Swollen joints

You may also have stiffness, redness, heat and a decreased range of movement.

Joint swelling can make it difficult to perform ordinary tasks at work or at home, such as using a computer mouse and climbing stairs. Chronic (long-term) swelling and discomfort can affect your work, social or family life.

There are things you can try to reduce the swelling on your own. However, you should see your doctor if you think your joint may be infected, or if swelling hasn’t gone down after a few days.

Swollen joints can happen when there’s more fluid than normal in the tissues around your joints. This is due to inflammation in these tissues, which is part of your body’s natural immune response to tissue damage or infection.

If one joint is swollen, it's usually due to a joint injury, such as a sprain, dislocation or fracture. This is usually accompanied by pain.

Causes of pain and swelling in one joint

• Baker’s cyst — a build-up of fluid at the back of your knee
• Bursitis — swelling and tenderness usually in one joint caused by inflammation of the jelly-like sac that cushions your joints (bursa)
• Bleeding into the knee joint — injury to the knee joint eg a torn ligament or knee fracture can cause bleeding into the joint spaces (haemarthrosis); this causes bruising, swelling, stiffness and warmth, and is more common if you are taking anticoagulants eg warfarin; you should go to A&E if you think you are bleeding into your joint
• Damaged knee joint — this can cause knee pain but knee pain is not always caused by a joint problem
• Damaged cartilage at the back of the kneecap
• Gout or pseudogout — types of arthritis caused by a build-up of mineral crystals in your joints, leading to repeated attacks of pain, redness, swelling and warmth; gout usually affects the joints of your big toes first while pseudogout usually affects the knee joints first; it is important to see your GP if you're concerned you have gout or pseudogout because if left untreated, your joints can become permanently damaged

Traumatic synovitis can also cause a joint to swell. This occurs when your joint lining becomes inflamed after an injury. You can manage your symptoms by applying ice packs, resting your joint and taking a non-steroidal anti-inflammatory (NSAID) eg ibuprofen.

Less common causes of swelling and pain in one joint include: 

• A broken bone or fracture eg a break or fracture of your ankle, arm, hip, leg or wrist
• Arthritis — this includes:
• Osteoarthritis — this can affect one or more joints
• Psoriatic arthritis — this affects one in five people with psoriasis and can affect one or more joints
• Reactive arthritis — this usually develops in young adults after an infection
• Rheumatoid arthritis — pain usually starts in one joint and comes and goes
• Osgood-Schlatter's disease — swelling and tenderness just below the kneecap

Causes of pain and swelling in multiple joints

If more than one joint is swollen, it may be caused by an underlying condition, such as arthritis. Common types of arthritis are:

• Gout — often causing swelling and pain in your big toe first before affecting other joints 
• Osteoarthritis — deterioration of the joints due to the cartilage around them wearing away, which causes the bones to rub against each other; over time pain, stiffness and swelling worsen; it can affect one or multiple joints
• Psoriatic arthritis — an autoimmune disorder (this is when your immune system attacks your own healthy tissues) that affects one in five people with psoriasis; it can affect one or multiple joints; flare-ups are unpredictable but treatable
• Rheumatoid arthritis — an autoimmune disorder causing inflammation that usually affects many joints, particularly in your feet, hands and wrists; in the early stages, pain comes and goes, and there can be long gaps between attacks

A hot, swollen joint that develops quickly could be due to septic arthritis — a bacterial infection in your joint. If you suspect you have septic arthritis, you should see your GP or visit A&E as soon as possible. In some cases, swollen joints can be caused by ulcerative colitis — a chronic condition that inflames the lining of the large intestine (colon or large bowel). 

Other conditions that can affect your joints include:

• A viral infection eg hepatitis or rubella — this causes joint pain and a fever
• Connective tissue diseases — this includes: 
• Lupus — an autoimmune disorder affecting many organs and areas of the body, including joints, kidneys and the skin 
• Scleroderma — an autoimmune disorder affecting connective tissue under the skin
• Tendonitis — swelling, pain and sometimes crepitus due to inflammation in a tendon

Less common causes of swelling and pain in multiple joints include:

• Certain medical treatments eg the antibiotic isoniazid, the high blood pressure medication hydralazine and steroid therapy
• Hypertrophic pulmonary osteoarthropathy — a rare condition affecting people with lung cancer, which also causes enlargement of the ends of the fingers (clubbing)
• Rare conditions causing inflammation of the blood vessels — this includes:
• Behçet's syndrome 
• Henoch-Schönlein purpura — this usually occurs in children
• Rare types of arthritis eg ankylosing spondylitis, juvenile arthritis or reactive arthritis
• Rheumatic fever — an inflammatory condition caused by untreated strep throat or scarlet fever
• Sarcoidosis — a rare condition that causes small patches of red, swollen tissue to develop in organs

In rare cases, certain cancers can also cause joints to become painful and swollen.

You should arrange to see your GP if:

• You have other symptoms, including fever (a sign of septic arthritis)
• Your joint looks disfigured
• Your swelling is very painful 
• Your swelling lasts for more than a few days or is getting worse
• Your swelling occurred after a serious injury
• Your swelling occurred without any apparent cause

Your GP will discuss your symptoms and examine your joint(s). They may ask you questions, such as: 

• Do you have any other symptoms? 
• Does anything make your swelling better or worse? 
• How severe has your swelling been?
• When did your joint swelling start?

They may also arrange for you to have blood tests and imaging tests, such as:

• An X-ray
• CT scan
• MRI scan
• Ultrasound scan

In some cases, your GP may refer you to an orthopaedic consultant for further investigations, such as:

• Arthroscopy (keyhole surgery) to examine your joint and repair it if necessary
• Joint aspiration to remove the fluid for examination

Treatments depend on the underlying reason for your joint inflammation.

If your joint swelling occurred after an injury, your doctor may recommend treatments you can do at home, such as: 

• Avoiding putting weight on or moving your affected joint
• Taking over-the-counter anti-inflammatory medication eg ibuprofen
• Using an ice pack for around 20 minutes at a time to reduce swelling

You should still stay active to prevent the muscles around your joint weakening and affecting your range of movement. 

Your doctor may prescribe anti-inflammatory medications or antibiotics if your swelling is caused by an infection. In some cases, they may offer a joint injection to reduce swelling and pain in the joint.

If your swelling is caused by an underlying chronic condition eg arthritis, gout or lupus they will recommend specific treatment for that condition.