Determination of the minimal erythema dose for ultraviolet A1 radiation

Abstract

Most participants had no measurable UVA1-MED even after commencing high doses such as 130 J cm . Only a minority of participants (14%) may develop UVA1-induced erythema in the low- and medium-dose region. Hence, it appears to be safe to start UVA1 phototherapy with 20 J cm of UVA1 and continue with subsequent daily dose increments of 10 J cm , up to the desired maximum dose.

Ultraviolet A1 Phototherapy for Fibrosing Conditions

“…If this proves not to be the case then a fixed start dose, for example, 20 J/cm 2 would usually be a safe approach, but there would then be the concern of potential under-treatment if running at doses that are well below the erythemal threshold (18, 19). UV-A1-MED data of two recent studies indicate that 20 J/cm 2 do usually not lead to erythema (20–22).…”

Systematic review of the efficacies and adverse effects of treatments for pityriasis lichenoides

“…15 Using the minimal erythemal dose to calculate the initial dose may help minimize the risk of this side-effect. 42 Only two RCTs were found. 18,19 In one study (n = 30), PUVA had the highest rate of remission compared with topical CTS or topical CTS with tetracycline.…”

A practical approach to the initial dose and subsequent increments for ultraviolet A1 phototherapy

“…The paper by Gambichler et al . shows that although 33 patients (56%) did not develop any erythematous reaction 24 h after high UVA1 doses (like 130 J cm −2 ), 18 (30%) and eight patients (14%) had a UVA1 minimal erythema dose within the therapeutic high‐ and medium‐dose region, respectively . As a result of their findings, the authors suggest a regimen with a fixed 20 J cm −2 initial dose, followed by subsequent step‐wise dose increments of 10 J cm −2 per session, until reaching the planned maximal dose, which is then maintained.…”

“…In this issue of the BJD , Gambichler et al . present their interesting findings on the characteristics of ultraviolet (UV)A1‐induced erythema of healthy skin, and they propose a much‐needed practical approach to the initial dose and subsequent dose increments of UVA1 phototherapy …”

“…Although it is still unknown, after > 30 years, whether UVA1 phototherapy has such risks or not, it seems advisable to prefer fixed ‘medium’ rather than ‘high’ doses to limit the cumulative UVA1 exposure, along with using, at first exposures, the regimen suggested by Gambichler et al . to help avoiding episodes of sunburn …”