Patch Skin Testing Q&A

What is patch skin testing?

Patch skin testing is an allergy test that exposes small areas of skin to specific types of allergens to determine if an allergic reaction occurs. Patch testing can be performed for many allergens, including chemicals, cosmetics, metals and preservatives, and it’s typically used for skin allergic reactions like atopic dermatitis and contact allergic dermatitis. During your patch skin test, small areas of skin will be exposed to allergens and then those areas will be closely monitored and evaluated over time to look for signs of irritation or other signs that indicate an allergic reaction. The length of time the allergens are left on the skin can vary based on multiple factors, including your symptoms and the type of substance being tested. The results of your patch skin testing can provide important information to help guide your treatment.

How is patch skin testing performed?

Patch skin tests are usually performed on your back or in some cases your arm. The suspected allergens are applied to your skin using special stickers “impregnated” with allergens and designed to prevent the substances from being washed or rubbed away. Patch testing often includes many substances – sometimes as many as 20 or 30 – depending on your symptoms. Once applied to the skin, the substances are allowed to remain in place for a specified period of time, typically about 48 hours, before the skin is evaluated for changes.

Is patch skin testing a good option for all patients?

Patch skin testing can be a very important tool for identifying allergies to specific substances; however, the tests may not be a good option for people with very severe allergic reactions, people with certain types of skin conditions or those who take specific types of medications.