to many parts of the body.

T

Tendinitis

What is tendinitis? It is swelling and pain in a joint usually caused by repeated injuries to a tendon, the part of the joint that connects muscles to bones.

V

Vitiligo

Vitiligo is a disorder that causes patches of skin to become white. It happens because cells that make color in your skin are destroyed.
Last Reviewed: 04/20/2017