There are several different types of eczema, which have different symptoms and triggers.
Atopic eczema is the most common of the many types of eczema, and is characterised by itchy, inflamed skin. Atopic eczema is believed to be caused by an abnormal function of the body's immune system. The condition tends to come and go, depending upon exposure to triggers or causative factors. When atopic eczema starts in infancy it is sometimes termed infantile eczema. Atopic eczema tends to run in families, and people who develop the condition often have a family history of allergic conditions such as asthma or hayfever.
Contact eczema ( contact dermatitis) is a localised reaction that includes redness, itching, and burning where the skin has come into contact with an allergen (an allergy-causing substance) or with an irritant such as an acid, a cleaning agent, or other chemical. Other examples of contact eczema include reactions to washing powder and liquids, nickel (present in jewellery and clothing buckles), cosmetics, fabrics, clothing, and perfume. The condition is sometimes referred to as allergic contact eczema (allergic contact dermatitis) or irritant contact eczema (irritant contact dermatitis) depending on what is involved in triggering the reaction. Skin reactions to certain plants such as primulas and chrysanthemums are examples of allergic contact eczema. People who have a history of allergies have an increased risk of developing contact eczema.
Seborrhoeic eczema ( seborrhoeic dermatitis) is a form of skin inflammation of unknown cause. The signs and symptoms of seborrhoeic eczema include yellowish, oily, scaly patches of skin on the scalp, face, and occasionally other parts of the body. Dandruff and " cradle cap" in infants are examples of seborrhoeic eczema. Seborrhoeic eczema is not necessarily associated with itching. This condition tends to run in families. Emotional stress, oily skin, infrequent shampooing, and weather conditions may all increase a person's risk of developing seborrhoeic eczema.
Nummular or discoid eczema
Nummular eczema (nummular dermatitis) is characterised by coin-shaped patches of irritated skin, most commonly located on the arms, back, buttocks, and lower legs, that may be crusted, scaling, and extremely itchy.
This form of eczema is relatively uncommon and occurs most frequently in elderly men. Nummular eczema is usually a chronic condition. A personal or family history of atopic eczema, asthma, or allergies increases the risk of developing the condition.
Neurodermatitis, also known as lichen simplex chronicus, is a chronic skin inflammation caused by a scratch-itch cycle that begins with a localised itch (such as an insect bite) that becomes intensely irritated when scratched. Women are more commonly affected by neurodermatitis than men, and the condition is most frequent in people aged between 20 and 50. This form of eczema results in scaly patches of skin on the head, lower legs, wrists, or forearms. Over time, the skin can become thickened and leathery. Stress can worsen the symptoms of neurodermatitis.