Desencadeadores e irritantes do eczema

O que é eczema?

The terms eczema and dermatitis mean much the same - an inflammation of the skin. It is a skin condition that causes red, itchy, sensitive skin which is often very dry. There are two main types of dermatitis/eczema:

Eczema atópico

This is caused by a problem from within the body. People with atopic eczema are born with a tendency for their skin to become inflamed. Various parts of the skin tend to flare up with inflammation from time to time.

Dermatite de contato

This is caused by a substance from outside the body. This typically causes patches of inflammation on areas of skin which have come into contact with the substance. If the offending substance is avoided, the skin inflammation should go away.

The rest of this leaflet is only about factors that may trigger or irritate atopic eczema. See the separate leaflet called Atopic Eczema e one called Dermatite de Contato which provide a general overview of the conditions.

What are triggers and irritants?

In most people who have atopic eczema there is no apparent reason why the eczema may flare up from time to time. However, some flare-ups may be caused (triggered) or made worse by irritants to the skin or by other factors.

This leaflet briefly discusses some possible triggers and irritants.

Soaps and detergents

Soaps and detergents remove the natural oils from the skin. This tends to make the skin dry and itchy and more sensitive to irritants.

People with atopic eczema/dermatitis should avoid soap as much as possible, and bubble bath and shower gel completely, when washing. Instead, a thick moisturiser (emollient) should be used as a soap substitute. See the separate leaflet called Emollients and Eczema Creams for details. Rubber gloves with a cotton lining should be worn when using detergents or working with other similar chemicals.

Biological detergents and fabric conditioners are known trigger factors and can irritate the skin and make some people's eczema worse. It is important to rinse clothes well when hand-washing clothes with a detergent.

Toiletries and perfumes

Some people with eczema find that the perfumes, preservatives and alcohols in toiletries and make-up can be irritating. It may be best to avoid these, or only use bland products.

Clothing

Cotton clothes should be worn next to the skin rather than potentially irritating fabrics such as wool. Some smooth man-made fabrics may be just as good as cotton.

Temperatura

Extremes of temperature, dry air and humidity may cause eczema to flare up and trigger eczema symptoms in some people. It is best to try and avoid getting either too hot or too cold if this appears to be a trigger.

Stress, habitual scratching and the itch-scratch cycle

Stress can cause eczema to flare up.

Also some people react to stress by habit scratching and It is thought that scratching can make itching worse, which then causes worse scratching. This is called the itch-scratch cycle and can make eczema worse.

It is important to try and avoid scratching eczema and, it helps to keep fingernails cut short so that any scratching is not so sharp and severe. Some people find it helps to wear cotton gloves at night if they tend to scratch in their sleep; anti-scratch mittens for babies are often very helpful. It is best to rub itchy areas with fingers rather than scratch with nails.

Some people find that relaxation exercises or similar techniques help to reduce stress. This may help to reduce habit scratching, which may help to reduce the severity of eczema.

Infecção

Infection, often introduced by scratching, can aggravate eczema. You can read more about this in the separate leaflet called Atopic Eczema.

Food allergy and eczema

1 in 10 children with atopic eczema have a alergia alimentar which can make symptoms worse. In general, it is young children with severe eczema who may have a food allergy as a trigger factor. The most common foods which cause (trigger) eczema symptoms in some people include: cow's milk, eggs, soya, wheat, fish and nuts.

How do I know if food is making eczema worse?

• Some food allergies occur immediately. Symptoms develop within two hours of eating the trigger food. Itching and scratching may worsen shortly after eating it. A common sign is redness, swelling and irritation around the mouth. Another skin symptom that may develop is urticária. In this condition, itchy, fluid-filled lumps appear on the skin - similar to nettle stings. Other symptoms may occur such as tummy (abdominal) pain, being sick (vomiting), wheezing, itchy eyes and sneezing.

• Delayed food allergy occurs in some cases. Symptoms develop 6-24 hours after eating the trigger food. Symptoms include worsening of itching and eczema. Sometimes abdominal pain and diarrhoea also occur.

If there is a suspicion that a food is making eczema symptoms worse then it is useful to keep a food diary over 4-6 weeks before seeing the doctor, aiming to record any symptoms and all foods and drink taken. It may help to identify one or more suspect foods.

Confirming a food allergy isn't always straightforward but blood tests can be of benefit and are often available via a GP. An exclusion diet is another option - in this case, the possible trigger food is cut out completely for at least 6 weeks to see if the eczema symptoms settle. The food should then be eaten again deliberately and, if the eczema gets worse, then the food should be avoided in future

House dust mite

House dust mites are tiny insects that occur in every home. They are not visible without a microscope. They mainly live in bedrooms and mattresses as part of the dust.

Many people with eczema are allergic to house dust mite. However in general, it is not usually advised to do anything about house dust mite. This is because:

• Research on whether removing house dust mites helps with eczema has so far been inconclusive. There is some evidence that reducing house dust mite may help but further research is really needed to confirm this.

• It is impossible to clear house dust mite completely from a home and it is hard work to reduce their number to a level which may be of benefit.

• Treatment with other methods such as moisturisers (emollients) and short courses of topical steroids usually works well. The effort of trying to eliminate house dust mite is not usually necessary.

It has to be stressed, it is hard work and not usually recommended. However, if you want to try to reduce the numbers of house dust mite, a separate leaflet called House Dust Mite and Pet Allergy is available.

Pets

Some parents report that symptoms in children become worse when they are in contact with pets. It is an allergy to the animal's hair or saliva which may be responsible. If there is a suspicion that a pet may be the cause, it may be worth removing the pet to another home for a while to see if symptoms improve. For further information see the separate leaflet called House Dust Mite and Pet Allergy.

Other possible triggers

Other possible factors which may trigger symptoms, or make symptoms worse, include pollen, mould, pregnancy and hormonal changes before a period in women. However, these may not be avoidable. There may also be other factors which have not yet been identified which can trigger symptoms in people who have eczema.