FAQ with Dr Liew: “What Is Skin Allergy?”

What is skin allergy?

Skin allergy is generally known as eczema and urticaria. Eczema is a common recurrent itchy skin condition among babies, children and adult. Eczema presents with red inflamed dry patches of skin, usually in the skin folds but can be any parts of the skin in severe cases, therefore affecting quality of life. It usually runs in the family and there may be a personal or family history of asthma and allergic rhinitis.

Urticaria is also a common skin phenomenon where the skin suddenly develops itchy localized or generalized swelling, which looks like mosquito bites. The itchy rash usually subsides after several hours but may recur the following day for a few weeks.

What is the cause of skin allergy?

There are many contributing factors for the flare up of eczema. In eczema skin, the skin barrier is impaired due to underlying genetic mutation to the top layer of the skin, allowing environmental agents, such as house dust mites, fragrance, weather change, pets, etc to irritate the skin. In addition, other causes such as skin infection, stress and sometimes food (especially in young children) can also be the triggering factor to the flare.

As for urticaria, the cause is usually unknown. In acute cases (where the rash usually lasts for about 6 weeks), the common cause is a recent viral infection, medications or food. In more chronic cases, the cause can be due to change in environment temperature, pressure on the skin, exercise, or perhaps due to underlying thyroid disease or diabetes or other internal causes.

What tests can be done to determine the cause?

In eczema cases, in particular if there is a history to suggest food or environmental allergies, skin prick test or blood test can be arranged to determine if you have a specific allergy.

Skin prick test can be done easily and the results is available within 15 mins, whilst the blood test results will take between 1 to 3 weeks. In cases where the eczema could be due to contactants, e.g. hair dye, metals, fragrance, preservatives in creams, we can arrange patch test to be done.

Patch test procedure involves applying at least 3 adhesives panels of allergens, usually on the back for 3 days and by the 5 th day, your dermatologist will check you skin if you have any reactions to the allergens. Between the third day and the fifth day, it is advisable that you do not shower or exercise. He/she will advised accordingly if there is any positive reactions.

In urticaria cases and where again there may be a suspected allergy, skin prick test or blood test can be arranged. Patch test is not recommended for urticaria.

With all the mentioned allergy tests, it is best to do it when you skin is much calmer and to avoid any oral antihistamines for 1 week and oral steroid for 2 weeks before the test.

What can I do to make my skin condition better?

In eczema cases, choosing the right moisturizer and moisturizing wash for your skin is important. Moisturisers should be used on a daily basis to prevent a flare. If there is any rash that does not subside, it is advisable to use some topical steroid to alleviate the inflammation and hence the itch, before skin infection happens. Topical steroid cream is very safe as long as it is used appropriately under medical supervision. However, for more delicate skin, e.g. around the eyes or face, a steroid sparing cream that contains tacrolimus can be used as well, under medical supervision. In more severe cases, your dermatologist will be able to counsel you on the next appropriate treatment plans, e.g. wet wrap therapy (in children), phototherapy or oral medications can be used to suppress the eczema rash.

In urticaria cases, oral antihistamines should be taken on a daily basis for a period of time, depending on the severity on your rash. There are many types of oral antihistamines, sedating and non sedating type. Cooling moisturizer can be used as well to alleviate the itch as further scratching of the skin may aggravate the skin condition. In severe cases, oral medication as well as biologic injections can be used to suppress the flare.

What is the prognosis of these skin allergy conditions?

Majority of eczema cases are managed with regular moisturization and occasional use of mild topical steroid. In young infant or toddler, their eczema will usually improve later in childhood. In a small number of cases, their eczema may deteriorate for many reasons mentioned above, together with lack of knowledge and counselling on management of eczema.

In most urticaria cases, their skin condition will improve within 2 months. In more chronic severe cases, it can lasts for months and usually up to 5 years.