Contact Dermatitis.

Contact dermatitis is skin inflammation caused by direct contact with a particular substance. The rash is very itchy, is confined to a specific area, and often has clearly defined boundaries.

Contact Dermatitis

Substances can cause skin inflammation by one of two mechanisms—irritation (irritant contact dermatitis) or allergic reaction (allergic contact dermatitis).

Irritant contact dermatitis, which accounts for 80% of all cases of contact dermatitis, occurs when a chemical substance causes direct damage to the skin; symptoms are more painful than itchy. Typical irritating substances are acids, alkalis (such as drain cleaners), solvents (such as acetone in nail polish remover), strong soaps, and plants (such as poinsettias and peppers). Some of these chemicals cause skin changes within a few minutes, whereas others require longer exposure. People vary in the sensitivity of their skin to irritants. Even very mild soaps and detergents may irritate the skin of some people after frequent or prolonged contact.

Allergic contact dermatitis is a reaction by the body's immune system to a substance contacting the skin. Sometimes a person can be sensitized by only one exposure, and other times sensitization occurs only after many exposures to a substance. After a person is sensitized, the next exposure causes itching and dermatitis within 4 to 24 hours, although some people, particularly older people, do not develop a reaction for 3 to 4 days.

Thousands of substances can result in allergic contact dermatitis. The most common include substances found in plants such as poison ivy, rubber (latex), antibiotics, fragrances, preservatives, and some metals (such as nickel and cobalt). About 10% of women are allergic to nickel, a common component of jewelry. People may use (or be exposed to) substances for years without a problem, then suddenly develop an allergic reaction. Even ointments, creams, and lotions used to treat dermatitis can cause such a reaction. People may also develop dermatitis from many of the materials they touch while at work (occupational dermatitis).

Sometimes contact dermatitis results only after a person touches certain substances and then exposes the skin to sunlight (photoallergic or phototoxic contact dermatitis). Such substances include sunscreens, aftershave lotions, certain perfumes, antibiotics.

Seborrhoeic dermatitis.

It should be differentiated with Seborrhoeic dermatitis, Irritant or allergic eczematous contact dermatitis, Scabies , Psoriasis (Palmo plantar), Dermatitis Herpetiformis .
While managing a case one should take care that any external irritation - sudden change of temperature, excessive bathing ,vigorous rubbing, insufficient cleanliness especially in diaper region, local infections, irritating secretions or even medicated oils are to be avoided. Attacks may be induced by teething also. One of the first consideration is prevention from scratching the parts affected and mechanical restraints may be resorted to as cardboard splints over elbow to prevent the child's hands from reaching his face. As soap and water may aggravate the disease olive oil on absorbant cotton may be used for cleansing. Particular attention should be given to genitals, and buttocks, diapers should be changed whenever soiled. Parts cleaned with vegetable or mineral oil and powdered with corn starch .In cases where specific food allergies are implicated dietary restrictions are in order. The food substitutes for wheat are oat, rice (puffed rice, boiled rice) , when milk is eliminated souyabean emulsion gives adequate nourishment.