Topical Treatment

Many patients respond very well to treatments applied directly to the skin. Topical treatments include:

• Corticosteroid creams and ointments (most common treatment)
• Synthetic forms of vitamin D and retinoids (calcipotriene ointment)
• Retinoids (tazarotene gel 0.05 and 0.1%)
• Coal tar preparations (Denorex, Pentrax, Tegrin, Zetar)
• Bath solutions and moisturizers
• Tacrolimus and pimecrolimus (especially for inverse psoriasis)

Photo (Light) Therapy

If psoriasis covers more than 30% of the body, it is difficult to treat with topical medications alone. Daily, short, nonburning exposure to sunlight clears or improves psoriasis in many people. Sunlight is often included among initial treatments. A more controlled form of artificial light treatment (UVB phototherapy) is often used in cases that are more widespread. Alternatively, psoriasis can be treated with ultraviolet A (UVA light) and psoralen. Psoralen is an oral or topical medication that makes the body more sensitive to light. This treatment is known as PUVA.

Phototherapy can be very effective in controlling psoriasis but it requires frequent treatments. It may cause side effects such as nausea, headache, and fatigue, burning, and itching. Both UVB and PUVA may increase the person's risk for squamous cell and, possibly, melanoma skin cancers. It is unclear whether UVB increases the risk of skin cancer.

Systemic Treatment

For more severe types of psoriasis, doctors may prescribe a number of other powerful medications, which can be effective, but are associated with side effects that are more serious. These include:

• Methotrexate (Rheumatrex, Trexall)—a type of systemic medicine that affects the whole immune system; should not be taken by pregnant women, women planning to become pregnant, or by their male partners
• Cyclosporine (Gengraf, Neoral)—another type of systemic medicine that suppresses the immune system to slow the turnover of skin cells; should not be taken by pregnant or breastfeeding women
• Hydroxyurea (Hydrea)—less toxic than methotrexate or cyclosporine, but may be less effective
• Systemic retinoids—Compounds with vitamin A-like properties taken internally may be prescribed in severe cases. Retinoids can cause birth defects, and women must diligently protect themselves from pregnancy for several years after completing treatment. Systemic retinoids are often combined with phototherapy for increased effectiveness and for their property of being protective against squamous skin cancer.

Newer medicines include biologic agents, which affect a part of the body's immune response. For example, ustekinumab (Stelara) is a recently approved drug that targets certain cells in the immune system that cause inflammation.