UVB phototherapy refers to irradiation of the skin with short wave ultraviolet radiation. To treat the whole body, the patient, undressed, stands in a specially designed cabinet containing fluorescent light tubes.
Increasing doses of UVB are given each exposure (three times weekly), aiming to turn the skin slightly pink.
Psoriasis is a common inherited skin disorder, which may vary considerably in extent and severity. Neither phototherapy nor any other available treatment effects a permanent cure.
UVB is suitable for most people with extensive psoriasis. It may not suit those with very fair skin, or those whose psoriasis gets worse in sunlight.
Initially most patients have their treatment three times a week. The first few exposures will be short (less than 5 minutes). The length of exposure is gradually increased, according to the patient's response.
Most psoriasis patients will have their psoriasis cleared or much improved after 12 to 24 treatments. At this stage treatments will usually be discontinued. Even without treatment, the skin may remain clear for some months. However, the psoriasis may later flare up again, and further UVB treatment may be necessary.
Those cases of psoriasis which appear to be resistant to phototherapy may respond to other treatments (e.g. ointments or tablets).
UVB is occasionally used for severe cases of dermatitis, especially atopic eczema. Frequency and dosage of treatment is similar to that used for psoriasis. However, a course of phototherapy may need to be more prolonged than that generally required for psoriasis.
UVB is one of the most effective treatments for vitiligo. Treatments must be cautious as the white skin burns easily. It may take several months to see an improvement.
Many other skin conditions have been effectively treated with UVB, including generalised itch, prurigo, cutaneous T-cell lymphoma, pityriasis lichenoides, and symptomatic dermographism.