Arthritis describes over 100 conditions that involve inflammation and damage in the joints, the tissues around the joint, and other connective tissues. Osteoarthritis, rheumatoid arthritis, and psoriatic arthritis are three common types.

Arthritis affects 54 million adults in the United States, which is about 1 in 5 people. It is more common among adults 65 years or older. However, it can affect people of all ages, including children.

This article discusses the different types of arthritis, what causes it, the symptoms, and possible treatments.

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Arthritis refers to more than 100 rheumatic diseases and conditions that affect joints. These conditions tend to involve pain, aching, stiffness, and swelling in and around one or more joints.

The word “arthritis” means joint inflammation. However, inflammation may also affect the tendons and ligaments surrounding the joint. The symptoms can develop gradually or suddenly and may impair a person’s ability to perform everyday tasks.

The arthritis symptoms a person has and how they appear can vary depending on the type.

Symptoms can develop gradually or suddenly. Because arthritis is most often a chronic (long-term) disease, symptoms may come and go or persist over time.

However, anyone who experiences any of the following four key symptoms should visit a doctor:

  1. Pain: Pain from arthritis can be constant or come and go. It may affect only one body part or several.
  2. Swelling: In some types of arthritis, the skin over the affected joint may become red and swollen and feel warm to the touch. Redness may be less obvious on dark skin tones.
  3. Stiffness: Stiffness is a typical symptom. With some types, stiffness is most likely upon waking up in the morning or after sitting at a desk or in a car for a long time. With other types, stiffness may occur after exercise or be persistent.
  4. Difficulty moving a joint: If moving a joint or getting up from a chair is hard or painful, this could indicate arthritis or another joint problem.

In addition to these general symptoms, certain types of arthritis may cause their own symptoms.

For example, juvenile RA can cause eye problems, including uveitis, iridocyclitis, or iritis. Septic arthritis often causes fever and intense joint pain. It can become an emergency if it progresses to sepsis.

There are more than 100 types of arthritis. Arthritis is categorized into the following types:

Inflammatory arthritis

Inflammation is a normal part of the body’s healing process. It tends to occur as a defense against viruses and bacteria or as a response to injuries, such as burns.

However, with inflammatory arthritis, inflammation occurs in people for no apparent reason and not as a normal reaction to injury or infection. This type of inflammation is unhelpful and damages the affected joints, resulting in pain, stiffness, and swelling.

Inflammatory arthritis can affect several joints. The inflammation can damage the surface of the joints and also the underlying bone.

Examples of inflammatory arthritis include:

Degenerative or mechanical arthritis

Degenerative or mechanical arthritis refers to a group of conditions that mainly involve damage to the cartilage that covers the ends of the bones.

The main job of the smooth, slippery cartilage is to help the joints glide and move smoothly. This type of arthritis causes the cartilage to become thinner and rougher.

To compensate for the loss of cartilage and changes in joint function, the body begins to remodel the bone in an attempt to restore stability. This can cause undesirable bony growths to develop, called osteophytes. The joint can become misshapen. This condition is commonly called osteoarthritis (OA).

OA can also result from previous damage to the joint, such as a fracture or previous inflammation in the joint.

Connective tissue disease (CTD)

Connective tissues, such as tendons, ligaments, and cartilage, support, bind together, or separate other body tissues and organs.

CTD involves joint pain and inflammation, which may occur in other tissues, including the skin, muscles, lungs, and kidneys. This can result in various symptoms besides painful joints and may require consultation with several specialists.

Examples of CTD include:

Infectious arthritis

A bacterium, virus, or fungus that enters a joint can sometimes cause inflammation.

Infectious conditions that can infect joints include:

A doctor can treat a joint infection with antibiotics or other antimicrobial medication. However, if the infection has persisted for some time, the arthritis can sometimes become chronic, and joint damage may be irreversible.

Metabolic arthritis

Uric acid is a chemical created when the body breaks down substances called purines. Purines are present in human cells and several foods.

Most uric acid dissolves in blood and travels to the kidneys. From there, it passes out of the body in urine. Some people have high uric acid levels because they either naturally produce more than they need or their body cannot clear the uric acid quickly enough.

Uric acid builds up and accumulates in some people and forms needle-like crystals in the joint, resulting in sudden spikes of extreme joint pain or a gout flareup.

Gout can either come and go in episodes or become chronic if uric acid levels do not decrease.

It commonly affects a single joint or a small number of joints, such as the big toe and hands. It usually affects the extremities. One theory is that uric acid crystals form in cooler joints, away from the body’s main warmth.

Childhood arthritis

Childhood arthritis can refer to several types of arthritis. Juvenile idiopathic arthritis (JIA), also known as juvenile rheumatoid arthritis (JRA), is the most common type.

Arthritis in childhood can cause permanent damage to joints. While there is no current cure, remission is possible. This is when the disease is inactive.

The cause of childhood arthritis is unknown but is likely due to immune system problems.

Septic arthritis

Septic arthritis is joint inflammation caused by a bacterial or fungal infection. It commonly affects the knee and hip. Around 2 to 6 per 100,000 people experience septic arthritis.

It may develop when bacteria or other disease-causing microorganisms spread through the blood to a joint or when the joint is directly infected with a microorganism through injury or surgery.

Bacteria such as Staphylococcus, Streptococcus, or Neisseria gonorrhoeae cause most cases of acute septic arthritis. Organisms such as Mycobacterium tuberculosis and Candida albicans cause chronic septic arthritis. This is less common than acute (short-term) septic arthritis.

The following conditions increase the risk of developing septic arthritis:

  • existing joint disease or damage
  • artificial joint implants
  • bacterial infection elsewhere in the body
  • presence of bacteria in the blood
  • chronic illness or disease, such as diabetes, RA, and sickle cell disease
  • intravenous (IV) or injection drug use
  • medications that suppress the immune system
  • recent joint injury
  • recent joint arthroscopy or other surgery
  • conditions that weaken the immune system, such as HIV
  • older age

Septic arthritis is a rheumatologic emergency. It can lead to rapid joint destruction and be fatal.

There is no single cause of all types of arthritis. The cause or causes vary according to the type or form of arthritis.

Possible causes may include:

Most types of arthritis are due to a combination of factors. However, some have no obvious cause and appear unpredictably.

Treatment for arthritis aims to control pain, minimize joint damage, and improve or maintain function and quality of life. A range of medications and lifestyle measures can help achieve this and protect joints from further damage.

The exact treatment depends on the type of arthritis a person develops. It may involve:

Medication

Medications a doctor prescribes depend on the type of arthritis. Commonly used drugs include:

  • Analgesics: These drugs reduce pain. However, they have no effect on inflammation. Examples include acetaminophen (Tylenol) and tramadol (Ultram).
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs reduce both pain and inflammation. NSAIDs are available over the counter and include ibuprofen (Advil, Motrin IB) and naproxen (Aleve). NSAIDs are available as creams, gels, or patches that can be applied to specific joints.
  • Counterirritants: Some creams and ointments contain menthol or capsaicin, the ingredient that makes hot peppers spicy. Rubbing these on the skin over a painful joint can soften pain signals from the joint and lessen pain.
  • Disease-modifying antirheumatic drugs (DMARDs): These commonly treat RA. DMARDs slow or stop the immune system from attacking the joints. Examples include methotrexate (Trexall) and hydroxychloroquine (Plaquenil).
  • Biologics: These are genetically engineered drugs that target various protein molecules involved in the immune response. Examples include etanercept (Enrebel) and infliximab (Remicade).
  • Corticosteroids: Prednisone and cortisone reduce inflammation and suppress the immune system.

Surgery

Depending on the type of arthritis a person has, different surgical treatments on the affected joints may be necessary. Doctors may recommend surgery when a person’s symptoms are severe and other treatments have not provided relief.

Surgical options for arthritis include:

Learn more about surgery for arthritis.

People can take steps to reduce or prevent arthritis.

Avoiding smoking and limiting alcohol can help prevent joint inflammation. Eating a nutritious, balanced diet, getting regular physical activity, and taking certain herbal supplements may help.

Diet

Eating some types of food may help reduce inflammation.

The following foods, found in a Mediterranean diet, can provide many nutrients that benefit joint health and may help relieve joint inflammation:

On the other hand, some foods may worsen arthritis inflammation. Doctors recommend people living with arthritis to avoid or limit:

  • processed foods
  • foods that contain added sugar
  • refined carbohydrates

Learn more about diet and arthritis.

Physical activity

Regular physical activity is important in maintaining joint flexibility and reducing stiffness. However, people may experience short-term increases in pain when first beginning exercise.

People with arthritis can participate in joint-friendly physical activity on their own or with friends. As many people with arthritis have other conditions, such as heart disease, it is important to choose appropriate activities, such as:

Herbal medicines

A number of herbal supplements may benefit people with arthritis. According to a 2020 review of research, some herbal supplements may help relieve pain and inflammation or help reduce the need for taking pain medications. These include:

However, anyone considering using natural remedies for any type of arthritis should speak with a doctor first. Some supplements may negatively interact with prescription medications.

There are more than 100 types of arthritis.

Some types, such as RA and lupus, are caused by an overactive immune system and affect multiple organs. Other types are due to physical degeneration in specific joints.

Arthritis may develop due to injury, immune system dysfunction, genetic makeup, and other factors.

A doctor can help a person determine whether they have arthritis and the best course of treatment. Treatments can include medications and lifestyle strategies. In severe cases, a person may need surgery.