There is an emergent evidence demonstrating the role of Vitamin D deficiency in eczema. Vitamin D supplementation with standard treatment yielded positive clinical outcomes for children and adolescents with mild and moderate AD; however, the potential benefit of vitamin D in severe cases remains unclear

Inclusion Criteria:

1.diagnosis of severe AD according to Hanifin and Rajka criteria and the Eczema Area and Severity Index (EASI) score

Exclusion Criteria:

1. serious skin disorder other than AD.
2. taking systemic corticosteroids or anti-inflammatory medications, prior vitamin D supplementation
3. receiving oral or topical antibiotics or topical calcineurin inhibitors for at least one week prior to enrollment
4. known gut absorption problem, presence of active skin infection at baseline any known hepatic and/or renal disease.