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UVB phototherapy refers to irradiation with short wave ultraviolet radiation. To treat the whole body, the patient, undressed, stands in a specially designed cabinet containing fluorescent light tubes.
Traditionally, broadband UVB has been used, but increasingly, narrowband UVB phototherapy (311nm) is provided.
Increasing doses of UVB are given each exposure (three to five times weekly), aiming to turn the skin slightly pink. Sometimes uncomfortable sunburn will occur, at its worst about 8 hours after treatment. This fades over the next few days and should be treated with frequent and liberal emollients.
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, up to a maximum of 30 minutes per session. Few patients require such long exposures, most being controlled with shorter times.
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 UVB may still be helped by another form of ultraviolet treatment called PUVA, or 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.
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