A Study to Learn About the Study Medicine Abrocitinib in People With Severe Atopic Dermatitis Who Have Switched From Other Therapies

The purpose of this observational study is to learn about the effects of the study medicine (called abrocitinib) for the treatment of severe atopic dermatitis in people that were moved from previous novel therapies, known as "advanced" therapies. Atopic dermatitis is a long-lasting skin condition that causes the skin to become inflamed, dry, and itchy. This study is seeking participants who: * are 18 years of age or older; * have severe atopic dermatitis; * have previously been treated with advanced therapies authorised for atopic dermatitis and are moving to abrocitinib (100 mg or 200 mg); * have received no more than two authorised advanced therapies for their atopic dermatitis. All participants will receive study medicine, abrocitinib as part of their usual medical care. The decision to give the study medicine is made by their dermatologist. This decision is independent of participation in the study. Abrocitinib will be taken by mouth at home once daily as prescribed by the treating doctor. We will examine the experiences of people receiving abrocitinib for up to one year after starting abrocitinib. We will look back at the information up to 6 months before they have started taking abrocitinib. This will help us learn how abrocitinib affects severe atopic dermatitis in people who have moved from other authorised advanced therapies. Participants will take part in this study for 1 year. During this time, they will have about 5 visits. These visits are a part of their routine care. During the visits, the doctor will assess how severe atopic dermatitis is. Participants may be asked questions about their symptoms and how the condition affects their daily life. No additional clinic visits, tests, or procedures are required for this study, beyond normal clinical practice.