Atopic dermatitis (AD) is a common, chronic inflammatory skin condition affecting up to 20% of children and 3% of adults worldwide. There is wide variation in the prevalence of AD among different countries. Although the frequency of AD is increasing in developing countries, it seems to have stabilized in developed countries, affecting approximately 1 in 5 schoolchildren. Adult-onset AD is not uncommon and is significantly higher, affecting between 11% and 13% of adults in some countries, for example, Singapore, Malaysia, and Sweden. AD is thus associated with significant health care economic burden in all age groups.