Ultraviolet light and psoriasis

Ultraviolet B (UVB)

UVB light is more effective than UVA light for treating psoriasis.

  • Exposure times start at 30 to 60 seconds and are gradually increased until light causes the skin to turn red. When the skin no longer turns red after this much exposure, the time is increased.
  • Treatments are given daily or several times a week.
  • UVB light is used alone, with tar products (Goeckerman treatment), or with anthralin applied to the skin (Ingram regimen).

Ultraviolet A (UVA)

UVA penetrates deeper into the skin than UVB.

  • Treatment with UVA typically takes 20 minutes per session.
  • UVA light used with psoralen drugs is called PUVA. With PUVA, the treatment time is greatly reduced, from 20 minutes to about 2 minutes.


Author: Maria G. Essig, MS, ELSLast Updated: December 10, 2007
Medical Review: Kathleen Romito, MD - Family Medicine
Alexander H. Murray, MD, FRCPC - Dermatology

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