Psoriasis can affect your knees, but it’s usually limited to two specific types.

More than 7.5 million adults in the United States have psoriasis, according to a 2021 study.

In its most common form, called plaque psoriasis, a problem with the immune system causes the body to produce skin cells more quickly than they shed. This results in thick, scaly patches of skin called plaques.

You can develop psoriasis on your knees.

Another form of psoriasis called psoriatic arthritis (PsA) causes painful swelling inside a joint or where tendons and ligaments connect to bone. PsA can affect your knees and other joints.

There are five types of psoriasis that cause rashes on the skin. Two of them are likely to form on the knees. PsA can also affect the knees by causing pain and swelling.

Plaque psoriasis on knees

Plaque psoriasis is the most common type of psoriasis. It causes patches of red, purple, or violet skin with silvery white or gray scales, depending on skin tone. These scales generally appear on the elbows, knees, torso, scalp, and face.

Pustular psoriasis

Pustular psoriasis causes red or brown patches of pus-filled bumps. It most commonly appears on the hands and feet, but one rare form can appear on the whole body.

Psoriasis patches may look different from person to person, but they do share some common traits. An outbreak on the knees may include:

  • thickened red, purple, or violet skin with silvery white or gray scales
  • skin that itches or burns
  • dry or cracked skin

Psoriasis tends to flare up and calm down again: Patches will develop and then clear up for a period of time before returning.

Psoriasis occurs when the body’s immune system causes it to produce too many skin cells too quickly.

Researchers do not fully understand what causes the immune system problem but think it’s a combination of genetics and environmental triggers. Many people with psoriasis have a family history of the condition.

Some things that might contribute to developing psoriasis include:

A form of psoriasis called inverse psoriasis develops in folds of skin, like the armpits, groin, and between the buttocks. You’re more likely to get it behind your knees than other forms of psoriasis.

About 21% to 30% of people with psoriasis develop inverse psoriasis, according to the National Psoriasis Foundation.

On darker skin tones, inverse psoriasis appears in skin folds as purple or brown patches. On lighter skin tones, the patches may appear bright red. In all cases, the patches may also look smooth and shiny.

About 15% of people with psoriasis develop psoriatic arthritis (PsA), according to the American College of Rheumatology. Some people can develop PsA without ever having psoriasis.

Like psoriasis, PsA is also an autoimmune disease that causes the body to attack joints, causing inflammation. This results in swelling, pain, and stiffness. Pitting can also occur in fingernails and toenails.

PsA can develop in any joint or anywhere where tendons and ligaments connect to bone. You do not have to have a psoriasis flare-up on your knee first to develop PsA.

PsA can cause enough inflammation in joints to permanently destroy the joints.

Treatment for psoriasis of the knees focuses on the type of psoriasis breakout and its severity.

At-home treatments

At-home treatment options for psoriasis are most effective when used alongside other treatments, like medications. At-home treatments include:

Over-the-counter treatments

There are several over-the-counter (OTC) treatments for psoriasis. These usually work best if you have a mild case, except for moisturizer. Moisturizers can benefit anyone.

OTC treatments include:

Medical treatments

A doctor may prescribe topical medications, like corticosteroid creams or lotions, or vitamin D3 as treatments for psoriasis. Additionally, they may prescribe therapies or medications like:

Psoriatic arthritis treatments

Treatment for PsA varies depending on the severity of your pain and swelling in your joints. These treatments may include:

If you think you may have psoriasis, reach out to a doctor to get a diagnosis and start treatment.

If you already have a diagnosis of psoriasis, talk with a doctor if symptoms are worsening or treatments you already tried are not working.

Psoriasis is a problem with the immune system that causes your body to produce skin cells more quickly than it sheds them. This results in thick, scaly patches of skin on the elbows, knees, face, back, palms, and feet.

Some people develop arthritis in their joints, called psoriatic arthritis. It causes inflammation in the joints or where tendons and ligaments connect to bones.

Psoriasis can develop on the knees or, rarely, the backs of the knees. Treatment will depend on what type of psoriasis develops and the outbreak’s severity.