The main causes of arthritis differ by type

Arthritis develops through different pathways depending on which type you have. Osteoarthritis happens when the cartilage that cushions your joints wears down over time — usually from decades of use, injury, or extra weight on your joints. Rheumatoid arthritis is an autoimmune disease, meaning your immune system mistakenly attacks the lining of your joints. Other forms like gout result from uric acid crystals building up in joints, while lupus and other systemic diseases can cause arthritis as part of a broader condition affecting multiple body systems.

You do not need to have done anything "wrong" to develop arthritis. Some people get it from their genes, some from an old injury that never fully healed, some from their body's immune response, and some straightforward from the passage of time. Understanding which type you have matters because the cause shapes how doctors treat it and what you can do to slow it down.

Key Takeaways

  • Osteoarthritis comes from cartilage wearing away, usually over many years, and is the most common type in older adults.
  • Rheumatoid arthritis is caused by your immune system attacking joint linings and often runs in families.
  • Previous injuries, excess weight, and repetitive stress on joints all increase your risk of developing arthritis.
  • Some forms of arthritis like gout and lupus-related arthritis stem from different causes entirely and require different treatment approaches.
  • Age, family history, and sex (women are more likely to develop rheumatoid arthritis) are risk factors you cannot change, but lifestyle choices can still matter.

How osteoarthritis develops from wear and tear

Osteoarthritis is the result of your joints straightforward wearing out. The cartilage covering the ends of your bones is smooth and slippery, allowing bones to glide past each other without friction. Over decades, this cartilage gradually thins and roughens. Once it wears thin enough, bone starts rubbing against bone, causing pain, stiffness, and swelling.

This process usually takes years or decades. You might not notice anything until the damage is already significant. Osteoarthritis most commonly affects the knees, hips, hands, and spine — the joints that bear weight or get used repeatedly. It is far more common than rheumatoid arthritis and becomes increasingly likely as you age, though age alone does not may provide you will develop it.

Certain factors speed up this wear. Extra weight puts more stress on weight-bearing joints like your knees and hips. A previous injury — even one from years ago — can damage cartilage in ways that lead to arthritis later. Repetitive motions from work or sports can also wear joints faster. Some people's cartilage straightforward breaks down more quickly due to their genes.

How rheumatoid arthritis develops from immune system attacks

Rheumatoid arthritis happens when your immune system mistakenly identifies the lining of your joints as a threat and attacks it. This lining, called the synovium, becomes inflamed and swollen. Over time, this inflammation can damage the cartilage and bone underneath. Unlike osteoarthritis, which develops slowly from mechanical wear, rheumatoid arthritis can develop relatively quickly and often affects multiple joints at once, usually on both sides of your body.

Doctors do not fully understand why the immune system turns against your own joints in some people and not others. Genetics play a role — if a close relative has rheumatoid arthritis, your risk is higher. Certain infections may also trigger the condition in people who are genetically susceptible. Women are two to three times more likely than men to develop rheumatoid arthritis, suggesting hormones may be involved.

Rheumatoid arthritis typically appears between ages 30 and 60, though it can start at any age. It is often more aggressive than osteoarthritis and can cause permanent joint damage if not treated early. This is why doctors recommend starting treatment as soon as possible after diagnosis.

Other causes: gout, lupus, and systemic diseases

Gout develops when uric acid builds up in your blood and forms needle-like crystals in your joints. Your body produces uric acid when it breaks down purines, substances found in red meat, organ meats, certain seafood, and alcohol. Some people's bodies produce too much uric acid, while others cannot filter it out efficiently through their kidneys. Gout typically strikes suddenly in one joint, most often the big toe, and causes severe pain and swelling.

Lupus and other systemic autoimmune diseases can cause arthritis as part of a broader condition affecting skin, kidneys, heart, and other organs. Psoriatic arthritis develops in some people who have psoriasis, a skin condition. These forms of arthritis stem from the same kind of immune system malfunction as rheumatoid arthritis but occur alongside other symptoms.

Infections can also trigger arthritis. Lyme disease, spread by tick bites, can cause joint pain and swelling. Some viral infections may lead to temporary arthritis that resolves on its own. A few bacterial infections can cause permanent joint damage if not treated promptly.

Risk factors you cannot change

Age is the strongest risk factor for osteoarthritis. Your cartilage straightforward has more time to wear down the older you are. Most people over 65 have some osteoarthritis, though not everyone has symptoms.

Family history matters for both osteoarthritis and rheumatoid arthritis. If your parents or siblings developed arthritis, your own risk is higher. Genes influence how your cartilage breaks down, how your immune system functions, and how your body handles inflammation.

Sex affects your risk. Women are more likely to develop rheumatoid arthritis and lupus-related arthritis. After menopause, women's risk of osteoarthritis increases, possibly because of changes in estrogen levels.

Risk factors you can influence

Weight directly affects your joints. Extra pounds put more stress on knees, hips, and ankles. Losing weight, even 5 to 10 pounds, can reduce pain and slow the progression of osteoarthritis in weight-bearing joints. Weight also affects inflammation throughout your body, which matters for rheumatoid arthritis and other inflammatory types.

Activity level cuts both ways. Repetitive stress from certain jobs or sports can wear joints faster. At the same time, staying sedentary weakens the muscles that support and protect your joints, making arthritis worse. Low-impact movement like walking, swimming, or water aerobics strengthens muscles without grinding your joints.

Injury to a joint increases the risk that arthritis will develop there later, even years after the injury heals. This is why people who have torn cartilage, broken bones in a joint, or severe sprains sometimes develop arthritis in that joint sooner than in others.

Diet may influence arthritis risk and progression. Some research suggests that foods high in omega-3 fatty acids (fish, walnuts, flaxseed) and antioxidants (berries, leafy greens) may reduce inflammation. Alcohol, especially in excess, can trigger gout attacks and may worsen rheumatoid arthritis in some people.

When to talk with your doctor about arthritis causes

If you have been diagnosed with arthritis, ask your doctor which type you have and what caused it in your case. This matters because the cause shapes your treatment options. For osteoarthritis, your doctor may focus on weight management, exercise, and pain relief. For rheumatoid arthritis, early treatment with medications that slow immune system activity can prevent permanent damage.

Tell your doctor about any family history of arthritis, previous injuries to the affected joint, your job or hobbies that involve repetitive motions, and your current weight and activity level. This information helps your doctor understand your individual risk factors and recommend steps that may slow progression.

If you develop sudden, severe joint pain and swelling — especially if it affects one joint or comes with fever — seek care promptly. This could indicate gout, infection, or another condition requiring when ready treatment.

Frequently Asked Questions

Can arthritis be prevented if it runs in my family?

You cannot change your genes, but you can reduce your risk by maintaining a healthy weight, staying active, protecting your joints from injury, and eating a diet rich in anti-inflammatory foods. If a close relative has rheumatoid arthritis, talk with your doctor about whether monitoring for early signs makes sense for you.

Does arthritis always get worse over time?

Osteoarthritis typically progresses slowly, but the rate varies widely. Some people have minimal symptoms for years, while others experience faster changes. Rheumatoid arthritis can progress quickly if untreated, but modern medications can slow or even stop progression if started early. Gout can be managed so attacks become rare or stop entirely.

If I had a knee injury years ago, will I definitely get arthritis?

Not necessarily. A previous injury increases your risk, but many people with old injuries never develop arthritis in that joint. Keeping the joint strong through exercise, maintaining a healthy weight, and avoiding re-injury can help protect it.

Does my job cause arthritis?

Repetitive motions and stress on joints from certain jobs can speed up wear and tear, but they rarely cause arthritis entirely on their own. Your genes, age, weight, and overall health also matter. If your job involves heavy lifting or repetitive motions, talk with your doctor about ways to protect your joints.

Can I reverse arthritis if I lose weight?

Weight loss cannot repair cartilage that has already worn away, but it can significantly reduce pain and slow further damage in osteoarthritis, especially in weight-bearing joints. It may also help reduce inflammation in rheumatoid arthritis. Even modest weight loss often brings noticeable improvement in symptoms.