Systemic Therapy for Psoriasis

Melvin Lee, MD; Robert E. Kalb, MD


Dermatology Nursing. 2008;20(2):105-111. 

In This Article

Ultraviolet B (UVB) Phototherapy

In UVB phototherapy, the skin is exposed to ultraviolet light in the UVB wavelengths (290-320 nm). Patients can receive this treatment in the office or at home, with ultraviolet light bulbs mounted in a booth or in a panel. Typically, patients are treated three times a week, starting with a dose according to their skin type or calculated minimal erythema dose. There are regular dosage increases each session up to the patient's maximum target dose (Zanolli & Feldman, 2005). Patients continue treatments with further increases or decreases in dose as tolerated until their psoriasis is cleared. Treatment frequencies and dosing then can usually be tapered to maintain clearance (Boztepe, Karaduman, Sahin, Hayran, & Kolemen, 2006).

More recently, the UVB spectrum was examined in detail and a narrow range of wavelengths (311-312 nm) was found the most effective (Diffey & Farr, 1987; Parrish & Jaenicke, 1981). Phototherapy using this narrower range of wave lengths is called narrow-band UVB (NB-UVB), and the older form of phototherapy using the full UVB spectrum is called broad-band UVB (BB-UVB). NB-UVB clears lesions faster than BB-UVB, and as a result, fewer treatments are needed (Coven et al., 1997).

UVB phototherapy, one of the oldest known treatments for psoriasis, enjoys a long record of safety. Over decades of use, no studies have convincingly shown an increased risk of skin cancer with BB-UVB (Lee, Koo, & Berger, 2005; Stern & Laird, 1994). However, similar data for NB-UVB is still not yet available. Short-term side effects of both BB-UVB and NB-UVB include phototoxicity and photosensitivity reactions. These reactions are less likely to occur with NB-UVB but peak later and last longer (Coven et al., 1997). Phototoxicity within psoriatic lesions is also more common in NB-UVB (Calzavara-Pinton, Zane, Candiago, & Facchetti, 2000; George & Ferguson 1992). A logistical concern with all forms of phototherapy is the time and expense required for multiple treatments per week (including insurance co-payments).


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