Atopic dermatitis, also known as eczema, is a condition that causes skin inflammation and makes the skin itchy and dry. It's most common in people who have asthma, hay fever, or food allergies, but anyone can get it. Symptoms of atopic dermatitis usually appear before age 5 and can vary from mild to severe. In severe cases, it can also lead to skin lesions, infection, and even hair loss.