Dermatitis is when the skin becomes red, swollen, and sore, sometimes with small blisters, resulting from direct irritation of the skin by an external agent or an allergic reaction to it.

Each type of dermatitis may look a little different and tends to occur on different parts of your body. The most common types of dermatitis include:

Atopic dermatitis or eczema is a red, itchy rash that usually begins in infancy on a baby’s scalp and/or cheeks. As the child ages and into adulthood, the rash most commonly occurs where the skin flexes (like inside the elbows, behind the knees and the front of the neck.) When scratched, the rash can leak fluid and crust over. While the cause of eczema is not known, this form of dermatitis can be related to a mix of factors, including: certain foods, dry skin, a gene variation, an immune system dysfunction, bacteria on the skin and environmental conditions. People with atopic dermatitis may experience improvement and then flare-ups.

Contact dermatitis occurs on areas of the body that have come into contact with substances that either irritate the skin or cause an allergic reaction, such as poison ivy, fabrics, jewelry containing nickel, preservatives, soaps or essential oils in fragrance. The red rash may burn, sting, itch or form blisters.

Seborrheic dermatitis causes scaly patches, red skin and stubborn dandruff. It usually affects the more oily areas of the body such as the face, scalp (cradle cap in infants), upper chest and back. Seborrheic dermatitis can be a long-term condition with periods of improvement and flare-ups.