Rheumatoid arthritis is what doctors call an autoimmune condition. It starts when your immune system, which is supposed to protect you, goes awry and begins to attack your body’s own tissues. It causes inflammation in the lining of your joints (the synovium). As a result, your joints may get red, warm, swollen, and painful.

RA affects joints on both sides of the body, such as both hands, both wrists, or both knees. This symmetry helps to set it apart from other types of arthritis. Over time, RA can affect other body parts and systems, from your eyes to your heart, lungs, skin, blood vessels, and more.

The warning signs of RA are:

• Joint pain and swelling
• Stiffness, especially in the morning or after you sit for a long time
• Fatigue

Rheumatoid arthritis affects everyone differently. For some, joint symptoms happen gradually over several years. In others, it may come on quickly.

Some people may have rheumatoid arthritis for a short time and then go into remission, which means they don’t have symptoms.

Anyone can get RA. It affects about 1% of Americans.

The disease is 2 to 3 times more common in women than in men, but men tend to have more severe symptoms.

It usually starts in middle age. But young children and the elderly also can get it.

Doctors don’t know the exact cause. Something seems to trigger the immune system to attack your joints and, sometimes, other organs. Some experts think a virus or bacteria may change your immune system, causing it to attack your joints. Other theories suggest that in some people, smoking may lead to rheumatoid arthritis.

Certain genetic patterns may make some people more likely to get RA than others.

Immune system cells move from the blood into your joints and the tissue that lines them. This is called the synovium. Once the cells arrive, they create inflammation. This makes your joint swell as fluid builds up inside it. Your joints become painful, swollen, and warm to the touch.

Over time, the inflammation wears down the cartilage, a cushy layer of tissue that covers the ends of your bones. As you lose cartilage, the space between your bones narrows. As time goes on, they could rub against each other or move out of place. The cells that cause inflammation also make substances that damage your bones.

The inflammation in RA can spread and affect organs and systems throughout your body, from your eyes to your heart, lungs, kidneys, blood vessels, and even your skin.

There is no single test that shows whether you have RA. Your doctor will give you a checkup, ask you about your symptoms, and possibly perform X-rays and blood tests.

Rheumatoid arthritis is diagnosed from a combination of things, including:

• The location and symmetry of painful joints, especially the hand joints
• Joint stiffness in the morning
• Bumps and nodules under the skin (rheumatoid nodules)
• Results of X-rays and blood tests

In addition to checking for joint problems, your doctor will also do blood tests to diagnose RA. She’ll be looking for:

Anemia: People with rheumatoid arthritis may have a low number of red blood cells.

C-reactive protein (CRP): High levels are also signs of inflammation.

Some people with rheumatoid arthritis may also have a positive antinuclear antibody test (ANA), which indicates an autoimmune disease, but the test does not specify which autoimmune disease.

Cyclic citrulline antibody test (anti-CCP): This more specific test checks for anti-CCP antibodies, which suggest you might have a more aggressive form of rheumatoid arthritis.

Erythrocyte sedimentation rate (ESR): How fast your blood clumps up in the bottom of a test tube shows there may be inflammation in your system.

Rheumatoid factor (RF): Most, but not all, people with rheumatoid arthritis have this antibody in their blood. But it can show up in people who don’t have RA.

Treatments include medications, rest, exercise, and, in some cases, surgery to correct joint damage.

Your options will depend on several things, including your age, overall health, medical history, and how severe your case is.

Many rheumatoid arthritis medications can ease joint pain, swelling, and inflammation. Some of these drugs prevent or slow down the disease.

Drugs that ease joint pain and stiffness include:

• Anti-inflammatory painkillers, like aspirin, ibuprofen, or naproxen
• Pain relievers that you rub on your skin
• Corticosteroids, like prednisone
• Narcotic pain relievers

Your doctor may also give you strong medications called disease-modifying antirheumatic drugs (DMARDs). They work by interfering with or suppressing your immune system’s attack on your joints.

Traditional DMARDs are often the first-line treatment for RA:

• Hydroxychloroquine (Plaquenil), which was created to treat malaria
• Methotrexate (Rheumatrex, Trexall), which was first developed to treat cancer
• Leflunomide (Arava)
• Sulfasalazine (Azulfidine)

Biologic response modifiers are man made versions of proteins in human genes. They’re an option if your RA is more severe, or if DMARDs didn’t help. You might even take a biologic and a DMARD together. The doctor could also give you a biosimilar. These new drugs are near-exact copies of biologics that cost less. Biologics approved for RA include:

You need to be active, but you also have to pace yourself. During flare-ups, when inflammation gets worse, it’s best to rest your joints. Using a cane or joint splints can help.

When the inflammation eases, it’s a good idea to exercise. It’ll keep your joints flexible and strengthen the muscles that surround them. Low-impact activities, like brisk walking or swimming, and gentle stretching can help. You may want to work with a physical therapist at first.

When joint damage from rheumatoid arthritis has become severe, surgery may help.

Although there isn’t a cure for rheumatoid arthritis, early, aggressive treatment will help prevent disability and increase your chances of remission.