Psoriatic arthritis is a type of arthritis that develops in some people with the skin condition psoriasis. It typically causes affected joints to become inflamed (swollen), stiff and painful.
Between 20-40% of people with psoriasis will develop psoriatic arthritis. Psoriasis affecting the skin affects around 3% of people.
In most cases, people will experience problems with their skin before they notice any symptoms affecting their joints. In a minority of cases, skin problems may develop after or at the same time as joint problems.
Like psoriasis, psoriatic arthritis is thought to be a result of the immune system mistakenly attacking healthy tissue. It's not clear why some people with psoriasis develop psoriatic arthritis and others don't.
Signs and symptoms
The pain, swelling and stiffness associated with psoriatic arthritis can affect any joint in the body, but the condition often affects particular areas including the
- neck and spine
Tendons can also be involved – in some people they may be the major problem.
Symptoms usually develop slowly meaning that many people are unaware that they are developing psoriatic arthritis. In rarer cases, symptoms can develop suddenly and without warning.
The severity of the condition can vary considerably from person to person. Some people may have severe problems affecting many joints, whereas others may only notice mild symptoms in one or two joints.
There may be times when your symptoms improve and periods when they get worse (known as flare-ups or relapses). Some people may reach a point where they have no symptoms at all (known as remission).
Relapses can be very difficult to predict, but can often be managed with medication when they happen.
When to seek medical advice
You should speak to your GP if you experience constant pain, swelling or stiffness in your joints – even if you haven't been diagnosed with psoriasis.
If you have been diagnosed with psoriasis, you should have check-ups at least once a year to monitor your condition. Make sure you let your doctor know if you're experiencing any problems with your joints.
Diagnosing psoriatic arthritis
If your doctor thinks you may have arthritis, they should refer you to a rheumatologist (a specialist in joint conditions) for an assessment.
A rheumatologist will usually be able to diagnose psoriatic arthritis if you have psoriasis and problems with your joints, and other types of arthritis – such as rheumatoid arthritis and osteoarthritis – have been ruled out.
A number of tests may be carried out to help confirm a diagnosis, including blood tests to check for signs of inflammation in your body and the presence of certain antibodies found in other types of arthritis, as well as X-rays or scans of your joints.
Treating psoriatic arthritis
The main aims of treatment will be to relieve your symptoms, slow the progression of the condition and improve your quality of life.
For most people, this will involve trying a number of different medications, some of which can also treat the psoriasis. Ideally, you should take one medication to treat both your psoriasis and psoriatic arthritis whenever possible.
The main medications used to treat psoriatic arthritis are summarised below.
Non-steroidal anti-inflammatory drugs (NSAIDs)
Your GP may first prescribe non-steroidal anti-inflammatory drugs (NSAIDs) to see if they help relieve pain and reduce inflammation.
There are two types of NSAIDs and they work in slightly different ways:
- traditional NSAIDs, such as ibuprofen, naproxen or diclofenac
- COX-2 inhibitors (often called coxibs), such as celecoxib or etoricoxib
Like all medications, NSAIDs can have side-effects, but your doctor will take precautions to reduce the risk of these, such as prescribing the lowest dose necessary to control your symptoms for the shortest time possible.
If side-effects do happen, they usually affect the stomach and intestines, and can include indigestion and stomach ulcers. A medication called a proton pump inhibitor (PPI) that helps protect your stomach by reducing the amount of acid it produces will therefore often be prescribed alongside NSAIDs.
If NSAIDs alone are not helpful, some of the medications below may be recommended.
Steroid medication (corticosteroids)
Like NSAIDs, corticosteroids can help reduce pain and swelling.
If you have a single inflamed or swollen joint, your doctor may inject the medication directly into the joint. This can offer rapid relief with minimal side effects, and the effect can last from a few weeks to several months.
Corticosteroids can also be taken as a tablet, or as an injection into the muscle, to help when lots of joints are inflamed. However, doctors are generally cautious about this because the medication can cause significant side effects if used in the long term, and psoriasis can flare up when you stop using it.
Disease-modifying anti-rheumatic drugs (DMARDs)
Disease-modifying anti-rheumatic drugs (DMARDs) are medications that work by tackling the underlying causes of the inflammation in your joints. They can help to ease your symptoms and slow the progression of psoriatic arthritis. The earlier you start taking a DMARD, the more effective it will be.
Psoriatic arthritis can be treated with a variety of DMARDs including:
- Antimalarials (such as hydroxychloroquine)
Your rheumatologist will discuss the most appropriate choice of DMARD for you.
It can take several weeks or months to notice a DMARD working. Therefore, it's important to keep taking the medication, even if it doesn't seem to be working at first.
DMARD therapy is monitored according to guidelines such as British Society for Rheumatology (BSR).
Biological treatments are a newer form of treatment for psoriatic arthritis. You may be offered one of these treatments if:
- your psoriatic arthritis has not responded to at least two different types of DMARD
- you are not able to be treated with at least two different types of DMARD because of other problems e.g. other diseases.
Biological drugs work by directly blocking the chemicals in the blood, skin and joints that switch the immune system on, leading it to attack the lining of your joints and your skin.
Some of the biological medicines you may be offered are adalimumab, certolizumab, etanercept, infliximab and golimumab injections. See our page on treating psoriasis for more information about these medications. Newer biological drugs include ustekinumab.
The most common side-effect of biological treatments is a reaction in the area of skin where the medication is injected, such as redness, swelling or pain, although these reactions aren’t usually serious.
However, biological treatments can sometimes cause other side-effects, including problems with your liver, kidneys or blood count, so you'll usually need to have regular blood or urine tests to check for these.
Biological treatments can make you more likely to develop infections, so you should tell your doctor as soon as possible if you develop symptoms of an infection, such as a sore throat, a high temperature (fever), urinary problems or diarrhoea.
Biological treatments usually take between 2 and 6 months to take effect.
If it's effective, the medication can be continued. Otherwise, your doctor may suggest stopping the medication or swapping to an alternative biological treatment.
There isn't enough scientific research evidence to say that complementary therapies, such as balneotherapy (bathing in water containing minerals), works in treating psoriatic arthritis.
There is also not enough evidence to support taking any kind of food supplement as treatment.
Complementary therapies can sometimes react with other treatments, so you should talk to your GP, specialist or pharmacist if you're thinking of using any.
Managing related conditions
As with psoriasis and other types of inflammatory arthritis, you may be more likely to get some other conditions – such as cardiovascular disease (CVD) – if you have psoriatic arthritis. CVD is the term for conditions of the heart or blood vessels, such as heart disease and stroke.
Your doctor should carry out tests each year (such as blood pressure and cholesterol tests) so they can check whether you have CVD and offer additional treatment, if necessary.
You can also help yourself by:
Read more about living with psoriasis and preventing CVD.
Psoriatic arthritis can also cause inflammation of the eyes, such as Conjunctivitis and Iritis.
If psoriatic arthritis affects your skin and joints, you may notice changes in your nails such as:
- loosening from the nail bed
This is less common if only your skin is affected.
Your care team
As well as your GP and a rheumatologist, you may also be cared for by:
- a specialist nurse – who will often be your first point of contact with your specialist care team
- a dermatologist (skin specialist) – who will be responsible for treating your psoriasis symptoms
- a physiotherapist – who can devise an exercise plan to keep your joints mobile
- an occupational therapist – who can identify any problems you have in everyday activities and find ways to overcome or manage these
- a psychologist – who can offer psychological support if you need it
- a podiatrist who can offer assessment and advice on foot problems if affected during the course of PSA.
Like psoriasis, psoriatic arthritis is a long-term condition that can get progressively worse.
In severe cases, there is a risk of the joints becoming permanently damaged or deformed, which may require surgical treatment.
However, with an early diagnosis and appropriate treatment, it's possible to slow down the progression of the condition and minimise or prevent permanent damage to the joints.