Gout vs Pseudogout (CPPD): What's the Difference?
Two Different Crystals, Often Impossible to Tell Apart by Symptoms Alone
Gout and pseudogout can look and feel almost identical — sudden, hot, swollen, painful joints caused by two completely different crystals. Here's what actually separates them, and why symptoms alone usually can't.
The Quick Answer
Gout is caused by monosodium urate crystals; pseudogout — more accurately called CPPD (calcium pyrophosphate deposition) — is caused by a completely different crystal, calcium pyrophosphate. Both can cause a sudden, hot, swollen, severely painful joint that comes on within hours, and research directly comparing the two describes telling them apart on symptoms alone as "often clinically impossible." A confident diagnosis usually needs a clinical assessment, and sometimes a sample of joint fluid examined under a microscope.
Different Crystals
Urate crystals cause gout; calcium pyrophosphate crystals cause CPPD/pseudogout — genuinely separate conditions.
Similar Symptoms
Sudden pain, swelling, warmth and redness look almost the same in both — that overlap is the whole point of this page.
Joint Patterns, Not Rules
The big toe is typical of gout and the knee of CPPD — but both are tendencies, not proof, and either can affect the other.
Testing Matters
A confident diagnosis usually needs clinical assessment, and sometimes joint fluid checked under a microscope.
What Is Gout?
Gout is a form of inflammatory arthritis caused by monosodium urate crystals forming in and around a joint, usually when uric acid levels in the blood have been running high. It typically causes sudden, severe joint pain and swelling, classically in the big toe, though it can affect other joints too. Our beginner's guide and what causes gout guide cover this in full — this page focuses specifically on how gout compares with a different condition, not on re-explaining gout itself.
What Is Pseudogout / CPPD?
CPPD (calcium pyrophosphate deposition) is the name for the underlying disease process — calcium pyrophosphate crystals building up in and around a joint. "Pseudogout" is the older, more familiar term, but it's more precise to think of it as the name for one particular presentation of CPPD: a sudden, painful, inflamed joint caused by these crystals, more accurately called acute CPP crystal arthritis. Current UK and international rheumatology guidance has moved toward this more precise terminology, though "pseudogout" remains the term most people search for and is still widely used by clinicians and NHS services alongside it.
Importantly, not everyone with CPPD ever has an acute attack. Calcium pyrophosphate deposits (sometimes visible on an X-ray as a fine calcified line in cartilage, called chondrocalcinosis) are very common with age and are often found incidentally, with no symptoms at all. Having deposits on an X-ray doesn't mean a current joint problem is caused by them.
The Main Difference: Different Crystals
The genuine, underlying difference between gout and pseudogout is the crystal involved. Gout is caused by needle-shaped monosodium urate crystals. CPPD is caused by calcium pyrophosphate crystals, which typically look rhomboid or rod-shaped under a microscope. Examined under a specialised polarised-light microscope, the two crystal types behave differently, which is exactly how a laboratory can tell them apart — but that's a lab finding, not something visible to the naked eye or something a reader can assess for themselves. It isn't a difference you or a doctor can see or feel from the outside during an attack.
Gout vs Pseudogout Symptoms
Both conditions can cause a joint that becomes painful, swollen, warm, and stiff or hard to move within a matter of hours — and in both, the skin over the joint can look red, darker, or otherwise changed in colour, which can be harder to notice on darker skin tones and is still worth checking for warmth and swelling rather than colour alone. Research directly comparing the two has described distinguishing gout from acute CPP crystal arthritis on clinical grounds as "often clinically impossible" — the symptom pictures genuinely overlap that much.
There is no reliable symptom pattern that proves gout rather than pseudogout, or the reverse, in an individual case. This page doesn't provide one, because a trustworthy one doesn't exist — that's exactly why testing matters (see below).
Which Joints Are Usually Affected?
Gout classically affects the big toe (see our gout in the big toe guide), but it commonly affects the ankle, foot, knee, wrist, hand and elbow too. CPPD most typically affects the knee, followed by the wrist, shoulder, ankle and elbow. These are genuine, real population-level patterns — but they're tendencies, not rules for an individual attack. Gout in the knee or wrist is well documented, and CPPD affecting the big toe, while uncommon, is also documented in the medical literature. A big-toe attack doesn't prove gout, and a knee or wrist attack doesn't prove CPPD.
Gout vs Pseudogout (CPPD) Comparison
This table summarises the genuine differences between the two conditions. It's a reference for understanding, not a self-diagnosis tool — an individual attack can't be reliably placed into one column just by matching symptoms against it.
| What | Gout | Pseudogout (CPPD) |
|---|---|---|
| Crystal involved | Monosodium urate (needle-shaped) | Calcium pyrophosphate (rhomboid/rod-shaped) |
| Typical joints | Big toe classically, also ankle, foot, knee, wrist, hand | Knee most commonly, also wrist, shoulder, ankle, elbow |
| Onset | Sudden, peaks within hours | Sudden, peaks within hours — very similar timing |
| Age and sex pattern | More common in men; rises in women after menopause | Becomes more common with age in both sexes; affects men and women in broadly similar numbers |
| Uric acid (blood test) | Often, but not always, raised — can be normal during an attack | Not typically raised because of CPPD itself |
| How it's confirmed | Clinical assessment; joint fluid microscopy if uncertain | Clinical assessment; joint fluid microscopy if uncertain |
| Imaging clue | Not usually specific | Chondrocalcinosis (a calcified line in cartilage) may be visible on X-ray, but isn't proof the current attack is CPPD |
| Long-term treatment | Urate-lowering medication is available and widely used to prevent future attacks | No direct equivalent exists; frequent flares are sometimes managed with preventive low-dose colchicine |
Can Uric Acid Tell the Difference?
Not reliably. A high uric acid (urate) level is common in the general population and doesn't by itself confirm gout, let alone rule out CPPD — someone can have a raised urate reading and still be having a CPPD flare. Just as importantly, urate can be normal, or even low, during an actual gout attack, which is why UK guidance recommends repeating the blood test a few weeks after a flare has settled if the level looks normal but gout is still suspected. Our uric acid and gout guide covers what the test does and doesn't tell you in more detail. A single urate result, taken on its own, cannot reliably separate gout from pseudogout.
How Doctors Tell Them Apart
Diagnosis usually starts with a clinical history and examination, though as covered above, this alone often can't distinguish the two with confidence. Where the picture is genuinely a first, classic presentation with clear risk factors, a doctor may reasonably diagnose gout clinically without further testing. Where it's uncertain — a first attack, an unusual joint, or a case that isn't responding as expected — a sample of fluid can be taken from the joint and examined under a polarised-light microscope, which is the most reliable way of confirming which crystal is actually present. Imaging such as X-ray or ultrasound can add supporting information (for example, chondrocalcinosis suggesting CPPD deposits are present), but on its own isn't considered diagnostic of what's causing a specific attack.
What About Septic Arthritis?
A sudden, hot, swollen, severely painful joint isn't only ever gout or pseudogout — it can also mean a joint infection (septic arthritis), which is a medical emergency. UK clinical guidance is direct on this point: a joint like this should be treated as a possible infection until proven otherwise, because untreated infection can damage a joint quickly. Crystals being found in a joint fluid sample doesn't rule out infection either — the two can occasionally occur together, which is one reason clinicians test for infection even when crystals are also present.
A joint is hot, very swollen and rapidly worsening — especially with fever, feeling generally unwell, a break in the skin near the joint, or if you're on medication that weakens your immune system or have a joint replacement. Most sudden joint episodes turn out to be gout or CPPD, but only an assessment — often including a joint fluid test — can be sure, so don't wait it out.
Are Gout and Pseudogout Treated the Same Way?
Treating an acute attack overlaps substantially between the two — anti-inflammatory medicines, colchicine, or a short course of corticosteroids are used for both, since the goal in the moment is calming inflammation regardless of which crystal caused it. See our gout treatment guide for how acute gout flares and long-term gout medication work.
Long-term management is where they genuinely diverge. Gout has a well-established long-term option — urate-lowering medication, taken continuously to bring uric acid down and prevent future attacks. CPPD doesn't have a direct equivalent; there's currently no medication that removes calcium pyrophosphate deposits or reliably stops them forming. For people who have frequent CPPD flares, a doctor may sometimes suggest a low daily dose of a preventive medicine to reduce how often attacks happen, but this manages the flares rather than the underlying deposits.
Can You Have Both Gout and CPPD?
Yes — having both is documented in the medical literature, including cases where both crystal types are found in the same joint. It isn't considered common, and there isn't a reliable figure for exactly how often it happens, so we won't invent one here. Practically, it's worth knowing that both conditions become more common with age and share some of the same risk factors, such as joint damage and osteoarthritis, so a past gout diagnosis doesn't rule out a new CPPD flare later on, and vice versa.
What Should You Do If You're Not Sure Which You Have?
Get the joint assessed rather than trying to work it out yourself — this page is designed to help you understand the conversation with a doctor, not to replace it. This matters more, not less, if it's your first attack, if it's affecting an unusual joint for you, or if a previous gout diagnosis doesn't seem to explain what's happening this time. Mentioning that you're aware gout and pseudogout can look alike is a reasonable, useful thing to say to whoever assesses you, since it may prompt a joint fluid test if there's genuine uncertainty.
Common Myths About Gout and Pseudogout
"It's basically the same thing, just a weaker version."
They're separate diseases caused by different crystals, with different typical joints and different long-term treatment — not a strong-vs-weak version of the same thing.
"My uric acid is high, so it can't be pseudogout."
Raised uric acid is common in the general population and doesn't rule out a CPPD flare happening at the same time.
"It's my knee, so it must be pseudogout."
These are common patterns, not diagnostic rules. Gout affects the knee and wrist too, and CPPD can, uncommonly, affect the big toe.
"I can just tell which one it is from how it looks and feels."
Research directly comparing the two describes telling them apart on symptoms alone as often clinically impossible — a confident answer usually needs assessment, sometimes including a joint fluid test.
"The scan showed calcium in my joint, so that settles it."
Calcium pyrophosphate deposits are common with age and are often silent. Finding them on an X-ray doesn't confirm they're what's causing a specific current attack.
Frequently Asked Questions
Is pseudogout the same as gout?
No. They cause very similar symptoms, but they're different diseases caused by different crystals — monosodium urate in gout, calcium pyrophosphate in pseudogout/CPPD.
What does CPPD stand for?
Calcium pyrophosphate deposition — the more precise, current name for the condition often still called pseudogout, particularly when it causes an acute attack.
Can pseudogout affect the big toe?
It can, though it's uncommon — the big toe is far more typical of gout. A big-toe attack is more likely to be gout, but it isn't automatic proof.
Does gout ever affect the knee or wrist?
Yes, regularly. The knee and wrist are common gout sites too, even though CPPD favours them slightly more at a population level.
Can a blood test tell gout and pseudogout apart?
Not reliably on its own. Uric acid can be normal during a gout attack, and can be raised in someone who doesn't have gout at all.
How is pseudogout actually diagnosed?
Through clinical assessment, and where there's uncertainty, by examining a sample of joint fluid under a polarised-light microscope to identify the crystal type.
Is joint fluid testing always needed?
No — a classic, typical presentation can sometimes be diagnosed clinically. It becomes more important when the diagnosis is genuinely uncertain, or infection needs to be ruled out.
Are gout and pseudogout treated the same way?
Acute attacks are treated similarly, with anti-inflammatory approaches. Long-term management differs, since gout has urate-lowering medication and CPPD doesn't have a direct equivalent.
Is there a long-term medicine for pseudogout like allopurinol for gout?
No — there's currently no medicine that removes calcium pyrophosphate deposits. Frequent flares are sometimes managed with a preventive low daily dose of a different medicine instead.
Can someone have both gout and pseudogout?
Yes, this is documented, though it isn't common and there's no reliable figure for exactly how often. Both become more likely with age.
Is pseudogout serious?
A single attack is usually manageable and settles with treatment, similar to gout. As with gout, getting it properly assessed matters, partly to rule out other causes like infection.
When should I get an attack checked urgently?
If a joint is hot, very swollen and rapidly worsening, especially with fever or feeling generally unwell — this needs prompt assessment to rule out joint infection.
This guide is for general educational purposes and explains the difference between gout and pseudogout (CPPD) in outline — it is not personal medical advice and cannot diagnose which condition you have, or rule out other causes such as infection. Never assume a diagnosis from this page alone, and never start, stop or change a prescribed medicine based on it. Always speak with your own doctor about diagnosis and treatment, and seek prompt medical attention for a hot, rapidly worsening joint.