What is dermatitis?

Dermatitis (inflammation of the skin), is a common problem which affects most people at some time. It usually results in red, swollen or blistered, intensely itchy areas of skin.

Some people with an allergic tendency, often inherited, will suffer from the chronic form of dermatitis known as eczema. This is sometimes referred to as "endogenous" (meaning from within) dermatitis.

But many others will experience a form of dermatitis called "exogenous", (or "contact") dermatitis. Exogenous means due to external factors. Contact dermatitis is the result of direct contact with a variety of substances.

Types of contact dermatitis:

There are two types of contact dermatitis: irritant and allergic.

Irritant contact dermatitis

"Irritant" contact dermatitis is produced by the direct chemical effect of certain substances on the skin. The severity of the dermatitis will depend on how long the substance is in contact with the skin and the concentration of the offending material.

Common causes of irritant contact dermatitis include detergents and solvents, acids, alkalis, oils and skin cleansers.

Certain occupations are more prone to this form of dermatitis. These include:

Allergic contact dermatitis

The "allergic" form of contact dermatitis is less common, affecting a small number of people who, for some reason, become sensitive to certain common everyday substances. They may have been in contact with these materials for years before the sensitivity develops.

The most common cause of allergic contact dermatitis, usually affecting women, is nickel. This is found in many metal objects worn next, or close, to the skin. Costume jewellery, metal studs on jeans or sleepers in pierced ears are usually to blame.

Other allergens (things causing allergy) are chromates (especially in cement), rubber and some creams and ointments used for medical purposes.

What to do when you have contact dermatitis

When contact dermatitis is suspected, the obvious first step is to try to find the cause. With an irritant cause this is usually easy, especially as the skin problem is often confined to those areas actually in direct contact with the irritant.

With an allergic cause the rash may be more widespread, making identification of the cause harder. If the rash is less obvious at weekends or during holidays, it is probably due to a work-related substance.

A streaky rash is often due to an allergy to a plant which the affected person has brushed past. Primula, Rhus tree and chrysanthemum are examples of plants which can cause problems.

Sometimes patch testing, in which a number of suspected materials are applied to separate areas of skin for up to 48 hours, will solve the mystery.

Treatment of contact dermatitis usually means the use of corticosteroid creams or ointments.

Whenever possible, contact with the cause of the dermatitis must stop. This might mean abandoning a favourite piece of jewellery, or taking meticulous care always to wear protective gloves when doing housework.