Septic arthritis usually causes sudden pain in one joint, along with swelling, warmth, and difficulty moving it. The skin nearby may look red or feel hot, and fever or chills can occur. The knee is often affected, but other joints can be involved. Fever is not always present, and babies or young children may show irritability or reluctance to move a limb.
What are the main symptoms of septic arthritis?
Septic arthritis is an infection inside a joint. Symptoms often develop over hours or a few days, although the pattern can differ depending on the person and the infection. The joint may become painful, swollen, warm, and difficult to move as inflammation develops.
According to the NHS, the main symptoms include sudden joint pain, swelling, changes in the skin over the joint, restricted movement, and sometimes fever. These symptoms need urgent medical assessment because an untreated joint infection can damage the joint.
- Sudden joint pain: Pain may begin quickly and become pronounced over a short period. Moving the joint or putting weight on it may become difficult.
- Swelling: The affected joint may look larger than usual because fluid and inflammation develop around the joint tissues.
- Warmth: The skin over the joint may feel warmer than nearby skin.
- Redness or skin color changes: The skin around the affected area may look red or appear to have a different color. Redness can be less noticeable on darker skin.
- Reduced movement: Bending, straightening, or otherwise moving the joint may cause pain or become difficult.
- Tenderness: The joint may be painful when touched or during ordinary movement.
- Fever or chills: Some people develop a raised temperature, chills, or a general feeling of being unwell. Others do not have an obvious fever.
Which joints are usually affected?
Septic arthritis can affect any joint, but it commonly involves a large joint such as the knee or hip. The ankle and shoulder can also be affected. In many cases, only one joint develops symptoms at a time, although infections involving multiple joints can occur.
The Cleveland Clinic notes that pain, tenderness, swelling, warmth, fever, and limited joint movement are common features. The exact location of the symptoms depends on which joint is affected. For example, an infected knee may make walking difficult, while an affected shoulder may interfere with reaching or lifting the arm.
Symptoms may be especially noticeable during movement or when trying to use the affected joint normally. A person might avoid bending a knee, putting weight on a leg, or moving an arm because doing so causes pain.
How quickly do septic arthritis symptoms appear?
Acute septic arthritis often develops rapidly, with symptoms emerging over hours or days rather than gradually over many months. Pain and swelling may increase quickly, and normal movement can become difficult within a short period.
According to Mayo Clinic, septic arthritis often causes pain that comes on quickly and makes it difficult to use the affected joint. The joint may also become swollen and warm, and the skin over the area may change color. New, rapidly developing joint pain is particularly important to take seriously when it occurs with swelling or restricted movement.
Not every joint infection follows exactly the same timeline. Some infections, including those involving an artificial joint, may present differently. New pain or swelling in a joint replacement deserves prompt medical attention, even when the surgery took place months or years earlier.
Can septic arthritis cause fever or other symptoms throughout the body?
Yes. Fever and chills can accompany joint symptoms, and a person may feel generally unwell. However, fever is not required for septic arthritis to occur. Its absence does not reliably exclude a joint infection, particularly in people whose immune response may be reduced.
The Merck Manual Professional Edition explains that many, but not all, people with acute infectious arthritis have a fever. In some cases, signs of inflammation or general illness may be less obvious. This is one reason a new, painful, swollen joint should not be dismissed simply because a person has no fever.
When an infection spreads beyond the joint and affects the body more widely, additional signs of serious illness may develop. These can include marked weakness, confusion, rapid breathing, or feeling extremely unwell. Such symptoms warrant emergency medical care.
What do septic arthritis symptoms look like in babies and children?
Septic arthritis can occur in infants and children as well as adults. Young children may be unable to explain where they hurt, so changes in their behavior or movement can be important. A child might stop using an arm, refuse to stand or walk, or become unusually upset when the affected area is moved.
According to MedlinePlus, symptoms in children can include joint pain, swelling, redness, fever, and an inability or reluctance to move the affected limb. Infants may instead show irritability, fussiness, changes in feeding, or reduced spontaneous movement. Fever may be present, but it can also be absent.
- Refusing to walk, crawl, stand, or use a limb as usual.
- Crying or becoming distressed when a joint is touched or moved.
- Swelling or warmth around a joint.
- Fever or an unusual change in general behavior.
- In babies, feeding less than usual or appearing unusually irritable.
These changes are not specific to septic arthritis, but a child with new joint swelling, significant pain, or an unexplained refusal to move a limb needs urgent medical assessment. Infants and young children may have difficulty describing their symptoms clearly.
When should symptoms be assessed urgently?
Seek urgent medical care if sudden joint pain occurs with swelling, warmth, skin color changes, or difficulty moving the joint. Do not wait for a fever to develop before seeking help. If the pain is intense, symptoms are progressing quickly, or the person feels very unwell, assessment in an emergency department is appropriate.
Prompt assessment is also important when new joint symptoms develop after joint surgery, in a person with an artificial joint, or in someone with a weakened immune system. These circumstances can affect how an infection presents, and some people may have fewer obvious signs than expected.
Septic arthritis can resemble other joint problems, including crystal-related arthritis and some inflammatory conditions. Symptoms alone cannot reliably distinguish these causes. A healthcare professional considers how quickly symptoms began, the affected joint, medical history, examination findings, and appropriate tests to determine what is happening.
Why are early symptoms important?
An infection inside a joint can damage cartilage and other joint structures if treatment is delayed. Recognizing new pain, swelling, warmth, and reduced movement as reasons for urgent assessment can help prevent complications. The key is not to wait for every typical symptom to appear or assume that a lack of fever rules out infection.
If septic arthritis is suspected, healthcare professionals may examine the joint and test a sample of joint fluid to look for infection. Blood tests and other investigations may also be needed. The purpose of these assessments is to identify the cause of the symptoms and guide timely treatment.