Atopic What an Test Can Tell You

What is an Atopic Patch Test?

An atopic patch test involves placing a small amount of allergen on the surface of the skin and then covering that area with a bandage, thereby introducing the allergen to your immune system. An atopic patch test is conducted to determine if that exposed skin develops a reaction and becomes itchy, red, or bumpy, indicating a delayed-type hypersensitivity reaction. This type of reaction is often seen with allergic contact dermatitis, but it can also occur with other conditions. Your dermatologist may recommend an atopic patch test if:

*You have symptoms of allergic contact dermatitis, such as a red, itchy, scaly rash that develops where your skin has come into contact with an allergen.

*Patch testing can identify the specific allergen causing the reaction, which can help guide treatment decisions and allow you to take steps to avoid it.

Atopic patch testing can also be useful for diagnosing other types of allergies, such as food allergies and inhalant allergies.

What to expect?

Before the test: Your doctor or nurse will review your medical history and symptoms and ask you to avoid using certain skin products, such as lotions or sunscreen, for a few days before the test.

During the test: The doctor or nurse will clean the areas of the skin where the patches will be placed. They will then apply the patches, which contain the allergens, and cover them with bandages. The patches are usually removed 48 hours after they are applied.

After the test: Once the patches are removed, the doctor or nurse will note any reactions on your skin. If a reaction occurs, it will typically appear within 24 to 48 hours and may include redness, swelling, itching, or blisters.

Patch Test Results

Depending on the severity of skin reactions, the results may be:

Negative: No reaction at any site.

Irritant: Mild redness that looks similar to a sunburn; indicates a reaction to the substance (irritants can dry and chap skin).

Positive: Severe redness, bumps, or blisters at the site where the allergen is; means you are allergic to that allergen.

Indeterminate: Weak reaction that is less than positive but more than negative; means it's unclear if there's an allergy.

False positive: Rare, but this is when a reaction develops but you are not actually allergic to the substance. Results are usually ready within a few days. Your doctor will discuss the meaning of your results and may recommend further care or suggest modifications to your lifestyle in order to avoid the allergens that you're allergic to.