I am 37-year-old woman of Caucasian origin, suffering from various types of allergic skin reactions since several years. Recently, I was told to get a skin allergy patch test done. Can you explain what this test is?

Skin allergic reactions pose a significant diagnostic challenge. This is because of the complex nature of allergy as a disorder and the complexity of the various immunological mechanisms involved in causing the allergy.

An allergy patch test is mainly recommended for patients whose clinical features and blood investigations fail in helping physicians reach a conclusive diagnosis.

The test patches are fixed on the sufferer’s upper back. However, in certain cases, if the upper back is clear of lesions, the test patches can be placed on upper arms.

The inner surfaces of these patches contain several small chambers that have pre-filled allergens of most commonly suspected chemicals or metals.

The patches are removed after 48-72 hours. The doctor then examines the tested areas of the skin and decides the positivity or negativity of the test based on the presence or absence of a reaction. The positive reactions produce redness under the chambers containing the most likely allergen, which is later correlated with the labels on top of these chambers to name the positive allergen.

The degree of redness determines the severity grade of the reaction.

The detailed documented information is handed over to the patient with advice on how to avoid the positively detected allergy-inducing substances. This results in significant reduction and often total elimination of sufferer’s skin complaints.