Rheumatoid arthritis (RA) is a chronic autoimmune disease in which the immune system mistakenly attacks the lining of the joints, causing pain, swelling, and stiffness. As of 2019, roughly 18 million people worldwide were living with RA, and about 70% of them are women. Unlike osteoarthritis, which results from wear and tear on cartilage, RA is driven by inflammation that can affect the entire body.
How RA Develops in the Body
In a healthy joint, a thin tissue called the synovial membrane produces fluid that keeps everything moving smoothly. In RA, the immune system loses its ability to distinguish this tissue from a foreign invader and launches an inflammatory attack against it. What makes RA particularly tricky is that this immune system malfunction begins long before symptoms appear. Specific antibodies associated with RA can be detected in the blood years before a person ever feels joint pain.
Once inflammation takes hold in the synovial membrane, it feeds on itself. Immune cells flood the joint lining, and the tissue thickens into a destructive mass called pannus. This tissue sits at the boundary between the joint lining, cartilage, and bone, releasing enzymes that gradually erode both. Without treatment, this cycle of inflammation and tissue destruction continues and becomes irreversible.
Early Symptoms to Recognize
The hallmark of RA is pain, swelling, and stiffness in the same joints on both sides of the body. If your left wrist is affected, your right wrist likely is too. This symmetrical pattern is one of the features that distinguishes RA from other forms of arthritis. The small joints of the hands and feet are often the first to be involved.
Morning stiffness is another telling sign. In RA, stiffness after waking typically lasts longer than one hour, sometimes several hours. By contrast, the stiffness from osteoarthritis usually eases within 30 to 60 minutes. Beyond the joints, RA can cause fatigue, low-grade fever, weakness, and a general feeling of being unwell. Many people dismiss these early symptoms as normal aging or overuse, which can delay diagnosis.
How RA Is Diagnosed
There is no single test that confirms RA. Doctors use a scoring system developed jointly by the American College of Rheumatology and the European League Against Rheumatism that evaluates four areas: how many joints are involved and which ones, whether specific antibodies are present in the blood, whether blood markers of inflammation are elevated, and how long symptoms have lasted. A score of 6 or higher out of 10 points to a definite RA diagnosis.
This system was designed to catch the disease early, before it causes visible joint damage. Older diagnostic criteria relied on features of advanced disease like joint erosion on X-rays, which meant many people weren’t diagnosed until significant damage had already occurred.
Effects Beyond the Joints
RA is not just a joint disease. The same inflammatory process that attacks the synovial membrane can affect organs throughout the body, particularly in people with long-standing or poorly controlled disease.
- Lungs: Inflammation of the lung lining (pleuritis) affects 5% to 10% of people with RA, and clinically significant lung scarring occurs in roughly 8% to 12% of cases. Lung nodules can also form, which sometimes need to be distinguished from cancer on imaging.
- Heart: Pericarditis, an inflammation of the sac surrounding the heart, is the most common cardiac complication and can occasionally be the first sign of RA. The chronic inflammation of RA also accelerates the buildup of plaque in arteries, raising the risk of heart attack.
- Eyes: At least 10% of people with RA develop dry eyes, often as part of a secondary condition called Sjögren’s syndrome. More serious eye inflammation affecting the white of the eye (scleritis) can also occur.
Most of these complications are more common in people who test positive for RA antibodies in their blood and who have higher overall disease activity.
Treatment and What to Expect
The goal of modern RA treatment is to stop joint damage before it starts. This means starting medication early, ideally within months of symptom onset. The first-line treatment for most people with moderate to high disease activity is a class of drugs called disease-modifying antirheumatic drugs (DMARDs), with methotrexate being the most commonly recommended starting point. For milder disease, hydroxychloroquine is sometimes used instead.
If the initial medication doesn’t bring the disease under adequate control, doctors can add or switch to biologic therapies. These are injectable or infused medications that target specific parts of the immune system driving the inflammation, such as proteins involved in the inflammatory cascade or particular types of immune cells. A newer class of oral medications called JAK inhibitors offers another option for people who don’t respond well to earlier treatments.
Remission, meaning minimal or no disease activity, is achievable for a meaningful number of people. In clinical trials, roughly 30% of people with early RA and 15% to 20% of those with more established disease reach remission with current therapies. Even when full remission isn’t achieved, modern treatment can substantially reduce joint damage and improve daily function compared to earlier decades.
Diet and Lifestyle Factors
Diet alone won’t replace medication, but there is real clinical evidence that certain eating patterns can reduce RA-related pain. A meta-analysis of seven randomized controlled trials found that anti-inflammatory diets lowered pain scores significantly compared to standard diets.
The Mediterranean diet has the strongest evidence base. Its emphasis on fish (rich in omega-3 fatty acids), vegetables, fruits, and whole grains while limiting red meat and processed foods helps shift the body’s inflammatory balance. Omega-3s from fish oil compete with a pro-inflammatory fatty acid called arachidonic acid, which is abundant in red meat and is a key driver of joint inflammation. Vegetarian and vegan diets show similar benefits, partly because they contain very little arachidonic acid.
High-fiber diets also play a role by feeding beneficial gut bacteria. In people with RA, a high-fiber diet has been shown to increase anti-inflammatory compounds produced by gut microbes while decreasing inflammatory signaling molecules. Regular physical activity, particularly low-impact exercise like swimming, cycling, and walking, helps maintain joint flexibility and muscle strength without worsening inflammation.
RA Compared to Osteoarthritis
Because both conditions cause joint pain and stiffness, RA and osteoarthritis are often confused. The differences matter because they require completely different treatment approaches. Osteoarthritis is a mechanical problem: cartilage wears down over time, typically in weight-bearing joints like the knees and hips or in joints that have been injured. It tends to affect one side of the body more than the other and worsens with activity.
RA is an immune system problem that causes inflammation first, with joint damage following as a consequence. It favors smaller joints (hands, wrists, feet), affects both sides symmetrically, and causes prolonged morning stiffness lasting well over an hour. RA also produces systemic symptoms like fatigue and fever that osteoarthritis does not. Women are two to three times more likely than men to develop RA, and it commonly appears between ages 30 and 60, while osteoarthritis is more closely tied to age and joint use over a lifetime.