Phototherapy is a treatment of affected skin with ultraviolet (UV) rays. It has an anti-inflammatory effect and inhibits the accelerated rate of skin cell reproduction and maturing.
Narrow-band UVB therapy with rays having the wavelength of 311nm are most used to treat psoriasis. When psoriasis is more severe, UVA radiation in combination with a photosensitizer (psoralen), which is called photochemotherapy or PUVA (Psoralen + PUVA), is used. The photosensitizer can be taken by the patient in the form of tablets or capsules or applied to the skin with an ointment or in a bath. It usually requires the patient to undergo between 20 and 30 irradiations to achieve remission, which are performed in special therapy centers.
UV radiation is carcinogenic and increases the risk of developing skin cancer. The number of radiation treatments is limited to 300 photochemotherapies overall.
Patients with psoriasis are advised against sun or solarium exposure as they have carcinogenic properties.
- Pathirana D, et al. J Eur Acad Dermatol Venereol 2009; Oct;23 Suppl 2:1-70.
- Nast A, et al. J Eur Acad Dermatol Venereol 2015; 29:2277-94.
- Hsu S, et al. Arch Dermatol 2012; 148:95-102.
- National Psoriasis Foundation website: https://www.psoriasis.org/biologics/ Accessed March 2021.
- Psoriasis Association SA Webpage: https://psoriasis.org.za/types-treatments/ Accessed March 2021.
- National Psoriasis Foundation Website: https://www.psoriasis.org/treatments-for-psoriatic-disease/ Accessed March 2021.
Recensed by assist. Katarina Trčko, MD, PhD; Department of Dermatology and Venereal Diseases, University Medical Centre Maribor