When you get allergy skin test does the needle have the original substance or something else?

Extracts of Allergen: Skin testing is a test that detects the presence of allergen-specific IgE on the surface of your skin mast cells. Allergen extracts of various aeroallergens (timothy grass, ragweed, dust mites, etc.) are pricked into the skin and if allergen-specific IgE is present on your mast cells, the cells are activated and produce localized itching, swelling, and redness.