Phototherapy

Phototherapy has an immunosuppressive action on the skin and has a particular effect on blocking antigen-presenting Langerhans cells, altering eosinophil functions and altering production of cytokines by keratinocytes (Hoare et al., 2000).

Narrowband UVB (TL01) is the most common form of phototherapy used to treat skin diseases. Narrowband refers to a specific wavelength of ultraviolet (UV) radiation, 311– 312 nm. PUVA or photochemotherapy is used for more severe eczema and involves a combination treatment that consists of psoralens (P) and then exposing the skin to UVA (long-wave ultraviolet radiation). Psoralens are compounds found in many plants which make the skin temporarily sensitive to UVA. Medicinal psoralens include methoxsalen (8-methoxypsoralen), 5- methoxypsoralen and trisoralen. Eye protection is required; 24 hours post-oral administration of psoralens. Psoralens can also be applied topically in a bath soak or as lotion for small areas (hands and feet). The amount of UV is carefully monitored for side effects and especially degrees of erythema and burning. A number of protocols exist depending on the individual’s skin type, age, skin condition and other factors. Patients will generally attend hospital 2–3 times a week for stepped administration of phototherapy (Hoare et al., 2000).