SymptomBones, joints & muscles
Joint Warmth: What a Hot Joint Means
Joint warmth means a joint feels noticeably warmer than the same joint on the other side or the skin around it. Warmth is a sign of inflammation: increased blood flow to an irritated joint lining. The usual causes are gout, a joint injury, rheumatoid or psoriatic arthritis, and bursitis. A single hot, swollen, painful joint with fever may be a joint infection (septic arthritis), which can destroy the joint within days and needs same-day care.
Also called: Warm joint, hot joint, heat over a joint, inflamed joint
At a glance
- What it means
- Inflammation in or around the joint, with increased blood flow.
- Most common causes
- Gout, pseudogout, injury, inflammatory arthritis and bursitis.
- Most dangerous cause
- Septic arthritis, a bacterial infection inside the joint.
- Key test
- Drawing fluid from the joint (joint aspiration) to look for crystals and bacteria.
- What to do
- Same-day care for one hot, swollen joint with fever or inability to move it.
When to get help
Call 911 or go to the ER
- A hot, swollen, very painful joint with fever above 38 °C (100.4 °F), chills or feeling very unwell (possible septic arthritis)
- A hot joint that you cannot move or put weight on, especially with an artificial joint, recent joint injection or IV drug use
- Spreading redness up the limb with fever and confusion
See a doctor within a day or two
- A single hot, swollen joint without fever that came on over hours or days, even if you have had gout before and it feels different
- A warm, swollen knee after an injury with rapid swelling within 2 hours (possible bleeding in the joint)
- A hot, swollen calf or leg (possible blood clot) rather than a joint
- A warm joint in a child who refuses to walk or use the limb
Book a routine appointment
- Several warm, swollen joints with morning stiffness lasting more than 30 minutes
- Warm, swollen joints after a recent bout of diarrhea, a sexually transmitted infection or a tick bite
- A warm joint that keeps flaring and settling
Usually safe to manage at home
- Mild warmth after overuse or a minor sprain that is improving with rest, ice and elevation
- A known gout flare that matches your previous attacks, while you follow your treatment plan
Why a joint gets warm
When the lining of a joint (the synovium) or the tissues around it become inflamed, blood vessels widen and fluid leaks into the area. The four classic signs of inflammation follow: warmth, redness, swelling and pain. You can check warmth by placing the back of your hand on the joint and comparing it with the other side.
Warmth tells you there is active inflammation, which helps separate inflammatory problems from wear-and-tear osteoarthritis, which usually causes little warmth.
Causes of a warm joint
One hot joint
| Cause | Clues |
|---|---|
| Septic arthritis | Rapidly worsening pain, swelling, warmth; fever; cannot move the joint; knee most common. Risk higher with diabetes, rheumatoid arthritis, joint replacements, injections and IV drug use |
| Gout | Sudden, intense pain, often overnight; big toe, ankle, foot or knee; very red and shiny skin; peaks within 24 hours |
| Pseudogout | Similar to gout but usually in the knee or wrist of older adults; calcium crystals |
| Injury | Sprain, ligament tear or fracture; bleeding in the joint causes fast swelling |
| Bursitis | Warm, squishy swelling over the elbow or kneecap, often from leaning or kneeling; can become infected |
| Lyme disease | Swollen, warm knee weeks to months after a tick bite, often less painful than it looks |
| Reactive arthritis | Knee, ankle or toe after a gut or sexually transmitted infection; sometimes red eyes or urinary symptoms |
Several warm joints
- Rheumatoid arthritis: warm, swollen small joints of the hands and feet on both sides, with prolonged morning stiffness.
- Psoriatic arthritis: warm joints, sausage-like swollen fingers or toes, and psoriasis.
- Viral arthritis: after parvovirus, hepatitis or other infections, usually settling within weeks.
- Lupus and other autoimmune diseases.
- Gonococcal arthritis: joint pain moving from joint to joint, a few skin spots, and tendon inflammation in sexually active young adults.
Around the joint, not in it
- Cellulitis: spreading red, hot skin infection over a joint; the joint itself usually moves freely.
- Tendinitis: warmth along a tendon with pain on using that muscle.
- Blood clot (DVT): a warm, swollen calf can be mistaken for a knee or ankle problem.
How doctors find the cause
A doctor will ask how quickly it started, about injury, previous attacks, fever, medicines (diuretics raise gout risk), sexual history, tick bites and other illness. They will check whether the joint itself is inflamed or just the skin and tissues around it, and examine other joints.
The most important test for a single hot joint is joint aspiration: a needle draws fluid from the joint. The fluid is examined for:
- white cell count (very high in infection)
- crystals (needle-shaped urate in gout, rhomboid calcium pyrophosphate in pseudogout)
- bacteria on Gram stain and culture
Other tests include blood count, CRP and ESR, uric acid, blood cultures, X-rays and ultrasound. Gout and infection can occur together, so finding crystals does not rule out infection.
Treatment
- Septic arthritis: IV antibiotics and drainage of the joint by needle or surgery, usually in the hospital.
- Gout and pseudogout: NSAIDs, colchicine or steroids for the flare; for gout, long-term urate-lowering treatment if attacks recur.
- Inflammatory arthritis: disease-modifying medicines from a rheumatologist, started early to prevent joint damage.
- Injury: rest, ice, compression and elevation; imaging if severe.
- Bursitis: rest, padding and NSAIDs; aspiration and antibiotics if infected.
Home care while you wait to be seen
- Rest the joint and raise it above heart level.
- Apply a cold pack wrapped in a cloth for 15 to 20 minutes at a time.
- Take acetaminophen (paracetamol) or an NSAID such as ibuprofen if suitable, following the label dose. Avoid NSAIDs if you have kidney disease, stomach ulcers or take blood thinners.
- Do not apply heat to an already hot joint.
Frequently asked questions
What does it mean when a joint is warm to the touch?
A warm joint is inflamed. The most common causes are gout, injury, inflammatory arthritis and bursitis. A joint infection is less common but serious. If one joint is hot, swollen and very painful, especially with fever, get seen the same day.
Why is my knee warm and swollen?
A warm, swollen knee can be from an injury, gout or pseudogout, a joint infection, rheumatoid or reactive arthritis, Lyme disease, or prepatellar bursitis from kneeling. If it came on quickly with fever, or you cannot bend or bear weight on it, seek urgent care.
Can osteoarthritis cause a warm joint?
Osteoarthritis usually causes only mild warmth, if any. A flare of osteoarthritis can make a knee slightly warm and swollen, but a clearly hot joint suggests gout, pseudogout, infection or inflammatory arthritis, which need different treatment.
Should I put ice or heat on a warm joint?
Use ice, not heat, on a warm, inflamed joint. Wrap a cold pack in a cloth and apply for 15 to 20 minutes at a time. Heat is better for stiff joints without warmth or swelling, such as osteoarthritis in the morning.
Sources
This guide was written from current patient and clinical guidance, including:
- American College of Rheumatology: Gout; Septic arthritis patient fact sheets
- American Academy of Family Physicians: Septic Arthritis in Adults; Diagnosing Acute Monoarthritis in Adults (American Family Physician)
- NHS: Septic arthritis
- Arthritis Foundation: Gout
- MedlinePlus: Joint swelling