Emollient use and effects on cutaneous allergen reactions: a preliminary study

Abstract Recently, there has been some evidence of an increased incidence of food allergy in infants regularly applying some types of emollients. Considering that emollient vehicles can modify the delivery of ‘actives’ into the skin, it is important to examine their effects on epicutaneous sensitization to environmental allergens. The aim was to determine the effects of regular emollient use on cutaneous reactions to house dust mite allergen. An observer-blind within-participant multilateral controlled interventional study in 40 adults with confirmed house dust mite allergy was carried out. Participants underwent 4 weeks of treatment with olive oil, coconut oil and a basic emollient cream (no added moisturizers) applied to three different areas of both forearms with a fourth area left as a no-treatment control (NTC). At the end of treatment, skin barrier integrity was assessed by performing transepidermal water loss (TEWL) measurements in conjunction with tape-stripping. At adjacent locations, atopy patch tests (APTs) using house dust mite allergen were performed. This interim analysis includes data from the first 16 participants. Skin barrier integrity was reduced by all three treatments relative to NTC as indicated by elevated TEWL [mean (SD) olive oil 35.10 (15.17), coconut oil 36.56 (17.17) and emollient cream 39.18 (20.91) vs. NTC 28.76 (13.06) g m–2 h–1; P < 0.05]. Pretreatment of the skin had a significant effect on APT reactions (P = 0.0401, graded from 0 to 4). The strongest reactions were seen following pretreatment with emollient cream [2.31 (1.12)], olive oil [2.22 (0.91)] and coconut oil [1.94 (0.91)] vs. NTC [1.50 (0.80)]. These preliminary results suggest that some commonly used emollients decrease skin barrier integrity and increase the severity of reactions to house dust mite allergens. This implies that regular use of emollients that damage the skin may directly affect allergy development arising from epicutaneous sensitization. Some sophisticated emollients (with moisturizers) have been shown to improve skin barrier function. Clinical trials are therefore needed to determine if they impart protection against epicutaneous sensitization.