Dermatitis is a blanket term meaning any "inflammation of the skin" (e.g. rashes, etc.). There are several different types of dermatitis. The different kinds usually have in common an allergic reaction to specific allergens. The term may be used to refer to eczema, which is also known as dermatitis eczema or eczematous dermatitis. A diagnosis of eczema often implies childhood or atopic dermatitis, but without proper context, it means nothing more than a "rash".

Spongiotic dermatitis

This pattern of skin reaction includes many other subtypes - irritant dermatitis, seborrheic dermatitis, atopic dermatitis, allergic contact dermatitis, thermal induced dermatitis, and drug induced dermatitis.

Childhood eczema

Also known as atopic dermatitis, or atopic eczema. This can be immunologic mediated dermatitis. In dogs, it is frequently associated with airborn allergen or food allergen. In humans, it can be associated with food allergy. However, most cases of human atopic dermatitis does not have an associated allergy. It is believed that the human skin is lacking in a protective lipid agent, making the skin itchy and prone to scratching.

Allergic contact dermatitis

Contact dermatitis can be due to external compounds, preservatives, fragrances, or plants. A classical case is poison ivy dermatitis (Rhus dermatitis). Patch testing can be performed with a number of allergen (example, the TRUE TEST patch test, which has 29 allergens).

Seborrhoeic dermatitis

Seborrhoeic dermatitis is also known as dandruff. A rash of the scalp, face, and occasionally chest and groin. It is associated with a common yeast, Pityrosporum. It is treated with either an antiinflammatory or an antifungal agent, or both.

Psoriasis

Psoriasis or psoriatic dermatitis is a pattern of dermatitis with distinct relationship to a defined entity, psoriasis. It can be familial, and is associated with arthritis.

Dyshidrotic dermatitis

Dyshidrotic dermatitis is also known as Pompholyx. It is a pattern of spongiotic dermatitis presenting as small fluid filled or pus filled bumps on the hands and feet. The cause is unknown, but it has been highly associated with contact dermatitis (see Allergic Contact Dermatitis). Some cases are due to a food intolerance to nickel.

Urticaria

Urticaria is also known as hives and is a pattern of allergic dermatitis characterized by transient wheals or welts. The definition require that the lesions shifts, moves, or changes within 24 hours. They should not remain static, or the diagnosis of urticaria can not be rendered.

Vesicular or bullous dermatitis

This can be caused by drug reaction, or auto immune diseases. Examples includes Steven Johnson Syndrome, bullous erythema multiforme, bullous pemphigoid, and pemphigus vulgaris. Athlete foot fungus can also cause bullous dermatitis of the foot.

Papular urticaria