Up to 30 percent of people who have psoriasis will also develop a related joint condition called psoriatic arthritis (PsA), suggests a 2013 study including 949 people with plaque psoriasis. This is likely related to the inflammatory response in the body that contributes to both conditions.

Your immune system’s job is to protect your body from harmful invaders. In inflammatory conditions like psoriasis and PsA, your immune system gets mixed up and targets otherwise healthy parts of the body. This can cause damage if inflammation persists.

With psoriasis, this atypical immune response targets skin cells. With PsA, it targets the joints.

When you’re living with psoriasis, it’s important to watch for changes in your joints. Early diagnosis and treatment of PsA can help you better manage symptoms and prevent joint damage.

Here’s what to look out for.

PsA can affect one or more of your joints and lead to symptoms like pain and swelling. You may also notice redness or warmth in the joints.

It can affect any joint in the body, but commonly affects smaller joints in the:

  • fingers
  • hands
  • wrists
  • toes
  • feet
  • knees

These symptoms are caused by the overactive immune response that targets otherwise healthy joints.

When the immune system responds, it increases blood flow to the area to help battle what’s perceived as an invader. But when the “invader” is actually your own body, it can lead to damage.

Another sign of PsA is joint stiffness. You may feel like you don’t have as much movement or mobility in certain joints. This makes it harder to move around.

You may feel especially stiff first thing in the morning or after sitting for long periods. This feeling is often referred to as morning stiffness.

PsA can also cause a whole finger or toe to swell up. This is known as dactylitis. People with this condition describe their fingers or toes as looking like little sausages.

Dactylitis can affect one or more fingers or toes. It can be painful and may interfere with your use of your hands and feet.

In the body, connective tissue called enthesis joins ligaments to bone. Sites of enthesis in the body include the:

  • heel
  • elbow
  • bottom of the foot

PsA can lead to inflammation in the enthesis. When the enthesis becomes inflamed, it’s called enthesitis.

Enthesitis can cause swelling and pain in these areas that gets worse with movement.

PsA can lead to inflammation and pain in the joints that make up your spine. Any part of your back can be affected, but it’s most often the lower part of the back, called the lumbar spine.

When PsA targets the spine, it’s called spondylitis.

Symptoms of spondylitis are often worse when you first get up in the morning or if you spend a lot of time in the same position during the day. Some people also experience decreased flexibility and mobility.

PsA is known to affect the nails. Around 80 percent of people living with PsA experience changes to their nails, known as nail involvement.

You may notice nail symptoms like:

  • pitting
  • grooves
  • thickening
  • separation from the nail bed

These symptoms can affect both the fingernails and toenails.

PsA can also affect your eyes.

This happens when it triggers the immune system to attack the uvea. The uvea is the part of the eye between the white of the eye and the retina.

Inflammation in the uvea is called uveitis. Symptoms of uveitis include:

  • blurry vision
  • redness
  • pain
  • light sensitivity

If you notice any changes to your eyes or vision, get them checked out right away. Left unmanaged, uveitis can cause permanent vision loss.

People living with psoriasis have an increased risk of developing PsA. Be on the lookout for symptoms like joint pain, stiffness, and swelling, as well as changes that affect your eyes and nails.

Left untreated, PsA can lead to permanent joint damage. It’s important to get treatment early to preserve joint structure and function.