Contact dermatitis
Contact dermatitis
What is contact dermatitis?
Dermatitis (also known as eczema) describes a type of inflammation of the skin. Contact dermatitis (contact eczema) is a term used when this inflammation is caused by direct or indirect skin contact with something in a person’s environment.
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What causes contact dermatitis?
- Irritant contact dermatitis develops when the skin is in contact with irritating substances like detergents, solvents and hot water. These strip the skin of its natural oils. Dermatitis develops when there is repeated and regular or prolonged contact with such irritating substances. The most important factors in causing this type of contact dermatitis are the frequency of exposure and, for detergents and solvents, the concentration. It is very common in people who have their hands in water a lot, such as nurses, hairdressers, bartenders, cooks and cleaners, leading to hand dermatitis. Anyone can develop an irritant contact hand dermatitis from handling irritating substances, or with frequent handwashing. It is, however, more likely in people who have suffered from types of dermatitis in the past, such as childhood eczema.
- Allergic contact dermatitis occurs when allergy develops to a specific chemical or substance that has been in contact with the skin. Examples of these substances include hair dye, nail cosmetics, perfumes, metals such as nickel, rubber, and preservatives used in some cosmetics. It is not known why some people who are exposed to these allergens develop an immune reaction to them while others do not. It does not appear to be more likely in individuals who have had childhood eczema. Less commonly, proteins (for example in raw fruits and vegetables, such as uncooked potatoes), can cause an immediate allergic reaction on the hands when touched. This leads to itchy skin swellings known as contact urticaria (hives). It can trigger a flare of pre-existing hand dermatitis known as ‘protein contact dermatitis’, with the development of small blisters, redness, scaling and itching. Contact dermatitis is not infectious and cannot be caught from nor spread to other people.
Is contact dermatitis hereditary?
People with a tendency to asthma, eczema and hay fever develop irritant contact dermatitis more easily than others, and this tendency runs in families. Allergic contact dermatitis is not normally hereditary.
What are the symptoms of contact dermatitis?
Itching of the skin is the commonest symptom and can be intense. Sometimes the skin becomes sore and red; small and occasionally large blisters may develop and can weep. In contact dermatitis of the hands, hand function may be impaired due to the development of painful fissuring and cracking.
What does contact dermatitis look like?
The hands are the commonest area on which contact dermatitis develops, followed by the arms, neck and face. After contact with the irritant or allergenic substance, the skin may become red, bumpy, blistered, scaly and oozing.
How will it be diagnosed?
Irritant contact dermatitis may be suspected from the history of exposure to irritating substances, bearing in mind the patient’s occupations, lifestyle and hobbies. The appearances will confirm to the clinician that this is a type of dermatitis.
Allergic contact dermatitis is diagnosed by a test available in specialist dermatology departments known as patch testing (see separate Patient Information Leaflet). This involves placing patches containing known allergens on the back. The patches are taken off after 2 days, and the tested skin is examined at the time and after a further 2 days for the development of a small localised area of dermatitis (a ‘positive patch test’). The dermatologist then advises the individual which contact allergens to avoid.
Can contact dermatitis be cured?
Avoidance of skin contact with irritants or allergens will prevent development of contact dermatitis. Sometimes this may entail the need for a change in occupation, eg if a hairdresser is allergic to hair dyes or a nail beautician to nail cosmetics (acrylates).
If patch testing shows allergy to a specific allergen, then avoiding that allergen will usually lead to a big improvement or even complete clearance of the allergic contact dermatitis.
How can contact dermatitis be treated?
The main way of treating contact dermatitis is to identify the cause and remove the source of the irritant chemical or allergen from contact with the skin. Complete avoidance is not always easy. Therefore, measures to protect the skin, such as wearing gloves, improving the skin barrier with regular emollient creams, and avoiding contact with soap and detergents (see separate leaflet on hand dermatitis), are important. Exposure to irritants or allergens in certain occupations may be the cause and may lead to the need for a change in working practice or job.
It may take several months for contact dermatitis to settle. Steroid creams and moisturisers are used to reduce the inflammation of the skin. Topical steroid creams (topical corticosteroids)come in different strengths. It is important to use the right strength for the right length of time. A doctor or nurse can advise on this. It is also very important to protect the skin by using an emollient several times a day. Thick emollients are best for the hands and other affected areas in the evenings. In addition, lighter or gel-based ones should be used very frequently during the day. It is important to find one (or more) that you like to use so that you will use emollients very frequently.
People with very severe contact dermatitis may occasionally need other treatments taken orally (by mouth) such as steroid tablets and oral antibiotics or rarely medicines such as ciclosporin, methotrexate or alitretinoin; these are normally prescribed by hospital dermatologists.
CAUTION:
This leaflet mentions ‘emollients’ (moisturisers). Emollients, creams, lotions and ointments contain oils. When emollient products get in contact with dressings, clothing, bed linen or hair, there is a danger that they could catch fire more easily. There is still a risk if the emollient products have dried. People using skincare or haircare products should be very careful near naked flames or lit cigarettes. Wash clothing daily and bedlinen frequently, if they are in contact with emollients. This may not remove the risk completely, even at high temperatures. Caution is still needed. More information may be obtained at https://www.gov.uk/guidance/safe-use-of-emollient-skin-creams-to-treat-dry-skin-conditions.
What can I do?
- If you think you might have contact dermatitis, you should think about measures to protect your skin, such as wearing gloves and avoiding skin contact with soaps and detergents as much as possible.
- Improve your skin barrier by applying non-perfumed emollient creams or gels (moisturisers) several times a day, and a greasier ointment at night.
- Avoid the chemicals or substances which are causing the irritant or allergic reaction
- Take time to look after your skin both at home and at work and follow your doctor’s advice on using the various creams and treatments.
Images DermNetNZ.