What is Psoriasis?

Psoriasis is a common skin condition in which red, itchy scaly patches develop on the body. The patches commonly occur on the knees, elbows, trunk and scalp. Psoriasis is a long term condition with no actual cure. Symptoms tend to go through cycles, where they may flare up for a few weeks/months and then subside for a while, possibly going into remission.

Clinical Presentation of Psoriasis

The overall presentation of Psoriasis can vary from person to person. Some common signs include:

  1. Red patches of skin, covered with thick silvery scales
  2. Dry cracked skin
  3. Small scaling spots
  4. Itching, burning, or soreness on skin
  5. Swollen and stiff joints
  6. Thickened nails

The most commonly affected areas include: lower back, knees, elbows, soles of the feet, face, scalp, and the palms.

There are several types of psoriasis, characterized by location.

  1. Plaque psoriasis: This is the most common form, in which dry, raised, and red skin patches appear on the skin. These patches are covered with silvery scales, and may be tender and itchy. These lesions typically appear on the knees, lower back, elbows, and scalp areas.
  2. Nail psoriasis: Psoriasis on the nails can cause abnormal nail growth and discoloration. This may also lead to nails to become loose and separate from the nail bed.
  3. Guttate psoriasis: Guttate psoriasis is characterized by small scaling lesions that develop on the trunk, legs, or arms. This type typically occurs in young adults and children, and often is triggered by a bacterial infection.
  4. Inverse psoriasis: Inverse psoriasis affects skin folds, such as the breast, buttocks, and groin areas. It appears as smooth patches of red skin, and it worsens with friction and sweat. This type of psoriasis can be triggered by fungal infections.
  5. Pustular psoriasis: Pustular psoriasis is rare, but it causes pus-filled lesions that can occur in widespread patches or in smaller areas of the body.
  6. Psoriatic psoriasis: Psoriatic psoriasis causes painful and swollen joints, with potential to cause stiffness and permanent joint damage in serious cases.
  7. Erythrodermic psoriasis: Erythrodermic psoriasis is the least common type of psoriasis. It presents with a red, peeling rash on the entire body and it can cause intense itching and burning.

Causes/Risk Factors of Psoriasis

Psoriasis is thought to be caused by an immune system malfunction, which causes the skin to regenerate and grow at a faster rate than normal. There is no clear cause as to why the immune system develops this problem, but both genetics and environmental factors contribute to the causes of psoriasis.

Common Triggers of Psoriasis

  1. Skin and throat infections
  2. Cold and dry weather conditions
  3. Skin injury, such as a cut, bug bite, or sunburn
  4. Stress
  5. Smoking and Heavy alcohol intake
  6. Medications, such as lithium, antimalarial drugs, and high blood pressure drugs
  7. Rapid withdrawal of corticosteroids

Risk Factors of Psoriasis

  1. Family history: Having parent(s) with psoriasis increases the chance of children developing it as well.
  2. Stress: High stress levels can impact the immune system, potentially causing psoriasis.
  3. Smoking: Smoking increases the risk and severity of psoriasis.

Treatments of Psoriasis

The goal of treatments are to stop skin cells from growing so fast and to remove scales from the skin.

Topical Therapies for Psoriasis

  1. Corticosteroids: Steroids are one of the first line agents for psoriasis. They work by reducing inflammation, suppressing the immune system, and reducing cell growth. The potency and formulation of the corticosteroid depends on where it will be applied, the thickness of the plaques, etc. These medications will be typically applied twice daily. Common side effect of corticosteroids is thinning of the skin.
      in inflammation and immune system activity. It can be combined with corticosteroids, such as Halobetasol, to reduce skin irritation. This medication should not be used during pregnancy and breastfeeding.
      1. Directions: applied once or twice daily
      2. Side effects: skin irritation and increased light sensitivity
    1. Calcineurin inhibitors: Calcineurin inhibitors such as tacrolimus 0.1% and pimecrolimus 1% are effective for treating psoriasis on the face and skin folds. They work by reducing inflammation and reducing plaques. These medications minimize the need to use corticosteroids in sensitive areas. However, they should not be used for long term due to potential increased risk of skin cancer.
      1. Directions: Apply twice daily
      2. Side effects: redness, burning, itching of skin
    2. Coal Tar: Coal tar has been used for years to help treat psoriasis. It helps by reducing inflammation and decreasing cell growth. They are helpful as an addition to corticosteroids and may be compounded into combination creams, ointments, and shampoos.
      1. Directions: Apply once or twice a day
      2. Side effects: staining of hair, skin, and clothing; unpleasant odor

    Other Therapies

    Other therapies to help treat psoriasis include phototherapy, oral medications and injectable biologics.

    1. Phototherapy: Affected skin is exposed to controlled amounts of natural or artificial light. This can help treat patches and reduce cell growth.
    2. Oral Medications: Common oral medications used to treat psoriasis include methotrexate, cyclosporine, and acitretin. These all provide reduction in inflammation and in the rate of cell growth. However, they are commonly used in more severe cases.
    3. Biologics: This group of medications are the newest treatment type for psoriasis. They are injectables and work by altering the immune system. Biologics are recommended to be used after first line topical therapies have failed, as they run the risk for suppressing the immune system, increasing the risk of other serious infections.


    1. Psoriasis. Updated May 2, 2020. Accessed March 26, 2021.
    2. Feldman SR. Treatment of psoriasis in adults. In: Ofori A, ed. UpToDate. UpToDate; 2021. Accessed March 26, 2021.