Arthritis is inflammation in one or more joints that causes pain, stiffness, and sometimes swelling
Arthritis is not a single disease — it is a group of conditions that all involve joint damage or inflammation. The two most common types are osteoarthritis, which develops when the protective cartilage in a joint wears down over time, and rheumatoid arthritis, which happens when the immune system attacks the lining of the joints. Other types include gout, lupus-related arthritis, and psoriatic arthritis, but osteoarthritis and rheumatoid arthritis account for the majority of cases in older adults.
When you have arthritis, the joint itself becomes inflamed. You may notice pain that gets worse with movement or after sitting still, stiffness especially in the morning, swelling around the joint, or redness and warmth in the skin over the joint. These symptoms can range from mild to severe, and they often come and go — some days are better than others.
Key Takeaways
- Osteoarthritis develops when cartilage wears away inside a joint, usually from years of use or injury.
- Rheumatoid arthritis is an autoimmune condition where the body's immune system attacks joint linings, and it can affect multiple joints at once.
- Common symptoms include joint pain, morning stiffness that lasts more than 30 minutes, swelling, and reduced range of motion.
- Arthritis most often affects the hands, knees, hips, and spine, but can develop in any joint.
- A doctor can diagnose arthritis through physical examination, imaging tests like X-rays, and blood tests for rheumatoid arthritis.
How osteoarthritis develops and progresses
Osteoarthritis is the "wear and tear" type of arthritis. Inside every joint is cartilage — a smooth, slippery tissue that lets bones glide past each other without friction. Over decades, this cartilage can thin and crack. Once it starts to wear, bone rubs against bone, which causes pain and inflammation.
Osteoarthritis usually develops slowly. You might not notice symptoms until you are in your 50s or 60s, even though the cartilage damage may have started years earlier. Risk factors include age, previous joint injury, being overweight (which puts extra stress on weight-bearing joints like the knees and hips), and family history. Osteoarthritis is not reversible, but its progress can be slowed and symptoms can be managed.
How rheumatoid arthritis differs from osteoarthritis
Rheumatoid arthritis (RA) is an autoimmune disease, meaning your immune system mistakenly attacks the synovium — the lining of the joint. This causes inflammation, pain, and eventually can damage the cartilage and bone underneath. Unlike osteoarthritis, RA often affects multiple joints at the same time, usually in a symmetrical pattern (both hands, both knees, both feet).
RA can develop at any age but is more common in people over 60. It tends to come on more suddenly than osteoarthritis, sometimes over weeks or months. People with RA often feel fatigue and general malaise along with joint symptoms. RA is also more likely to run in families. The good news is that early treatment with disease-modifying medications can slow or even stop joint damage, which is why getting a diagnosis quickly matters.
Where arthritis most commonly develops
Arthritis can affect any joint, but certain joints bear more weight or get more use, so they are hit harder. The knees, hips, and lower spine are common sites because they support your body weight. The hands and wrists are also frequently affected, especially in rheumatoid arthritis, which can make everyday tasks like opening jars or buttoning shirts difficult.
The neck and feet are other common trouble spots. Arthritis in the neck can cause pain and stiffness that radiates into the shoulders. Arthritis in the feet and ankles can make walking painful and affect your balance. Some people develop arthritis in just one or two joints, while others have it in many places at once.
Symptoms that signal arthritis may be developing
The hallmark symptoms of arthritis are joint pain, stiffness, and swelling. Pain may be sharp or dull, constant or intermittent. Stiffness is often worst in the morning or after you have been sitting still — it usually improves as you move around and warm up the joint. Swelling can make a joint look puffy or feel warm to the touch.
You might also notice that a joint does not move through its full range of motion, or that certain movements cause a grinding or clicking sensation. Some people describe a feeling of instability, as if the joint might give way. If symptoms last more than a few weeks, involve multiple joints, or are accompanied by fatigue or fever, it is worth mentioning to your doctor. Early diagnosis and treatment can make a real difference in how well you manage the condition.
What happens inside a joint when arthritis develops
To understand arthritis, it helps to know basic joint anatomy. A joint is where two bones meet. The ends of the bones are covered with cartilage, a smooth tissue that reduces friction. The joint is enclosed in a capsule lined with synovium, which produces fluid that lubricates the joint. Ligaments and tendons hold everything in place and allow movement.
In osteoarthritis, the cartilage surface breaks down and becomes rough. Bone spurs (osteophytes) may form at the edges of the joint. The synovial fluid may become thinner and less effective at cushioning. In rheumatoid arthritis, the synovium becomes inflamed and thickened, producing excess fluid and releasing chemicals that attack cartilage and bone. Over time, this can erode the joint structure itself.
Why arthritis pain and stiffness feel worse at certain times
Many people with arthritis notice their symptoms follow patterns. Morning stiffness is extremely common — after hours of inactivity, the joint fluid has not been circulating, and the muscles around the joint have tightened. Moving around and gentle activity usually helps loosen things up within 30 minutes to an hour.
Cold, damp weather often makes arthritis worse, though doctors are still studying exactly why. Some people find that high activity the day before leads to increased pain the next day — a pattern called a "flare." Stress and poor sleep can also worsen symptoms. Learning your own patterns helps you plan your day: you might schedule important tasks for times when your joints typically feel better, or use heat or ice strategically to manage pain before it peaks.
Frequently Asked Questions
Is arthritis the same as normal aging?
No. While some joint changes happen with age, arthritis is a specific condition involving inflammation or cartilage damage that causes pain and limits movement. Many people in their 70s and 80s have no arthritis at all. Aging and arthritis are not the same thing.
Can you catch arthritis from someone else?
No, arthritis is not contagious. Osteoarthritis develops from wear and tear, and rheumatoid arthritis is an autoimmune condition. Neither can be passed from one person to another through contact or any other means.
Does arthritis always get worse over time?
Osteoarthritis typically progresses slowly, but the rate varies widely — some people have minimal change over years, while others notice faster decline. Rheumatoid arthritis can be slowed or even halted with early treatment using disease-modifying drugs. In both cases, staying active and managing symptoms can help preserve joint function.
What is the difference between arthritis and joint pain?
Joint pain can have many causes — a recent injury, overuse, or muscle strain — and may go away on its own. Arthritis is a chronic condition where the joint itself is damaged or inflamed, causing ongoing or recurring pain. If joint pain lasts more than a few weeks or involves swelling and stiffness, it warrants a doctor's evaluation.
Can you have arthritis without pain?
Some people have arthritis visible on X-rays but experience little or no pain, especially in the early stages of osteoarthritis. Others have significant pain with minimal visible damage. Pain level does not always match the degree of joint damage, which is why imaging and a physical exam are both important for diagnosis.