A joint that suddenly becomes red, hot, swollen and intensely painful may look like gout—but several other conditions can look very similar. Some are relatively routine. One of the most important, septic arthritis, is a joint infection that can become serious quickly.
This guide is not a self-diagnosis checklist. Its purpose is to help you understand why a medical provider may ask certain questions, order certain tests or recommend joint aspiration instead of assuming every painful swollen joint is gout.
If this is your first severe unexplained attack, if you have fever or feel seriously unwell, or if your symptoms are unusual for you, contact a healthcare professional promptly.
Why gout can be difficult to identify from symptoms alone
Gout often has a recognizable pattern: rapid onset—sometimes overnight—of severe pain, swelling, warmth and tenderness. The big toe is classic, but gout can also affect the foot, ankle, knee, fingers, hand, wrist and elbow. The NICE guideline specifically tells clinicians to consider gout in these other joints while also assessing for septic arthritis, calcium pyrophosphate deposition (CPPD) and inflammatory arthritis.
The problem is that redness, warmth, swelling and pain are signs of inflammation, not a unique fingerprint for gout. The diagnosis depends on the full pattern and, when necessary, testing.
Gout vs. septic arthritis: the distinction that matters most
Septic arthritis is an infection inside a joint and can be a medical emergency. It may cause severe pain, swelling, warmth, reduced movement and sometimes fever. Unfortunately, gout can produce many of the same findings.
NICE recommends immediate referral when septic arthritis is suspected. The NIH/NCBI review of gout also emphasizes that inflammatory blood markers are not specific enough to reliably separate acute gout from infection.
A clinician may need to remove fluid from the affected joint and send it for crystal analysis and, when infection is a concern, microbiologic testing. Importantly, gout and infection can occasionally occur together, so finding crystals does not always end the evaluation if the clinical picture still raises concern for infection.
Read our focused guide: Gout vs. Joint Infection: When a Red, Hot Joint Is an Emergency.
Gout vs. pseudogout (CPPD)
CPPD, often called pseudogout, is another crystal arthritis. Instead of monosodium urate crystals, CPPD involves calcium pyrophosphate crystals. It can cause an abrupt, painful, warm and swollen joint that looks remarkably similar to gout.
Pseudogout commonly affects the knee and wrist, although other joints can be involved. The Mayo Clinic describes sudden intense joint pain and swelling as reasons to seek medical care. Crystal analysis of joint fluid can help distinguish CPPD from gout when the diagnosis is uncertain.
See Gout vs. Pseudogout: Symptoms, Crystals and Testing.
Gout vs. cellulitis
Cellulitis is an infection of the skin and underlying soft tissues. It can cause redness, warmth, swelling and tenderness around a foot, ankle, hand or other area—sometimes close enough to a joint that it is difficult to tell where the inflammation is coming from.
Spreading redness, systemic illness or concern for infection should prompt medical evaluation. Because appearances overlap, photographs and internet symptom lists are not a reliable way to decide whether redness is “just gout.”
Gout vs. an injury, sprain or stress fracture
“I didn’t injure it” is useful information, but it does not completely eliminate mechanical causes. A stress fracture can develop from repeated loading without one dramatic accident. Minor sprains, tendon injuries and joint irritation can also become painful after an activity you did not consider an injury at the time.
Clinicians look at the location and pattern of tenderness, whether pain is tied mainly to movement or weight-bearing, whether there was a recent increase in activity, and whether imaging is needed. Gout can hurt both with movement and at rest, but symptom overlap means the history and examination matter.
Gout vs. bunion or hallux rigidus
The base of the big toe is also where bunions and osteoarthritis of the first toe joint can cause pain. A bunion is a structural change that usually develops over time. Hallux rigidus is arthritis that causes stiffness and pain in the big-toe joint, particularly when bending the toe.
Gout is more famous for an abrupt inflammatory attack, but people can have more than one foot problem at the same time. A clinician or podiatry/orthopedic professional may use examination and imaging to sort out chronic structural problems from an acute crystal flare.
Gout vs. rheumatoid, psoriatic or other inflammatory arthritis
Other inflammatory arthritides can produce swollen painful joints. Rheumatoid arthritis more often develops as a persistent inflammatory condition involving multiple joints, frequently in a symmetric pattern. Psoriatic arthritis can be asymmetric and may occur with psoriasis, nail changes or swelling of an entire finger or toe. Reactive arthritis can follow certain infections.
These are patterns, not rules. Gout can become chronic and affect multiple joints, while other forms of arthritis can sometimes present in less typical ways. See Gout vs. Rheumatoid Arthritis and Other Arthritis for more detail.
Gout vs. bursitis or tendon problems
Bursitis and tendinopathy can cause localized swelling, tenderness and pain around joints—such as the ankle, heel, elbow or knee—without the inflammation originating inside the joint itself. Gout can also involve structures around a joint, so the distinction may require a hands-on examination and sometimes imaging or aspiration.
Can location tell you whether it is gout?
Location can raise or lower suspicion, but it cannot make the diagnosis. The big-toe joint is strongly associated with gout, but the Mayo Clinic notes that gout can also affect ankles, knees, elbows, wrists and fingers. NICE includes the midfoot, ankle, knee, hand, wrist and elbow in its diagnostic guidance.
Our Gout Beyond the Big Toe guide covers those locations in more depth.
What tests help tell gout from something else?
A medical provider may use several pieces of information rather than relying on one test:
- History and examination: how fast symptoms began, which joint is involved, previous attacks, warmth, swelling, range of motion and other health factors.
- Serum uric acid: useful in context, but high uric acid alone does not prove gout and a normal level during a flare does not automatically exclude it.
- Joint-fluid analysis: can identify urate crystals, CPPD crystals and help evaluate infection.
- Imaging: X-ray, ultrasound or dual-energy CT may be useful in selected cases, especially when the diagnosis remains uncertain.
- Other blood tests: may help evaluate inflammation, infection or another type of arthritis, but inflammatory markers by themselves do not distinguish gout from septic arthritis.
See our complete guide to How Gout Is Diagnosed. If your uric acid result was normal during an attack, see Can You Have Gout With Normal Uric Acid?.
When to contact your medical provider
Contact a medical provider for a new episode of severe unexplained joint pain, particularly when the joint is swollen, warm or red/discolored. It is especially important to get prompt care if you have fever, feel seriously unwell, cannot use the joint, or there is concern for infection.
If the pattern keeps returning, that is also worth evaluating even if attacks eventually disappear on their own. Recurrent flares can provide important diagnostic clues and, if the cause is gout, effective long-term treatment can reduce future attacks and crystal burden.
For help preparing, use our gout appointment guide. Bring your medication list, recent laboratory results, timing of attacks and—if you have them—photos of visible swelling or redness from earlier in the flare.
Questions worth asking
- What diagnoses are you considering besides gout?
- Is there any reason to be concerned about a joint infection?
- Would joint aspiration help distinguish gout, CPPD and infection?
- If my uric acid was normal during the attack, should it be repeated later?
- Would imaging add useful information in my case?
- Should I see a rheumatologist if the diagnosis remains uncertain?
The bottom line
Gout has a recognizable pattern, but no symptom checklist can safely tell every red, hot, painful joint apart. The most useful role for this information is to help you recognize when gout is possible, understand why your medical provider may consider other causes, and ask better questions during the evaluation.
When infection is a possibility, do not wait for an online article to settle the question. Get medical care.