A Study to Evaluate Upadacitinib in Combination With Topical Corticosteroids in Adolescent and Adult Participants With Moderate to Severe Atopic Dermatitis

* Body weight of ≥ 40 kg at Baseline Visit for participants ≥ 12 and \< 18 years of age * Chronic atopic dermatitis (AD) with onset of symptoms at least 3 years prior to Baseline Visit and subject meets Hanifin and Rajka criteria. * Active moderate to severe atopic dermatitis defined by Eczema Area and Severity Index (EASI) ≥ 16, validated Investigator's Global Assessment (vIGA) ≥ 3, ≥ 10% of body surface area (BSA) with AD involvement, and weekly average of daily Worst Pruritus numerical rating scale (NRS) ≥ 4. * Subject has applied a topical emollient (moisturizer) twice daily for at least 7 days before the Baseline Visit. * Documented history of inadequate response to topical corticosteroids or topical calcineurin inhibitor OR documented systemic treatment for AD within 6 months prior to Baseline Visit

* Prior exposure to any Janus kinase (JAK) inhibitor * Unable or unwilling to discontinue current atopic dermatitis (AD) treatments prior to the study * Requirement of prohibited medications during the study * Other active skin diseases or skin infections requiring systemic treatment or would interfere with appropriate assessment of atopic dermatitis lesions * Female subject who is pregnant, breastfeeding, or considering pregnancy during the study