Eczema is not a single health condition but a recognizable reaction pattern seen in a number of skin diseases. Atopic dermatitis, a common cause of eczema, is more prevalent in those with asthma and hay fever. Eczema signs and symptoms include tiny blisters (vesicles) that can weep and ooze, eventually producing crusted, thickened plaques of skin. It is almost always quite itchy. It is important to distinguish the different causes of eczema because effective treatments often differ.