The cause of atopic dermatitis isn't clear, but it affects your skin's ability to hold moisture. Your skin becomes dry, itchy, and easily irritated.
Most people who have atopic dermatitis have a personal or family history of allergies, such as hay fever (allergic rhinitis) or asthma.
Things that may make atopic dermatitis worse include:
- Allergens, such as dust mites or animal dander.
- Harsh soaps or detergents.
- Weather changes, especially dry and cold.
- An allergic reaction to certain foods, such as eggs, peanuts, milk, wheat, fish, or soy products.
- Skin infection.
Atopic dermatitis starts with dry skin that is often very itchy. Scratching causes the dry skin to become red and irritated (inflamed). Infection often occurs. Tiny bumps that look like little blisters may appear and ooze fluid or crust over. These symptoms-dryness, itchiness, scratching, and inflammation-may come and go. Over time, a recurring rash can lead to tough and thickened skin.
Mild atopic dermatitis affects a small area of skin, isn't very itchy, and usually goes away with moisturizer. Severe atopic dermatitis covers a large area of skin that is very itchy and doesn't go away with moisturizer.
People tend to get the rash on certain parts of the body, depending on their age. Common sites for babies include the scalp and face (especially on the cheeks), the front of the knees, and the back of the elbows. In children, common areas include the neck, wrists, legs, ankles, the creases of elbows or knees, and between the buttocks. In adults, the rash often appears in the creases of the elbows or knees and on the nape of the neck.
A doctor can usually tell if you have atopic dermatitis by doing a physical exam and asking questions about your past health.
Your doctor may advise allergy testing to find the things that trigger the rash. Allergy tests can be done by an allergist (immunologist) or dermatologist.