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Chances are you or someone you know has arthritis. It's the No. 1 cause of disability. Arthritis affects nearly 60 million American adults and 300,000 children, according to the Arthritis Foundation.

Learn about the more common types of arthritis, the symptoms and how to treat and live with arthritis.

What is arthritis?

Arthritis is the swelling of one or more joints. Arthritis includes more than 100 conditions that affect the joints, tissues around the joint, and other connective tissues.

Learn more about arthritis and rheumatology at UC Davis Health

Below are the most common types of arthritis and related conditions.

1. Osteoarthritis

Osteoarthritis is the most common form of arthritis. More than 32.5 million Americans have osteoarthritis.

Symptoms of osteoarthritis

When the cartilage in a joint breaks down, the bone underneath begins to change. These changes can get worse over time, causing pain, stiffness and swelling. Some people may also notice decreased range of motion or flexibility.

Osteoarthritis causes and risk factors

Osteoarthritis is caused by wear and tear or damage of joint cartilage between bones. It most often shows up in the hands, hips and knees.

Some risk factors of osteoarthritis, according to the Centers for Disease Control and Prevention (CDC), include:

  • Overuse joint injuries, including knee bending and repeated stress on a joint
  • Older age
  • Being a woman especially over age 50
  • Being overweight, which puts extra stress on joints (especially the hips and knees)
  • Genetics
  • Race

Learn more about osteoarthritis and how you can manage or improve your quality of life

2. Rheumatoid arthritis (also called RA)

Rheumatoid arthritis can be one of the most disabling forms of arthritis. It's the most common form of autoimmune arthritis, affecting more than 1.3 million Americans. About 75% of those are women, according to the American College of Rheumatology. RA typically begins between ages 30 and 50 but can show up at any age.

Symptoms of rheumatoid arthritis

Rheumatoid arthritis causes joint pain, stiffness, swelling and decreased movement of the joints. RA often affects small joints in the hands and feet but can affect other organs like eyes and skin. It typically causes the most stiffness in the morning, which can be a sign of rheumatoid arthritis as opposed to other conditions.

Other signs of RA can include loss of energy, low-grade fever, loss of appetite, and firm lumps below the skin in areas like the elbows and hands.

Causes and risk factors of rheumatoid arthritis

Rheumatoid arthritis is an autoimmune disease. Normally, your immune system attacks bacteria and viruses by creating inflammation. With an autoimmune disease, your immune system mistakenly sends inflammation to healthy tissue.

Learn more about what happens in rheumatoid arthritis and other symptoms

3. Fibromyalgia

Fibromyalgia is a long-lasting disorder that causes widespread pain and tenderness. It's most common in women but men can get it too. Fibromyalgia doesn't damage the joints or muscles. It can be difficult to diagnose fibromyalgia. Talk to your health care provider to learn about getting a diagnosis.

Symptoms of fibromyalgia

The main symptoms of fibromyalgia include:

  • Chronic pain throughout the whole body or in multiple places. People often describe it as aching, burning or throbbing.
  • Fatigue
  • Trouble sleeping
  • Muscle and joint stiffness
  • Tenderness to touch
  • Problems concentrating or thinking clearly
  • Sensitivity to light, noise, smells, and temperature
  • Numbness or tingling in arms and legs

Causes and risk factors of fibromyalgia

The cause of fibromyalgia is unknown. However, it may be linked to genetics and family history, but not much is known about the specific genes involved. Researchers do know that fibromyalgia is not from an autoimmune, joint inflammation or muscle disorder.

Fibromyalgia may be triggered by certain factors, such as spine problems, arthritis injury, or other types of physical stress. Emotional stress may also trigger fibromyalgia, according to the American College of Rheumatology.

Women are twice as likely to have fibromyalgia than men. Middle-aged people and people with certain diseases, such as lupus and rheumatoid arthritis, are more likely to be diagnosed with fibromyalgia. People with a family member who has the disease are at increased risk for the disease.

Learn more about fibromyalgia and ways you can go on living your life

4. Gout

Gout is a common type of inflammatory arthritis that causes swelling and pain in the joints. It can flare up for a week or two and then go away. The flare-ups often happen in one of the big toes or lower limbs.

Some people with gout may be likely to develop other conditions, such as those related to the heart or kidneys. They can include high blood pressure, chronic kidney disease, and diabetes.

Gout is one of the most controllable forms of arthritis. Early diagnosis, treatment and lifestyle changes are important factors to decreasing symptoms and even getting rid of gout.

Symptoms of gout

Pain in the joint is the most common symptom of gout. It usually starts in a big toe but can show up in other joints throughout the body. Gout flares usually start at night and can cause so much pain that the person wakes up. Other symptoms can include swelling, redness, and feeling hot.

Causes and risk factors of gout

Gout is caused by a condition called hyperuricemia. This is where there's too much uric acid in the body. When there's too much uric acid, crystals can build up in joints, fluids and tissues. This causes inflammation of the joints.

Gout flares are often trigged by certain foods or medications, alcohol, physical trauma or specific illnesses. Men are more likely to have gout, but women can get gout typically after menopause. Being obese can also increase your risk of gout.

Learn more about gout and the things that can increase your risk

5. Lupus

Lupus is a long-lasting autoimmune disease that can cause pain to any part of the body. It most commonly affects skin, joints, and internal organs like kidneys and heart. About 1.5 million Americans have lupus, according to the Lupus Foundation of America. Ninety percent of those are women, who typically develop lupus between the ages of 15-44.

Symptoms of lupus

Symptoms can vary from person to person, and they may come and go over time. They can include:

  • Muscle and joint pain
  • Fever
  • Rashes
  • Chest pain
  • Hair loss
  • Sun or light sensitivity
  • Kidney problems, such as high blood pressure, decreased kidney function, etc.
  • Mouth sores
  • Fatigue or extreme tiredness
  • Memory problems

Causes and risk factors of lupus

Researchers are not exactly sure what causes lupus, but they do know that you can't get it from someone else. Genetic factors play a role in getting lupus. Other possible factors include the environment, hormones such as estrogen, and problems with the immune system, according to the CDC.

Learn more about lupus and the early symptoms you should watch for

6. Psoriatic Arthritis

Psoriatic arthritis is an inflammatory autoimmune condition that causes inflamed joints. It often, but not always, shows up in people who have psoriasis, an autoimmune skin condition. Psoriatic arthritis affects large joints like knees and shoulders, as well as fingers, toes, the back or the pelvis.

Symptoms of psoriatic arthritis

Symptoms of psoriatic arthritis typically show up between ages 30 and 50. Symptoms can include mild or more chronic inflammation that can cause joint damage if it's not treated correctly. Psoriatic arthritis symptoms can include:

  • Scaly, inflamed patches of skin often on the scalp, elbows or knees
  • Joint stiffness and swelling (often worse in the morning or after resting)
  • Pitting or tiny dents on your nails, or nails separating from the nail bed
  • Tenderness in areas where ligaments or tendons attach to bone, such as the back of the heal or sole of the foot
  • Eye inflammation

Learn more about psoriatic arthritis symptoms from the National Institute of Health

Causes and risk factors of psoriatic arthritis

Both men and women are equally at risk for psoriatic arthritis. Experts don't fully understand why the immune system changes to cause this. However, there are some factors that can lead to psoriatic arthritis.

First, the disease may be passed down from biological family members. Researchers have identified some of the genes involved. Secondly, environmental and lifestyle factors may lead to psoriatic arthritis. This can include obesity, stress, infection and injury.

This blog was medically reviewed by William Ridgway, chief of the Division of Rheumatology, Allergy and Clinical Immunology.