Participants must have been diagnosed with moderate to severe atopic dermatitis (eczema) for at least 12 months (if 6 years old or older) or at least 6 months (if 2 up to 6 years old)

Participants must not have had satisfactory results with existing medications applied to the skin within 6 months before screening

Participants must be willing to stop taking certain eczema treatments

Participants must agree to use a lotion or cream that softens the skin daily

Participants must not have other skin conditions (such as psoriasis or lupus) or a history of skin diseases or infections that did not respond to treatment or require frequent hospitalization and/or IV treatment

Participants must not have a skin infection that requires antibiotics

Participants must not have been treated with corticosteroids given by injection within 6 weeks prior to treatment assignment and are not expected to need corticosteroid injections during the study

Participants must not have uncontrolled high blood pressure, major surgery (within the last two months or planned to take place during the study), or recent blood clot, heart attack, chest pain, stroke, heart failure or any other serious or unstable disease or infection

Female participants must not be pregnant or breastfeeding