There are several types of dermatitis. These include:

Allergic contact dermatitis, which is caused by an allergic reaction or contact with an irritating material. It is difficult to determine what triggers this condition because most people will come into contact with many substances in the course of the day. A prime example of contact dermatitis is a person’s reaction to poison ivy, a plant that produces oils that cause itching and other conditions. The skin has to come into contact with the plant for only a moment to cause the condition. Many other plants, fruits, herbs, flowers and vegetables can cause similar reactions. But living things are not the only cause of contact dermatitis. Hair dyes, fragrances, rubber, metals, formaldehyde and skin care products also can trigger the skin irritations.

Another form of dermatitis is irritant contact dermatitis. In this, irritation is caused by a substance that repeatedly comes into contact with the skin. A classic example is washing hands repeatedly and damaging skin, which may dry out and crack.

Nummular dermatitis is seen when coin-shaped red sores appear on the legs, hands, arms and torso. Men get it more than women, and it usually appears in older people between ages 55 and 65. It can be caused by taking frequent hot showers or living in a dry environment.

Atopic dermatitis, also known as eczema, is a skin condition characterized by itchy, scaly, swelling and sometimes blistering skin. This is a genetic condition that is usually passed down through families. It is associated with asthma, allergies and particularly stress. Researchers believe that skin barrier defects that let in moisture and germs may be responsible for the condition.