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Patch testing is a specialized diagnostic method used to identify substances that cause allergic contact dermatitis, a type of skin reaction that occurs when the skin comes into contact with certain allergens. These reactions often appear as itchy rashes, redness, or eczema-like irritation.
At Certified Allergy & Asthma Consultants, we evaluate patients throughout New York’s Capital Region who experience persistent skin irritation or suspected contact allergies. Patch testing can help identify specific substances that may be triggering these reactions so patients can avoid them and prevent future flare-ups.
Unlike many other allergy tests that look for immediate allergic reactions, patch testing is designed to detect delayed allergic reactions that develop over several days after skin exposure to an allergen.
Patch testing is a diagnostic test used to determine whether certain substances cause allergic inflammation of the skin. It is most commonly used to evaluate allergic contact dermatitis, a type of allergy that occurs when the skin reacts to materials it touches.
During the test, small amounts of potential allergens are applied to the skin using adhesive patches. These patches are typically placed on the back and left in place for a period of time so the skin can react if an allergy is present.
Patch testing may help identify allergies to substances such as:
Identifying the specific substances responsible for skin reactions can help guide treatment and avoidance strategies.
Patch testing is most often used to evaluate allergic contact dermatitis, a delayed immune reaction that occurs when the skin becomes sensitized to certain substances.
Patch testing can help determine whether a rash is caused by an allergic reaction to a specific substance rather than irritation or another skin condition.
Patch testing is typically completed over several days and may involve multiple visits.
The patches are removed and the skin is examined for signs of reaction. Because allergic contact dermatitis develops slowly, the skin may be evaluated again several days later to detect delayed reactions.
Your allergist reviews the results and determines whether any of the tested substances caused an allergic reaction.
Patch test reactions are interpreted by examining the skin where the allergens were applied.
A positive reaction may appear as:
A positive result indicates that the immune system recognizes the tested substance as an allergen and that exposure to that substance may trigger skin reactions.
Your allergist will review the results with you and provide guidance on how to avoid identified allergens in everyday products or environments.
Once an allergen has been identified through patch testing, the most effective treatment is reading labels and avoiding the substance responsible for the reaction.
Your allergist may recommend:
With proper diagnosis and avoidance strategies, many patients experience significant improvement in their skin symptoms.

Patients trust Certified Allergy & Asthma Consultants for comprehensive evaluation of allergic skin conditions.
Our specialists help patients:
Accurate diagnosis through patch testing can help patients better understand their skin sensitivities and reduce future allergic reactions.