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Allergic Contact Dermatitis (Eczema)
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Allergic Contact Dermatitis

Dr. Richard Thomas, MD, FRCPC

What is allergic contact dermatitis?

Allergic contact dermatitis occurs when something has come into contact with your skin which causes your immune system to respond, causing rashes, swelling, and redness. This is a separate from a condition called irritant contact dermatitis, which is caused by the breakdown of the skin’s protective capabilities by repeated exposure to damaging irritants.

How do you know if it’s allergic contact dermatitis?

Red swollen blisters are common at the location of contact, however, these blisters may spread to other areas over time. The skin will often become scaly over time.

Is it possible that I have a food allergy?

It’s certainly possible. Food allergies and atopic eczema are often closely related, especially in children. Common high risk foods include eggs, milk, soy, and wheat. Other risky foods include shellfish and tomatoes. Other common allergens include alcohol, lavender oil, cinnamon, vitamin E, rosemary, and tea-tree oil.

While a food allergy is often difficult to determine with accuracy, there are tests that you can perform. Abstain from the food product that you suspect you may be allergic to. After a few weeks, rub the suspected product on the forearms two or three times a day. If you are allergic, you will likely encounter a reaction to it. A dermatologist can also provide patch tests to determine if you have certain allergies.

What are the common products that cause allergic reactions?

In descending order:

Skin Care products: 28%
Haircare products: 24%
Facial cosmetics: 11%
Nail cosmetics: 8%
Fragrance products: 7%

What are in these products that trigger the reactions?

Balsam of Peru: A common natural fragrance that is found in cosmetics, it is also present in cloves and cinnamon.

Formaldehyde: Contained in cigarettes, paint, paper, plastic bottles, and textiles in small amounts, it is a common trigger for allergic reactions.

Fragrances: Often found in cosmetics, these can trigger reactions.

Neomycin: An antibiotic, found inside topical creams.

Nickel: A very common source of allergies, nickel is often found in jewellery.

Quaternium 15: A preservative found in many cosmetic products, this can be a cause of allergic dermatitis in people who have sensitive skin. People who are allergic to formaldehyde, are often allergic to quaternium.

Thimerosal: A preservative used in cosmetics, which can trigger allergic reactions in some.

What can I do about my allergies?

Avoidance of the allergens is the only real cure. Identify the source of your allergies first. A dermatologist can conduct a battery of allergy tests to determine which substances you are allergic to, and take care to avoid products that contain these allergens.

If I am having an allergic reaction, what can I do?

  • Do not scratch the affected area, as it can lead to scarring, increased pigmentation (darkening of the skin), thickening of the skin, and infection. Instead, gently pat the skin, relieving the itch.
  • Limit contact with hot water as it dries the skin.
  • Avoid soaps and detergents as it can aggravate dermatitis.
  • Avoid contact with antiseptics or alcohol.
  • Use emollients such as Aquaphor or Vaseline on the affected area if the skin becomes dry.
  • Apply damp compresses on the irritated areas to limit itching.
  • Avoid contact with the suspected allergen.

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