Baseline water loss and sweat gland response in acne patients during treatment with isotretinoin.

Eleven acne patients were treated with isotretinoin for 3-7 months. The water barrier function and the response of sweat glands to dilute methacholine injections were examined on upper back skin at onset and at several visits during therapy. Bilaterally located test sites representing healthy skin or skin sites which were least affected by acne lesions were selected for the study. The same sites were used at each visit for assessing the parameters. Although skin dryness was a common finding on the face and arms, no significant changes in baseline water loss (BWL) rates were found on the back skin during isotretinoin treatment. Instead there was a significant increase in the sweat gland responsiveness to methacholine during isotretinoin treatment as measured by the evaporimetric technique. Furthermore, in four out of five patients the numbers of active sweat glands, counted in plastic imprints from the stimulated test sites, showed a similar increase during therapy when compared to pretreatment values.