Overview
Septic arthritis happens when germs reach a joint through the blood, or from an injury, surgery, or a shot. The knee and hip are most often affected.
The infection can damage the joint quickly. Recovery is good with fast antibiotics, but delay can cause permanent joint damage.
Symptoms
Symptoms usually come on quickly, over hours to a day or two.
- Red, hot, swollen joint
- Severe joint pain that's worse with movement
- Fever
- Not able to move the arm or leg with the infected joint
Less common
- Chills
- Knee pain and swelling
- Hand, finger, or wrist pain and swelling
- A rash and joint pain with gonorrhea
How it usually goes
- Hours to 1 to 2 days: Pain, swelling, and fever build quickly.
- Treatment: Antibiotics start right away; fluid is drained.
- Weeks: Antibiotics continue; the joint slowly heals.
Look up a symptom: Fever
When to get medical care
Causes
Most cases are caused by staph or strep bacteria that spread through the blood or enter during an injury or surgery. In young children, group B strep and Haemophilus influenzae can cause it. Gonorrhea can also infect joints.
Does it spread or run in families?
- Yes, it can spread from person to person.
- How it spreads: touch.
- Don't share towels, hats, combs, or bedding while it's being treated.
Who is more likely to get it
- Existing joint problems, like rheumatoid arthritis or gout
- A joint replacement
- Recent joint surgery or shots
- Diabetes or a weak immune system
- Very young or older age
Possible complications
- Sepsis: Infection spreading in the blood
- Bone infection: Infection spreading to the bone
Diagnosis
A healthcare professional needs to test fluid from the joint.
Questions you may be asked
- When the pain and swelling started
- Fever or chills
- Recent injury, surgery, or joint shot
- Arthritis, diabetes, or a weak immune system
The exam
They'll check the joint for heat, swelling, and how much it hurts to move.
Tests
Tests include:
- Joint fluid test: A needle removes fluid to look for germs and crystals (to rule out gout).
- Blood tests: Including blood cultures.
- X-ray or ultrasound: To look at the joint.
Treatment
Septic arthritis needs antibiotics, often through a vein at first, and draining the infected fluid.
Self-care
- Go to the emergency room or urgent care right away
- Rest and raise the joint while waiting for care
- Use cool compresses for comfort
- Exercise the joint once it starts to heal, as directed
Medicines
Treatment is given by your care team.
| Medicine | Helps with | Good to know |
|---|---|---|
| Antibiotics | Kills the infection | Take the full course, often several weeks. |
| Pain relievers Acetaminophen | Pain | Don't let pain relief delay getting care. |
Antifungal medicine is used if a fungus is the cause.
Fluid may be drained with a needle more than once. Severe cases need surgery to wash out the joint. Antibiotics are often continued for weeks.
How it compares
| Joint infection | Gout | Pseudogout | Bursitis | |
|---|---|---|---|---|
| Starts | Over hours to days | Suddenly, often at night | Suddenly | Gradually |
| Fever | Often | Sometimes | Sometimes | Rarely |
| Joint fluid | Germs | Uric acid crystals | Calcium crystals | Normal joint |
| Urgency | Same day | See a doctor soon | See a doctor | See a doctor |
Prevention
You can lower the risk:
- Treat skin and other infections early
- Keep wounds near joints clean
- Get vaccines, including Hib for children
- Treat STIs like gonorrhea
Which doctor treats this
- Start with your primary care provider (family doctor or internist).
- They may send you to an orthopedist (bone and joint doctor).
- A physical therapist can help with exercises to rebuild strength and motion.
Living with it
- Stay active with walking, swimming, or biking.
- Keep a healthy weight to ease joint strain.
- Long-term illness can affect mood. Tell your doctor if you feel down or anxious.
Support groups and helplines
- Arthritis Foundation: Helpline, exercise programs, and online community.
Back to school, work, or sports
- Stay home until you've had no fever for 24 hours without fever medicine and you're feeling better.
- For the next 5 days, wash hands often and wear a mask around others.
Children, pregnancy, and older adults
- Babies and young children: Most often under age 3, often in the hip. Watch for fever, fussiness, or crying when a leg is moved.
- Joint replacements: New pain, swelling, or fever in a replaced joint needs care right away.
- Older adults: May have less fever. Any new hot, swollen joint should be checked.
Pregnancy and breastfeeding
- If you're pregnant or planning to be, tell your prenatal provider about this condition.
- Some infections can pass to the baby during pregnancy or birth. Tell your provider if you've been exposed.
- Don't start or stop any medicine on your own. Some are safe in pregnancy and some need to be changed.
- Ask before taking any pain reliever. The FDA advises avoiding ibuprofen and naproxen after 20 weeks unless your doctor says to.
- Breastfeeding: Most medicines are fine, but ask. The NIH LactMed database lists what's known about each one.
Outlook
Recovery is good with fast antibiotic treatment. If treatment is delayed, the joint can be permanently damaged.
Getting ready for your visit
This is usually an urgent visit.
What to bring
- When symptoms started
- Recent injuries, surgery, or joint shots
- A list of medicines and health problems
Questions to ask
- Is this an infection or gout?
- Do I need surgery?
- How long will I need antibiotics?
- Will my joint recover?
Research studies
Research studies test new ways to find and treat health problems. Some are looking for volunteers. Talk with your doctor before joining one.
Search ClinicalTrials.gov for studies on Joint infection (septic arthritis)
Sources
Last updated 2026-11-12.