Skin Test
A skin test involves either a gentle prick with a drop of allergen extract on the surface of your arm or an injection of a small amount of allergen extract into the skin. This method may result in mild swelling and a reddening of the skin, which tells the doctor that you have an allergy. For most patients this method requires about one hour and is not very painful.
Blood Test (in vitro test)
A blood test can be used on its own, or to confirm a skin test's results. If specific antibodies towards one or more allergens are found in the blood, it means that you are allergic and would have an allergic reaction if exposed to those substances.