Different skin allergies may affect children and adults differently. Many skin allergy conditions develop during early childhood, and symptoms usually improve or go away completely by adulthood. One such condition is atopic dermatitis, which is a skin disorder that may be triggered by allergies and is quite common in children but usually disappears by the age of 25. Other skin allergies are more common in adults or can last a lifetime. For example, allergic contact dermatitis, which happens when a substance that touches the skin triggers an allergic reaction, is more common in adults.