Causes of Warm or Hot Joints

Traumatic, Infectious, and Rheumatic Causes

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The warmth of a joint can tell you many things. Generally speaking, if a joint is warm enough to catch your attention, it is something you shouldn't ignore. While joint warmth can occur if you are recovering from a joint injury—during which the body will respond with inflammation—it can also foreshadow a condition or disease that needs immediate attention.

Woman touching warm, red ankle. / DigitalVision / Getty Images


Joint warmth doesn't usually occur on its own and will often be accompanied by pain, stiffness, and swelling. These and other symptoms can provide clues as to what the cause may be, which will broadly be described as being either traumatic, infectious, or rheumatic.

Traumatic Causes

Joint trauma is a term used to describe an acute injury rather than one that develops over time. These typically occur as a result of sports, a fall, or a blunt-force impact. The trauma may affect the bone, muscles, tendons, ligaments, cartilage, and other structures within the joint.

Among some of the more common joint injuries:

  • Dislocation, also referred to as a luxation, occurs when the bones of a joint are either fully or partially separated.
  • Fracture is used to describe a broken bone.
  • Sprains occur when the ligaments that hold the joint bones together are damaged or partially torn by overstretching or twisting.
  • Strains occur when a muscle or tendon is damaged or partially torn ("pulled") by overstretching or an excessive contraction.

Some of these injuries can occur together. They most typically involve the ankle, knee, wrist, and shoulder. One of the most common is an anterior cruciate ligament (ACL) tear, which is frequently seen in athletes.

While the pain from a traumatic injury is usually immediate, it can sometimes feel like a minor knock, only to progressively worsen over hours or days. In addition to joint warmth, bruising, stiffness, swelling, and joint deformity are common.

Infectious Causes

Infections of the joint may be caused by a penetrating injury that introduces a pathogen, most often a bacterium, into the joint space, or be the consequence of a systemic (whole-body) infection in which the joint is "seeded" with bacteria from the bloodstream.

Situations where a warm or hot joint is caused by infection include:

  • Septic arthritis: is the infection of a joint by bacteria or fungus. Bacterial septic arthritis is most often the result of "seeding" from a bloodstream infection or contamination after joint surgery.
  • Lyme disease is a tick-borne illness caused by the bacterium Borrelia burgdorferi. Joint pain and inflammation are characteristic of the infection alongside a characteristic "bull's eye" rash and flu-like symptoms.
  • Cellulitis is a serious and potentially life-threatening bacterial infection of the skin. If cellulitis occurs over a joint, it may look and feel like arthritis.
  • Osteomyelitis is a bacterial infection of the bone. It often arises after a bacterial infection elsewhere in the body, such as a urinary tract infection or pneumonia, spreads to the bones. People with diabetes are especially vulnerable to osteomyelitis.
  • Reactive arthritis is a form of arthritis that develops in response to a bacterial infection elsewhere in the body, often days or weeks earlier.
  • Rheumatic fever is an uncommon illness associated with inadequately treated strep throat or scarlet fever. Multiple-joint inflammation is one of the telltale signs of rheumatic fever.

Joint warmth is usually one of the first symptoms of a joint infection alongside fever (mild to high-grade) and malaise. Other symptoms include joint pain, redness, swelling, and stiffness. A penetrating wound may also develop an abnormal discharge.

Seek emergency care if the joint pain is accompanied by a fever of over 100.4 F, shaking chills, or noticeable red streaks on the skin leading away from the infected area (a sign of cellulitis).

Rheumatic Causes

Rheumatism is a term that broadly describes any disease that causes chronic or intermittent pain and inflammation in the joints, muscles, or connective tissues. Some of these conditions are associated with age or repetitive use, while others are caused by an autoimmune disease in which the immune system attacks its own cells and tissues.

Among the conditions associated with accumulative joint damage:

  • Bursitis is the inflammation of the cushioning sac (bursa) around a joint space, most often as the result of repetitive motion. Commonly affected areas include the knees, shoulders, elbows, and hips.
  • Osteoarthritis is the classic "wear-and-tear" arthritis in which joint cartilage is gradually worn down over time, causing joint stiffness, deformity, and restriction of motion.
  • Tendinitis is the inflammation of tendons, a condition typically associated with repetitive use. Some types are popularly referred to as tennis elbow, swimmer's shoulder, and jumper's knee.

Among the conditions caused by an autoimmune or inflammatory disease:

  • Gout is caused by the progressive deposit of uric acid crystals in the joint space, most predominately the big toe.
  • Polymyalgia rheumatica is an inflammatory disorder most affecting people over 65 that causes pain and stiffness, especially in the shoulders.
  • Psoriatic arthritis is a form of arthritis that frequently develops in people with psoriasis.
  • Rheumatoid arthritis is the most common form of autoimmune arthritis in which arthritic pain is most often bilateral (affecting the same joints on both sides of the body).
  • Juvenile idiopathic arthritis is the most common form of arthritis in children and adolescents.

A key characteristic of rheumatic diseases is the recurrence of symptom flares, also known as exacerbations. Joint warmth is often one of the precipitating signs of exacerbation as the immune system suddenly turns its defenses on itself.

When to See a Doctor

A warm joint on its own may mean nothing or be a sign of a worrying condition. Though you may be able to go about your day ignoring it, it's best not to. If the symptoms persist or worsen, speak with your doctor. If needed, you may be referred to a specialist known as a rheumatologist for further investigation.

If a joint is suddenly and excessively hot, don't wait a day or two to have it looked at. Go the nearest walk-in clinic, urgent care center, or emergency room if your doctor is unable to see you, especially if the joint is painful, swollen, or visibly deformed.

If the pain is extreme and accompanied by fever, chills, dizziness, irregular heartbeat, and rapid changes in the skin's color or appearance, seek emergency care irrespective of whether you have had a recent injury or surgical procedure. Symptoms like these rarely resolve on their own and may lead to a medical crisis if left untreated.


Since joint warmth rarely occurs on its own, the doctor will start by looking at any other symptoms you have in conjunction with a review of your medical history, family history, current drug treatments, or any injury, infection, or medical procedure you may have recently had.

These can usually point the doctor in the general direction of the possible causes and help determine which tests are most appropriate. Among them:

  • A physical exam would be performed to see if there is any joint pain, rash, swelling, fever, or restriction in movement.
  • Blood tests like an erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) can detect generalized inflammation. Other blood tests can check for high levels of uric acid consistent with gout or the presence of rheumatoid factor (RF) consistent with rheumatoid arthritis.
  • Imaging tests like an ultrasound, X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) can check for bone or soft tissue damage, including dislocation, hemorrhage, or effusion (accumulation of fluids).
  • Joint aspiration (arthrocentesis) involves the removal of fluid from the joint space for evaluation in the lab. Arthrocentesis is generally indicated if the symptoms are severe and an infection is suspected, especially in people with preexisting arthritis.
  • Blood and tissue cultures may help isolate the bacterial or fungal cause of an infection.
  • Antinuclear antibody (ANA) tests detect specific proteins, known as autoantibodies, which are associated with the autoimmune attack.

Differentiating the possible causes may take time, but there are clues that can often help. These include how many joints are affected, whether the joint pain in bilateral or unilateral (differentiating rheumatoid arthritis from osteoarthritis), whether the event is recurrent or isolated, or whether the symptoms are limited to the joint or more constitutional (systemic).


The treatment of a joint condition is ultimately directed by the diagnosed cause. The options can be broadly described based on whether the cause is traumatic, infectious, or rheumatic.

Joint Injuries

Mild joint injuries may only require rest, restriction of movement, ice application, and non-steroidal anti-inflammatory drugs (NSAIDs). More serious ones may require complete joint immobilization. Surgery may be indicated if a bone is fractured or there are ruptured tendons or ligaments that cannot heal on their own.

Joint Infections

Bacterial joint infections are usually treated with a combination of intravenous antibiotics and the "washing out" of the joint, either with surgery or repeated extractions of joint fluid (arthrocentesis). Bacterial cultures of the joint fluid and/or blood can help decide which antibiotic is best.

Fungal infections, more commonly seen in people with compromised immune systems, are treated with antifungals, either oral or intravenous.

Rheumatic Disorders

Repetitive motion injuries are treated in much the same way as a traumatic injury. Osteoarthritis benefits most from the considered use of pain medications along with physical therapy, exercise, weight loss, and ice or heat application.

Oral or injected corticosteroids, intra-articular hyaluronic injections, arthroscopic surgery, and joint replacement may be considered if the disease progresses.

Rheumatoid arthritis and other autoimmune joint disorders may be treated in a similar manner but may also be brought under control with disease-modifying antirheumatic drugs (DMARDs) and other biologic and targeted treatments that suppress specific parts of the immune response.

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