Psoriasis is a common skin disorder marked by raised, inflamed lesions that join together to form plaques with distinct borders on the skin and may be covered with flaky scales. It can also exist as small, scaly droplet-like lesions (guttate psoriasis). A wide range of medications may be used to treat psoriasis. The type of psoriasis medication prescribed depends on several factors, including:

• Type of psoriasis present
  
  
• Location of lesions on the body
  
  
• Severity of psoriasis present
  
  
• Patient’s overall health, age and medical history
  
  
• Patient’s tolerance of specific medications, procedures or therapies
  
  
• Patient and physician’s opinion or preference

Topical medications are usually the first treatment choice for psoriasis. Topical treatments, such as creams and ointments, are placed on the skin surface, as opposed to medications that are taken orally or injected (systemic). They may be used to slow or normalize the growth rate of skin cells and reduce inflammation associated with mild to moderate psoriasis. They may be used alone, in combination with each other, oral or injected medications, or with controlled exposure to ultraviolet light (phototherapy). Generally, any scales present need to be removed before application because they block medication penetration. Combining topical medications that include urea, salicylic acid or vitamin D often accomplishes this.

Some psoriasis medications are available in both topical and oral forms. Oral medications may be used for severe, life-threatening cases of psoriasis that do not respond to other forms of treatment. They may be used alone or in combination with topical, other oral or injected medications. These are more dangerous than topical treatments as some may cause life-threatening complications. Therefore their benefits of use must be weighed against the possible side effects. Psoriasis medications may also sometimes be injected to treat severe localized lesions.