What causes arthritis rheumatoid

Content on WhatAnswers is provided "as is" for informational purposes. While we strive for accuracy, we make no guarantees. Content is AI-assisted and should not be used as professional advice.

Last updated: April 4, 2026

Quick Answer: Rheumatoid arthritis (RA) is an autoimmune disease where the body's immune system mistakenly attacks its own healthy tissues, primarily the synovium, the lining of the membranes that surround the joints. This chronic inflammation can lead to joint pain, swelling, stiffness, and eventually, joint damage and deformity.

Key Facts

Rheumatoid arthritis affects approximately 1.3 million adults in the United States.
It is more common in women, with about three times as many women as men developing RA.
RA typically affects smaller joints first, such as those in the hands and feet, before spreading to larger joints.
Symptoms often appear symmetrically, meaning if one knee is affected, the other knee is likely to be affected as well.
While the exact cause is unknown, genetic factors and environmental triggers are believed to play a significant role.

What is Rheumatoid Arthritis?

Rheumatoid arthritis (RA) is a chronic inflammatory disorder that can affect more than just the joints. In some people, the condition also can damage a wide variety of body systems, including the skin, eyes, lungs, heart, and blood vessels. This autoimmune disease occurs when your immune system mistakenly attacks your own body. Specifically, it targets the synovium, a membrane that lines your joints. This membrane produces a fluid that lubricates your joints. In RA, the synovium becomes inflamed, which causes the lining of the joint to thicken into a swollen, abnormal tissue called pannus. This pannus can eventually destroy the cartilage and bone within the joint. The tendons and ligaments that hold the joint together weaken and stretch. Eventually, the joint loses its shape and alignment.

What Causes Rheumatoid Arthritis?

The exact cause of rheumatoid arthritis is still unknown. However, research suggests a combination of factors may contribute to its development:

Genetics

Certain genes can make individuals more susceptible to developing RA. The most significant genetic association is with a gene group called HLA (human leukocyte antigen) class II alleles. Having these genes doesn't guarantee you'll develop RA, but it increases your risk. Researchers believe that in genetically predisposed individuals, certain environmental factors may trigger the disease.

Environmental Triggers

While specific triggers haven't been definitively identified, several environmental factors are being investigated:

Infections: Some viruses and bacteria have been explored as potential triggers, though no conclusive link has been established. The theory is that an infection might initiate an autoimmune response in susceptible individuals.
Smoking: Extensive research has shown a strong link between smoking and an increased risk of developing RA. Smoking also appears to worsen the disease in those who already have it, potentially leading to more severe joint damage. Quitting smoking can help reduce the risk and potentially slow disease progression.
Other Factors: Hormonal factors, particularly in women, are also thought to play a role, given the higher prevalence of RA in females. Factors like childbirth and the use of oral contraceptives have been studied, but their precise impact remains unclear. Obesity has also been identified as a potential risk factor.

The Autoimmune Process

At its core, RA is an autoimmune disease. This means the immune system, which normally defends the body against foreign invaders like bacteria and viruses, malfunctions and begins to attack the body's own healthy tissues. In RA, the immune system targets the synovium, the soft tissue that lines the inside of joints. This leads to chronic inflammation.

Inflammation Cascade

The inflammation in RA is a complex process involving various immune cells and signaling molecules called cytokines. When the immune system mistakenly identifies the synovium as a threat, it sends immune cells to attack it. These cells release inflammatory chemicals that cause:

Swelling (Edema): Fluid buildup in the joint tissues.
Pain: Inflammation irritates nerve endings in the joint.
Redness and Heat: Increased blood flow to the inflamed area.
Stiffness: Swelling and inflammation restrict movement, especially after periods of inactivity.

Over time, this persistent inflammation can erode cartilage, the cushioning tissue between bones in a joint. It can also damage ligaments, tendons, and bone, leading to joint deformity and loss of function.

Who is at Risk?

Several factors increase a person's risk of developing rheumatoid arthritis:

Sex: Women are about two to three times more likely than men to develop RA.
Age: RA can occur at any age, but it most often begins between the ages of 40 and 60.
Family History: If a family member has RA, you may have an increased risk.
Smoking: As mentioned, smoking significantly increases the risk.
Environmental Exposures: Certain occupational exposures to dust or silica may increase risk.
Weight: Being overweight or obese is associated with a higher risk of developing RA.

It's important to remember that having one or more of these risk factors does not mean you will definitely develop RA. Many people with risk factors never develop the condition, while others with no apparent risk factors do.

Living with Rheumatoid Arthritis

While there is no cure for rheumatoid arthritis, early diagnosis and treatment can significantly help manage symptoms, slow disease progression, and improve quality of life. Treatment often involves a combination of medications, physical therapy, occupational therapy, and lifestyle modifications.