Arthritis is inflammation in one or more joints that causes pain, stiffness, and swelling. It isn’t a single disease. The term covers more than 100 different conditions that affect the joints and surrounding tissues, ranging from wear-and-tear damage to autoimmune attacks to crystal buildup. About 21.3% of U.S. adults have been diagnosed with some form of arthritis, making it one of the most common chronic conditions in the country.
The Two Most Common Types
Most people with arthritis have one of two forms: osteoarthritis or rheumatoid arthritis. They feel similar on the surface, but they have very different causes and require different approaches.
Osteoarthritis is the most common type. It happens when the cartilage that cushions the ends of your bones gradually wears down. Without that smooth buffer, bones rub closer together, producing pain, stiffness, and reduced range of motion. It tends to develop slowly over years, often showing up first in joints you’ve used heavily or injured in the past: knees, hips, hands, and the spine. Osteoarthritis is primarily a mechanical problem, not an immune system problem.
Rheumatoid arthritis works differently. It’s an autoimmune condition where your immune system mistakenly attacks the lining of your joints, causing inflammation that can eventually damage cartilage and bone. It typically begins insidiously, with symptoms building over weeks to months. Fatigue, general malaise, and even depression often appear before any joint pain does. Rheumatoid arthritis tends to affect smaller joints first (the knuckles and the base of the toes) and frequently appears symmetrically, meaning both hands or both knees at the same time.
Other Forms Worth Knowing
Crystal-induced arthritis includes gout and pseudogout. Gout develops when excess uric acid forms sharp crystals inside a joint, most famously the big toe. Pseudogout involves a different type of crystal, made from calcium and pyrophosphate, and it more commonly strikes the knee or wrist. Both cause sudden, intense flare-ups of pain and swelling that can be debilitating, then subside between episodes. The two conditions can look nearly identical during a flare, which is why doctors sometimes need to examine joint fluid under a microscope to tell them apart.
Children get arthritis too. Juvenile idiopathic arthritis (JIA) is the most common form in kids, and it can run in families. Beyond joint swelling and stiffness, children with JIA are at risk for eye inflammation that may not cause obvious symptoms early on, so regular eye exams with a specialist are part of ongoing care. Doctors diagnose JIA through a combination of physical examination, blood tests for inflammation markers and specific antibodies, and imaging like ultrasound or X-rays.
Other types include psoriatic arthritis (linked to the skin condition psoriasis), ankylosing spondylitis (which primarily affects the spine), and arthritis triggered by infections like Lyme disease, staph infections, or gonorrhea.
What Arthritis Feels Like Early On
The earliest signs depend on the type. Osteoarthritis usually starts as an aching stiffness that’s worse after inactivity or at the end of a long day. The stiffness loosens up within about 30 minutes of moving around.
Rheumatoid arthritis has a more distinctive early pattern. Morning stiffness lasts longer, often more than an hour and sometimes several hours. You might notice puffiness in the small joints of the hands, particularly the middle knuckles and the ones at the base of the fingers. Inflamed joints sometimes feel warm to the touch. Squeezing across the knuckles or the ball of the foot and feeling pain is one of the most sensitive early indicators of joint inflammation.
In both types, the stiffness and soreness tend to creep in gradually. People often attribute the discomfort to overuse or aging before recognizing it as arthritis.
How Doctors Determine the Type
No single test confirms arthritis on its own. Doctors piece together a picture from your symptoms, a physical exam, blood work, and imaging.
Blood tests help distinguish inflammatory types from wear-and-tear damage. The main ones include:
- Inflammation markers (ESR and CRP): These measure how much inflammation is active in your body. They’re often elevated in rheumatoid arthritis but aren’t specific to it.
- Rheumatoid factor (RF): An antibody found in many people with rheumatoid arthritis, though not everyone with the disease tests positive.
- Anti-CCP antibodies: A more specific marker for rheumatoid arthritis that can sometimes be detected early in the disease.
- Complete blood count: Helps rule out other conditions and can reveal anemia, which sometimes accompanies chronic inflammatory arthritis.
X-rays are typically ordered first to check for bone damage, fractures, or other causes of joint pain. Ultrasound can detect fluid and inflammation in a joint before any damage shows on an X-ray, making it especially useful for catching things early. MRI provides the most detailed images and helps doctors track how the condition progresses over time.
What Increases Your Risk
Different types of arthritis have different risk profiles, but several factors overlap.
Family history matters most for autoimmune forms. Rheumatoid arthritis, lupus-related arthritis, and ankylosing spondylitis all have genetic components. Having a close relative with one of these conditions raises your likelihood of developing it.
Excess weight is one of the strongest modifiable risk factors for osteoarthritis, particularly in the knees. Every extra pound adds roughly four pounds of pressure across the knee joint with each step, so the cumulative effect is significant. Jobs that require repetitive bending, squatting, or kneeling also increase osteoarthritis risk over time. A prior joint injury, like a torn ACL, makes osteoarthritis more likely in that same joint years later, even if the injury healed well.
Smoking raises the risk of developing rheumatoid arthritis and tends to make the disease more severe once it starts. Military veterans have higher rates of arthritis overall, likely connected to the physical demands and injuries of service.
How Arthritis Is Managed
Treatment depends entirely on the type. Osteoarthritis management focuses on protecting the joint and managing pain, while inflammatory types like rheumatoid arthritis require treatments that calm the immune system.
For rheumatoid arthritis, the goal is to reach remission or at least low disease activity as early as possible, because unchecked inflammation causes permanent joint damage. Treatment typically starts with a disease-modifying drug (the most common first choice slows the immune response broadly) combined with a short course of a steroid to control symptoms while the slower-acting drug takes effect over three to six months. If that combination isn’t enough, doctors move to biologic therapies that target specific parts of the immune system driving the inflammation, or newer oral medications that block inflammatory signaling pathways inside cells.
For osteoarthritis, the mainstays are non-drug approaches. Losing weight, if you carry extra, is one of the most effective things you can do. Joint pain often decreases meaningfully after weight loss, though the relationship isn’t always straightforward. Strengthening the muscles around an affected joint takes pressure off the joint itself. Low-impact activities like swimming, cycling, and walking are consistently helpful. Over-the-counter anti-inflammatory pain relievers can manage flares, and physical therapy helps improve movement patterns that reduce stress on damaged joints.
Gout management works differently again. During an acute flare, the priority is controlling the intense pain and inflammation. Long-term, the focus shifts to lowering uric acid levels in the body so crystals stop forming. Dietary changes help, but most people with recurrent gout also need medication to bring uric acid down to a safe range.
Living With Arthritis Long Term
Arthritis is typically a lifelong condition, but “lifelong” doesn’t have to mean “always getting worse.” Many people with rheumatoid arthritis achieve remission with modern treatments, especially when diagnosed and treated early. Osteoarthritis progresses more slowly in people who stay active, maintain a healthy weight, and avoid repeatedly overloading affected joints.
Regular physical activity is the single most consistently beneficial thing across all types of arthritis. People who exercise regularly report significantly less pain and better function than those who don’t. The instinct to rest a painful joint is understandable, but prolonged inactivity makes stiffness, weakness, and pain worse over time. The key is choosing activities that load the joint gently rather than avoiding movement altogether.