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- A hot, swollen, very painful joint can look like pseudogout but may be an infection. Go to A&E or call 999 if you also have a fever, shivers or feel very unwell, or if you have a joint replacement in the affected joint.
- Get a same-day GP appointment or call NHS 111 for any new hot, swollen joint, even without fever.
Quick answer: Pseudogout is sudden joint inflammation caused by calcium pyrophosphate (CPP) crystals. It is now usually called acute CPP crystal arthritis and is part of CPPD (calcium pyrophosphate deposition). It most often affects the knee or wrist in older adults. It is diagnosed by finding crystals in joint fluid, and flares are treated with rest, ice, anti-inflammatory medicines, colchicine or steroids. A hot joint with fever needs urgent checking for infection.
What is CPPD?
CPPD stands for calcium pyrophosphate deposition. Tiny crystals of calcium pyrophosphate build up in the cartilage of joints. Many people have these deposits without any symptoms, and they may only be spotted on an X-ray, where they show as a fine white line in the cartilage. This is called chondrocalcinosis.
Sometimes the crystals shed into the joint and trigger sudden inflammation. This is the condition traditionally called pseudogout, because it looks like gout. Doctors now usually call it acute CPP crystal arthritis. CPPD can also cause a more long-lasting arthritis that looks like osteoarthritis or, less often, rheumatoid arthritis.
Who gets it?
CPPD becomes more common with age and is uncommon before 60. Other things that make it more likely include:
- Existing osteoarthritis or previous joint injury or surgery.
- Some conditions that affect body chemistry, including an overactive parathyroid gland, haemochromatosis (iron overload), and low magnesium levels.
- A family history of early CPPD, which is rare.
If you are diagnosed at a younger age, or have many joints affected, your doctor may check for these conditions with blood tests.
What an attack feels like
An attack of acute CPP crystal arthritis usually comes on over hours to a day or so. The joint becomes painful, swollen, warm and sometimes red, and it can be hard to move or bear weight. The knee is the most common site, followed by the wrist, shoulder, ankle and elbow. You may feel generally unwell or have a mild temperature, which is one reason it can be confused with infection.
Attacks can be triggered by illness, surgery (including operations on other parts of the body), injury to the joint, or sometimes for no clear reason. Untreated, an attack often settles within a few weeks, but treatment speeds recovery.
How it differs from gout
Gout and pseudogout are both crystal arthritis, but the crystals are different.
- Gout is caused by urate crystals and commonly affects the big toe. It is linked to high urate levels in the blood and can be prevented with urate-lowering medicines such as allopurinol.
- Pseudogout is caused by calcium pyrophosphate crystals, more often affects the knee or wrist, and there is currently no medicine that dissolves the crystals.
The two can occur together. Our guide to gout versus pseudogout compares them in more detail.
How it is diagnosed
The most reliable way to diagnose it is to draw fluid from the swollen joint with a needle and look at it under a special microscope for CPP crystals. The fluid is also tested for infection, because septic arthritis can look very similar and can occur at the same time. Removing fluid often eases the pain too.
Other tests may include blood tests for inflammation, calcium, magnesium, iron and parathyroid hormone, and an X-ray or ultrasound to look for crystal deposits in the cartilage.
Treating a flare
The aim is to calm the inflammation quickly. Options your doctor may suggest include:
- Resting the joint for a short time, applying an ice pack wrapped in a towel, and raising the limb.
- Draining fluid from the joint, sometimes followed by a steroid injection into the joint once infection has been ruled out.
- Anti-inflammatory painkillers (NSAIDs), if they are safe for you. Many older people cannot take them because of stomach, kidney or heart risks. See our painkillers and NSAIDs guide.
- Colchicine, which is also used for gout. It can cause diarrhoea and interacts with some other medicines and grapefruit.
- A short course of steroid tablets or an injection, especially when several joints are involved.
Your doctor will choose based on your other health conditions and medicines. Take medicines exactly as prescribed and do not change doses yourself. As the flare settles, gradually get the joint moving again to prevent stiffness.
Long-term management
There is no treatment yet that removes CPP crystals from joints, so long-term care focuses on reducing attacks and keeping joints working.
- If attacks are frequent, your doctor may suggest regular low-intensity preventive medicine, such as colchicine, or refer you to a rheumatologist.
- Treating any underlying condition, such as haemochromatosis or an overactive parathyroid gland, is important.
- Exercise, strengthening and weight management help if you also have osteoarthritis. See our knee pain guide.
- Plan ahead for surgery or illness. Tell your surgical team if you have had attacks, as flares can follow operations.
For older people living with frailty, our guide to pseudogout and frailty covers extra considerations, such as confusion during a flare and staying mobile safely.
Day-to-day tips
- Keep an ice pack in the freezer and know your flare plan, so you can act early.
- Ask your GP or pharmacist in advance which painkillers are safe for you, given your other conditions and medicines.
- Stay active between attacks with regular walking and strengthening, which helps any osteoarthritis in the same joints.
- Stay well hydrated and seek early treatment for infections, as illness can trigger flares.
- If you live alone, plan who could help with shopping or getting about if a knee or ankle flares.
Frequently asked questions
Is pseudogout the same as gout?
No. Both cause sudden joint inflammation, but gout is caused by urate crystals and pseudogout by calcium pyrophosphate crystals. Treatment and prevention differ.
Does diet affect pseudogout?
Unlike gout, pseudogout is not strongly linked to diet. A balanced diet and a healthy weight still help joint health overall.
How long does a pseudogout attack last?
Attacks often settle within a few weeks without treatment, and usually faster with treatment.
Can pseudogout be cured?
There is no treatment that removes the crystals, but flares can be treated and sometimes prevented, and underlying conditions can be managed.
Why did I get pseudogout after an operation?
Surgery and illness can trigger attacks, possibly through changes in body chemistry and stress on the body. Tell your team if it happens.
Is a hot swollen knee always pseudogout?
No. It may be gout, infection or another type of arthritis. A new hot, swollen joint needs a same-day assessment, and urgent care if you have a fever.
Sources and further reading
This guide is for general education and is not a substitute for personal medical advice. Everyone's situation is different, so always follow the advice of your own GP, pharmacist or rheumatology team. If you feel very unwell, call 999 or go to A&E. For urgent advice, contact NHS 111.