Atopic dermatitis is very common. It usually starts in infants from 3-6 months and is generally a disease of small children but may occur for the first time at any age. It is closely associated with atopic diseases such as asthma, hay fever and food allergy. These atopic disorders run in families but inheritance is not predictable. IgE sensitisation is present in about 80% of patients with atopic dermatitis and may present in young children with food allergies or acute allergic urticaria due to relevant exposures, such as contact with latex or taking antibiotics. About 20-40% of patients with atopic dermatitis have a genetic mutation of the gene encoding filaggrin in the stratum corneum, which results in impaired barrier function of the skin. This may, in turn, promote sensitisation by facilitating absorption of allergens through the skin, leading to ongoing inflammation and allergic airways disease.