Osteoarthritis vs Rheumatoid Arthritis — Understanding the Differences

Clinically reviewed by Louis Maxwell, First Contact Practitioner, HCPC PH128483. Last updated: June 2026.

Quick answer: Osteoarthritis (OA) and rheumatoid arthritis (RA) both cause joint pain but differ fundamentally. OA involves cartilage breakdown, usually from wear and tear, and commonly affects knees, hips, and hands. RA is an autoimmune disease where the immune system attacks joint linings, causing inflammation and damage — typically symmetrical, often starting in smaller joints on both sides of the body.

"Arthritis" is an umbrella term. It covers more than 100 different conditions affecting the joints — but two types dominate the conversation: osteoarthritis (OA) and rheumatoid arthritis (RA). They share a name. They both cause joint pain. But they are very different diseases with different causes, different treatments, and different outcomes. Understanding which one you have matters enormously — because the right treatment depends on it.

What Is Osteoarthritis (OA)?

Osteoarthritis is the most common type of arthritis in the UK: around 8.75 million people aged 45 and over have sought treatment for it (Arthritis Research UK, now Arthritis UK, 2013; cited by NICE CKS). It is sometimes called "wear-and-tear" arthritis, though that phrase oversimplifies things. The smooth cartilage that cushions the ends of your bones gradually breaks down. Over time, the joint space narrows, bone rubs on bone, and the joint itself may change shape. Small bony growths called osteophytes (bone spurs) may form. Commonly affected joints include knees, hips, hands (especially the ends of the fingers and base of the thumb), and the spine. OA becomes more common with age — most people are over 45 at diagnosis. Being overweight, having a previous joint injury, or a family history of OA all increase the risk. Pain typically worsens with activity and improves with rest. Morning stiffness usually lasts less than 30 minutes.

What Is Rheumatoid Arthritis (RA)?

Rheumatoid arthritis is an autoimmune disease. The body's immune system — which normally fights infection — mistakenly attacks the lining of the joints (the synovium). This causes inflammation, swelling, and eventually joint damage. RA affects around 430,000 people in the UK. It is less common than OA but generally more aggressive. The synovium becomes inflamed and thickened. Over time, this inflammation can erode cartilage and bone, leading to joint deformity. RA can also affect other parts of the body — the heart, lungs, eyes, and blood vessels. RA usually affects both sides of the body symmetrically — both hands, both wrists, both feet. Small joints are often affected first. It can start at any age, but most commonly begins between 40 and 60. Women are two to three times more likely to develop RA than men. Smoking is a major risk factor. Morning stiffness in RA often lasts more than an hour. Joints may feel hot, swollen, and tender. Fatigue and a general feeling of being unwell are common.

Key Differences at a Glance

• What is it? OA is wear-and-repair breakdown of cartilage. RA is an autoimmune disease — the immune system attacks joints.
• Who gets it? OA: more common with age (45+), linked to wear, injury, and weight. RA: can start at any age, women affected more, linked to genetics and smoking.
• Joints affected: OA often one-sided — knees, hips, hands, spine. RA usually symmetrical (both sides) — hands, wrists, feet first.
• Morning stiffness: OA — less than 30 minutes. RA — more than 1 hour.
• Swelling: OA — bony, firm. RA — soft, warm, spongy.
• Systemic symptoms: OA — rare. RA — common (fatigue, fever, weight loss, inflammation in other organs).
• Blood tests: OA — normal inflammatory markers. RA — raised CRP/ESR; positive rheumatoid factor or anti-CCP antibodies in many cases.
• Treatment focus: OA — exercise, weight management, pain relief, surgery if needed. RA — DMARDs, biologics, steroids to control the immune system.

Treatment Differences

OA treatment aims to manage symptoms and maintain function. NICE guidelines recommend a stepped approach: exercise and weight management first, then pain relief (paracetamol, NSAIDs), physiotherapy, joint injections (corticosteroids), and surgery (joint replacement). There are currently no drugs that slow OA progression. RA treatment aims to stop the immune system from attacking the joints and prevent permanent damage. Early, aggressive treatment is critical. The approach includes DMARDs (methotrexate usually first), corticosteroids short-term to settle inflammation, biologics if DMARDs are not enough, and physiotherapy and occupational therapy. The "treat-to-target" approach — aiming for remission — is the standard of care in the NHS.

Can You Have Both OA and RA?

Yes, it is possible to have both. In fact, this is not uncommon. Someone with long-standing RA may develop secondary OA in the affected joints because of the damage caused by inflammation over time. Diagnosis and treatment of dual conditions require careful management by your rheumatology team.

Getting the Right Diagnosis

If you have joint pain, the most important first step is getting the right diagnosis. Expect a GP assessment (questions about symptoms), a physical examination (feeling joints for swelling, warmth, range of motion), blood tests (inflammatory markers, rheumatoid factor, anti-CCP antibodies), imaging (X-rays showing cartilage loss in OA or joint erosion in RA, ultrasound or MRI for more detail), and referral to a rheumatologist if RA or another inflammatory arthritis is suspected. Early treatment makes a huge difference.