Allergy patch test. Tissue paper with patches (round) to be used in an allergy patch test. Small amounts of common allergens are placed on labelled patches. Eight of the patches test (clockwise from top): peanuts, kiwi fruit, wheat grains (contain gluten), shellfish, soya beans, common household chemicals, household dust, and flower pollen. The patches are then placed in contact with the skin of test subjects to discover if they are allergic to any of these substances. If they are, allergic reactions cause the skin around the relevant patch to become inflamed. By knowing what they are allergic to, the subjects can alter their diet or behaviour to avoid the allergen.