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Basics of UV Phototherapy

The healing effect of sunlight on inflammatory skin diseases has been known since ancient times. This applies in particular to psoriasis in conjunction with brine-containing bath applications. Individual, non-visible UV spectral ranges of sunlight (UV-A and UV-B) are responsible for the healing effect. However, excessive exposure to UV-A and UV-B can lead to sunburn and other acute side effects. Excessive long-term UV exposure also promotes skin aging and possibly the risk of skin cancer. For successful and safe UV phototherapy, in addition to the UV spectrum, the correct dosage is crucial.

UV-B 311nm narrow band spectrum

In the search for a particularly effective UV spectrum with few side effects, countless clinical studies have been conducted over the past 30 years. In the meantime, the UV-B (311nm) narrowband spectrum has proven to be particularly beneficial for a variety of skin diseases such as the treatment of psoriasis, neurodermatitis and vitiligo. In national and international medical guidelines, the UV-B (311nm) narrowband spectrum is preferred over other UV spectra due to efficacy, a low risk profile, ease of use, and availability.

UV Dosing

The most effective and at the same time tolerable dosage of UV radiation is measured by the so-called erythema threshold. This shows up like a mild sunburn in the form of a slight and rapidly fading reddening of the skin after treatment. Depending on the skin type, a therapy series always begins with a relatively low UV dose, which is then increased from session to session until the erythema threshold is reached.

In the course of treatment, the skin reacts with increasing pigmentation (tanning) and the formation of a light callus. These skin changes lead to an increase in the erythema threshold and allow the UV dose to be increased in the course of a treatment seri

UV Irradiation devices

UV irradiation is performed with full body cabins, partial body units or small hand-held devices. On one hand, the device should be as large as necessary to cover all affected skin lesions. On the other hand, the device should be as small as possible to protect unaffected skin areas from UV irradiation.

Large UV irradiation devices are costly in terms of equipment and are mainly found in clinics, medical practices and outpatient facilities. Smaller and especially hand-held devices can also be used in the home environment and save the user a lot of effort during the course of treatment. Smaller devices can also be used to treat larger individual lesions by treating the areas step by st

UV Monotherapy or combination therapy

UV phototherapy can be performed as monotherapy or as combination therapy. The aim of combination therapy is a strengthening effect of UV phototherapy and a faster treatment success. In balneophototherapy, phototherapy is combined with brine baths. PUVA treatment uses photosensitizing substances that are administered either systemically (oral medication) or topically (as a bath or cream). In addition to these two classic combination therapies, there are many other variants with different classic drugs and newer biologics.

An enhancing effect of the combination therapies is usually accompanied by increased risks and side effects. Furthermore, there may be unintended interactions between the procedures. Combination therapy should therefore always be carried out under strict medical supervisi

Residual risk of skin cancer

In principle, it can be assumed that excessive UV exposure can increase the risk of skin cancer. For many years, there were reservations against UV therapy for this reason. In the meantime, a number of retrospective studies are available on this issue. In a summary review from 2021, 5 cohort studies with about 230,000 patients were evaluated, with half treated with UV phototherapy and the other half serving as a control group. The review found no statistically detectable increased risk of skin cancer for the UV-B (311nm) narrowband spectrum. Even when taking a closer look at the skin type (different ethnic origin) or the cumulative therapy duration, no significantly increased risk could be determined.