What is psoriatic arthritis?

Psoriatic arthritis causes inflammation in and around the joints. It usually affects people who already have psoriasis, a skin condition that causes a red, scaly rash, especially on the elbows, knees, back, buttocks and scalp. However, some people develop the arthritic symptoms before the psoriasis, while others will never develop the skin condition.

Psoriasis can affect people of any age, both male and female, but psoriatic arthritis tends to affect more adults than young people.

People with psoriasis may also have other types of arthritis, such as osteoarthritis or rheumatoid arthritis, but these aren't linked to the psoriasis.

Symptoms

Symptoms of psoriatic arthritis can include:

  • pain and stiffness in and around your joints
  • swollen fingers or toes (dactylitis), caused by inflammation in both joints and tendons
  • buttock pain, a stiff back or a stiff neck, which is caused by inflammation in your spine (spondylitis)
  • pain and swelling in your heels, caused by inflammation where the Achilles tendon attaches to the bone
  • pain in other areas where tendons attach to bone (enthesitis), such as your knee, hip and chest
  • pitting, discoloration and thickening of your nails
  • fatigue, which can be caused by the activity of the disease and the emotional effects that come with living with a long-term condition.

Three diagrams and photographs displaying the symptoms of psoriatic arthritis.

Psoriatic arthritis can affect any of the 78 joints in the body, although some joints are more likely to be affected than others. About one in four people who have psoriatic arthritis will have pain and stiffness in their neck or back.

An illustration of the whole body, highlighting the different areas which are commonly affected by psoriatic arthritis.

Does psoriatic arthritis affect other parts of the body?

Psoriatic arthritis doesn't usually affect major organs such as the liver or lungs. However, you may be more likely to develop a painful red eye. If this affects you, it's important not to ignore it.

These symptoms may be caused by a condition called uveitis, also known as iritis, which is inflammation at the front of the eye. This can damage your eyesight if untreated.

Discuss this with your doctor who should help you recognise these symptoms, and explain what you should do if it occurs. People with psoriasis and psoriatic arthritis may also have a slightly greater risk than other people of developing heart disease, so it's important to address anything that could add to this risk, such as

  • smoking
  • high alcohol intake
  • being overweight
  • blood pressure problems.

Causes

The arthritis and the skin condition are both caused by inflammation. The processes of inflammation are very similar in the skin and the joints.

We don't yet know exactly what triggers the inflammation in psoriatic arthritis, although a particular combination of genes makes some people more likely than others to develop psoriasis and psoriatic arthritis.

Research suggests that something – perhaps an infection – acts as a trigger in people who are already at risk of this type of arthritis because of the genes they've inherited from their parents. No specific infection has yet been found, and it may be that a variety of infections can trigger the disease, for example bacteria that live in patches of psoriasis.

Sometimes the arthritis can follow an accident or injury, particularly if it affects a single joint. People who are overweight are more at risk of developing both psoriasis and the arthritis linked with this.

How will psoriatic arthritis affect me?

Psoriatic arthritis can vary a great deal between different people so it’s not possible to offer specific advice on what you should expect.

About a third of people with psoriatic arthritis will have a mild form of the disease that remains very stable over time. Others will have more severe symptoms that need long-term treatment. How bad the arthritis is isn't related to how bad the skin condition is – some people with very mild psoriasis can have severe arthritis.

Psoriatic arthritis will usually have some effect on function and quality of life, but treatment will help to reduce the effects it has.

Diagnosis

It's important that psoriatic arthritis is diagnosed early so treatment can be started as soon as possible.

There's no specific test for psoriatic arthritis, but the diagnosis is based on your symptoms and a physical examination. Your doctor will check for psoriasis and may ask if there's a history of psoriasis or psoriatic arthritis in your family.

People with psoriasis may be regularly asked about joint symptoms by their GP and/or dermatologist.

If several joints are affected, your doctor will consider features such as the pattern of arthritis – that is, which joints are affected.

It can be difficult to tell the difference between psoriatic arthritis and rheumatoid arthritis, but blood tests such as those for rheumatoid factor and anti-CCP antibody can help.

Psoriatic arthritis can have similar symptoms to gout, so x-rays of your back, hands and feet may also be helpful, as psoriatic arthritis can affect the bones and joints in these areas in a different way to other conditions.

Other types of imaging, such as MRI and ultrasound scans, may help to confirm the diagnosis.

The National Institute for Health and Care Excellence (NICE) published new quality standards in 2013 to help improve the care of people across England with psoriasis.

The standards are mainly aimed at GPs and state that people with psoriasis should be offered an appointment every year to check for signs of psoriatic arthritis and every five years to check their cardiovascular health. This should help in diagnosing psoriatic arthritis as early as possible and making sure that the right treatment is started.

Treatment

A team of healthcare professionals are likely to be involved in your treatment. Your doctor (usually a rheumatologist) will be responsible for your care, although a specialist nurse may also be involved in monitoring your condition and treatments.

You may also see:

  • a physiotherapist, who can give you advice on exercises to help maintain your mobility
  • an occupational therapist, who can give you advice on protecting your joints from further damage, for example, by using splints or altering the way you perform tasks to reduce the strain on your joints
  • a podiatrist, who can assess your footcare needs and offer advice on special footwear.

Treatments for the arthritis

Non-steroidal anti-inflammatory drugs (NSAIDs) act by blocking the inflammation that occurs in the lining of your joints. They can be very effective in controlling pain and stiffness. Usually you'll find your symptoms improve within hours of taking these drugs but the effect will only last for a few hours, so you have to take the tablets regularly.

Some people find that NSAIDs work well at first but become less effective after a few weeks. In this situation, it sometimes helps to try a different NSAID. There are about 20 available, including ibuprofen, diclofenac, indometacin and naproxen.

Like all drugs, NSAIDs can have side-effects, so your doctor will reduce the risk of these, by prescribing the lowest effective dose for the shortest possible period of time.

NSAIDs can cause digestive problems (stomach upsets, indigestion or damage to the lining of the stomach) so in most cases NSAIDs will be prescribed along with a drug called a proton pump inhibitor (PPI), such as omeprazole, that will help to protect the stomach.

NSAIDs also carry an increased risk of heart attack or stroke. Although the increased risk is small, your doctor will be cautious about prescribing NSAIDs if there are other factors that may increase your overall risk, for example, smoking, circulation problems, high blood pressure, high cholesterol or diabetes.

Disease-modifying anti-rheumatic drugs (DMARDs) tackle the causes of inflammation. They change the way the disease progresses and hopefully will stop your arthritis from getting worse. It may be several weeks before DMARDs start to have an effect on your joints, so you should keep taking them even if they don't seem to be working. Sometimes these drugs are given by injection.

The decision to use DMARDs will depend on a number of factors, including how active the arthritis and psoriasis are and the likelihood of joint damage.

Examples of DMARDs include:

Biological therapies are newer drugs that may be used if other DMARDs aren’t working well. These are given by injection into the skin or through a drip into a vein (an intravenous infusion). Biological therapies used for treating psoriatic arthritis include:

When taking almost all DMARDs you’ll need to have regular blood tests at your GP's practice, and in some cases a urine test. The tests allow your doctor to monitor the effects of the drug on your condition but also to check for possible side-effects, including problems with your liver, kidneys or blood count.

You can take NSAIDs along with DMARDs, and some people may need to take more than one DMARD at a time.

Steroid injections are often recommended for joints that are particularly troublesome or when ligaments and tendons become inflamed. When steroids are used for people with psoriasis and psoriatic arthritis, there's a risk that the psoriasis can get worse. You should discuss this with your doctor if steroids are suggested.

However, steroid tablets aren't generally used for psoriatic arthritis.

Managing your symptoms

Learn more how to manage the symptoms of psoriatic arthritis.

Exercise

Inflammation can lead to muscle weakness and stiffness in the joints. Exercise is important to prevent this and to keep your joints working properly.

However, inflammation can also make you feel unusually tired so you may find you need to take more rests than usual.

Your doctor or a physiotherapist will be able to advise on suitable forms of exercise depending on which joints are most affected. However, you'll need to find out for yourself the right balance between rest and exercise.

Living with psoriatic arthritis

Any long-term condition can affect your moods and confidence, and it can have an impact on your work, social life and relationships. Talk things over with a friend, relative or your doctor if you do find your condition is getting you down.

You can also contact support groups if you want to meet other people with psoriatic arthritis.

Sex and pregnancy

Sex can sometimes be painful, particularly for a woman whose hips are affected. Experimenting with different positions will usually provide a solution.

Psoriatic arthritis won't affect your chances of having children. The arthritis may improve during the pregnancy, although your symptoms may return after the baby is born.

Some of the drug treatments given for psoriatic arthritis should be avoided when trying to start a family. For instance, sulfasalazine can cause a low sperm count (this isn't permanent) and you shouldn't try for a baby if you're on methotrexate, or retinoids, or have been using them in recent months.

If you're thinking about starting a family, you should discuss your drug treatment with your doctor well in advance so that your medications can be changed if needed.

Both psoriasis and psoriatic arthritis do tend to run in families to some extent. If there’s a history of psoriasis or psoriatic arthritis in your family, your children may be more likely than most to get psoriatic arthritis, but the risk of passing it on directly is still low.