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.



Acne affects the skin’s oil glands. The small holes in your skin (pores) connect to oil glands under the skin. These glands make an oily substance called sebum.

Alopecia Areata

Alopecia areata attacks your hair follicles (the part of your skin that makes hair). In most cases, hair falls out in small, round patches.

Ankylosing Spondylitis

Ankylosing spondylitis is arthritis that affects the spine. It often involves redness, heat, swelling, and pain in the spine or in the joint where the bottom of the spine joins the pelvic bone.


"Arthritis" means joint inflammation. Although joint inflammation is a symptom or sign rather than a specific diagnosis, the term arthritis is often used to refer to any disorder that affects 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

Atopic dermatitis is a skin disease that causes the skin to become very itchy. Scratching leads to redness, swelling, cracking, “weeping” clear fluid, crusting, and scaling.

Autoimmune Diseases

Autoimmune diseases happen when your immune cells attack your body by mistake. These diseases can affect almost any part of the body.

Autoinflammatory Diseases

Autoinflammatory diseases cause your immune cells to attack your body by mistake. Autoinflammatory diseases cause your immune cells to attack your body by mistake. This can cause fever, rash, joint swelling, and more.


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 a sudden, sharp pain that makes it hard to move.

Behçet’s Disease

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


Bursitis is a common condition that causes swelling and pain around muscles and bones.


Cicatricial Alopecia

Cicatricial alopecia is a group of conditions that destroy hair follicles. Hair follicles are the part of the skin where the hair grows.



Eczema is a general term for several types of inflammation of the skin. Atopic dermatitis is the most common form of eczema.

Epidermolysis Bullosa

Epidermolysis bullosa is a group of diseases that cause painful blisters to form on the skin. These blisters can cause serious problems if they become infected.



Fibromyalgia is a long-lasting or chronic disorder that causes muscle pain and fatigue (feeling tired).

Fibrous Dysplasia

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


Giant Cell Arteritis

Giant cell arteritis causes the arteries of the scalp and neck to become red, hot, swollen, or painful. The arteries most affected are those in the temples on either side of the head.


Gout 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.


Heritable Disorders of Connective Tissue

The more than 200 heritable disorders of connective are related to problems in genes that are 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.



Ichthyosis is a disorder that causes dry, thickened skin that may look like fish scales.


Joint Replacement Surgery

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

Juvenile Arthritis

Juvenile arthritis is the term used to describe arthritis in children. Arthritis is caused by inflammation of the joints.


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.


Lichen Sclerosus

Lichen sclerosus usually affects the skin of the genital and anal areas. The disease can also appear on the upper body, breasts, and upper arms.


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.


Marfan Syndrome

Marfan syndrome is a disorder that affects connective tissue. Connective tissue supports many parts of your body.



Osteoarthritis damages the slippery tissue that covers the ends of bones in a joint. This allows bones to rub together. The rubbing causes pain, swelling, and loss of motion of the joint.

Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a disease that affects your bones. OI is also called brittle bone disease because it causes bones to be weak and break easily.


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


In osteopetrosis, bones are too thick but easily broken. This happens when new bone grows faster than old bone is removed.


Osteoporosis is a disease in which your bones become weak and are more likely to break.


Pachyonychia Congenita

Pachyonychia congenita is a very rare disorder. It causes thick nails and painful calluses on the bottoms of the feet. In some cases, blisters also form on the palms of the hands.

Paget’s Disease of Bone

Paget’s disease 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 is a disease where the body’s immune system attacks healthy cells in the top layer of skin (epidermis). It causes blisters on the skin and in the mouth, nose, throat, eyes, and genitals.

Polymyalgia Rheumatica

Polymyalgia rheumatica causes muscle pain and stiffness in the neck, shoulder, and hip.


Psoriasis is a skin disease that causes red, scaly skin that may feel painful, swollen, or hot.

Psoriatic Arthritis

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


Raynaud’s Phenomenon

Raynaud’s phenomenon is a disease that affects your blood vessels. During "attacks," your body does not send enough blood to the hands and feet for a period of time.

Reactive Arthritis

Reactive arthritis is pain or swelling in a joint that is caused by an infection in your body. You may also have red, swollen eyes and a swollen urinary tract.

Rheumatoid Arthritis

Rheumatoid arthritis is a disease that affects your joints. It causes pain, swelling, and stiffness.


Rosacea (ro-ZAY-she-ah) is a long-term disease that causes reddened skin and pimples, usually on the face.



Scleroderma is the name for a group of diseases that cause patches of tight, hard skin. Some forms of scleroderma can also damage your blood vessels and internal organs.

Scoliosis in Children and Adolescents

Scoliosis is a disorder in which there is a sideways curve of the spine. Curves are often S-shaped 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.

Sjögren’s Syndrome

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

Spinal Stenosis

Spinal stenosis is 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 two or more bones at a joint). A strain is an injury to a muscle or tendon (fibrous cords of tissue that connect muscle to bone).

Systemic Lupus Erythematosus (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.



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



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