Environmental factors independently associated with the first episode of wheezing among children.

30-yr-old patient who was treated with isotretinoin for 3 months (5). The third report describes the successful treatment of acne vulgaris in a 13-yr-old patient who was treated with isotretinoin for 5 months (6). In none of the reports, the authors provide information on the concentration of itraconazole in blood of their patients while on comedication with isotretinoin, so we suspect that the life-threatening suppression of itraconazole by isotretinoin in the previously reported patients was most likely simply not noticed by the treating physicians (4–6). So their recommendation to use isotretinoin in patients with CGD must be carefully revisited (4–6). We here highlight the need to at least closely monitor levels of itraconazole when given together with systemic isotretinoin, if not the necessity to refrain from isotretinoin for treatment of acne vulgaris if cotreatment with itraconazole is mandatory as in CGD. The increased metabolism of itraconazole by systemic isotretinoin leading to induction of cytochrome P450 is highlighted in the pharmaceutical information on isotretinoin and is probably well known to the dermatologist. However to our knowledge, our report for the first time explicitly shows that comedication of itraconazole with systemic isotretinoin may cause dangerously low levels of itraconazole in CGD. The potentially life-threatening suppression of itraconazole by isotretinoin must be considered when using isotretinoin for a common and non-life-threatening condition like acne vulgaris in patients with CGD.