Psoriasis affects about 3% of adults in the United States. However, there are various forms of the condition, some of which are more common than others.

The above information comes from a 2021 study published in JAMA Dermatology.

Psoriasis is a chronic, autoimmune skin condition that causes inflammation and scaly patches on the skin. It induces inflammation in the body due to the multiplication of skin cells.

Although psoriasis can appear anywhere on the body, the most common places for these patches include the elbows, knees, scalp, lower back, face, palms, and soles of the feet.

Read on to learn about how common psoriasis is, the prevalence of the different types, and more.

Research from 2021 estimates that 3% of U.S. adults have psoriasis. This equates to more than 7.5 million people.

Further research estimates that psoriasis affects 2–3% of the global population. It most frequently affects people aged 60–69 and people living in high-income countries. Despite this, the National Psoriasis Foundation says that the condition can affect people of all ages and ethnicities, with symptoms often beginning between the ages of 15–25.

Additionally, research from 2017 states that men may have more severe psoriasis than women.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

Psoriasis can occur anywhere on the body, and every individual experiences the condition uniquely. This section explores different types of psoriasis and the prevalence of these forms.

Plaque

This is the most common form of psoriasis. About 80–90% of people with psoriasis experience this form.

A person with plaque psoriasis will develop raised skin patches with silvery or shiny scales. Sometimes, the plaques may look purple, dark brown, or red.

Plaque psoriasis often affects the knees, scalp, elbows, and torso. This form is often symmetrical, affecting the same body parts on either side.

Research states that 15% of individuals with plaque psoriasis will develop psoriatic arthritis, a form of arthritis that affects a body part with psoriasis.

Scalp

Scalp psoriasis is a form of plaque psoriasis. It presents the same symptoms discussed above but only affects the scalp.

This is present in 45–56% of people with the condition, and about 90% of people with psoriasis experience scalp psoriasis at some point.

Genital

This form of psoriasis affects the genital area and the tops of the thighs. It is very common, affecting up to 63% of individuals with psoriasis at some point in their lifetime.

Guttate

Guttate psoriasis is most prevalent in children and young adults. It affects approximately 8% of those with psoriasis.

Symptoms include small, itchy spots which may appear on the arms, legs, or torso. They usually occur as a result of inflammation.

Pustular

A person with pustular psoriasis will experience small, painful lumps filled with pus. These spots will typically have red, purple, or dark brown skin surrounding them.

It is less common than the other forms, affecting about 3% of individuals with psoriasis.

Inverse

Inverse psoriasis is where smooth, inflamed skin develops in folds of the skin. This includes the underarms, genitals, under breasts, and in the buttocks. Rubbing and sweating can worsen the condition.

Inverse psoriasis occurs in 3–7% of people with psoriasis.

Erythrodermic

Erythrodermic psoriasis causes scaly patches on most of the body. People with this form will also experience their skin shedding in large layers. It can cause dehydration, intense itching and pain, and changes in heart rate and temperature.

This type is rare, affecting just 2% of individuals with psoriasis. In some people, it may be life threatening.

Psoriasis can significantly impact a person’s life. The National Health Service (NHS) in the United Kingdom makes some of the following recommendations for individuals living with psoriasis:

  • Self-care: This includes a person getting physical exercise, maintaining a moderate weight, and looking after their physical and mental health.
  • Treatment: A person should take any prescription medications, as necessary, and discuss side effects with a healthcare professional.
  • Reviews: It will often be a requirement for people with psoriasis to review and discuss any new symptoms or concerns with a medical team.
  • Lifestyle changes: This may include stopping smoking, reducing alcohol intake, and managing one’s weight. A person should discuss these lifestyle changes with a healthcare professional.
  • Look after mental health: Anxiety and low confidence are common in those with psoriasis due to the impact on their physical appearance. A person should take note of how they feel and discuss any concerns with a doctor or therapist.

Psoriasis affects approximately 2–3% of the population worldwide. The most common form is plaque psoriasis, but different forms affect different parts of the body in varying levels of severity.

Living with psoriasis can impact a person’s physical and mental health, so it is important to contact a healthcare professional to develop a comprehensive treatment plan.