Allergies happen when a foreign substance in the body attack the immune system. There are various types of allergies a person could get. An allergy test can be conducted through a skin or blood test. Depending upon your condition, the allergy specialist recommends the test and treatment. Doctors prescribe tests according to the suspected allergen. However, the skin test can be conducted through two methods. The first type is where the allergen is placed directly into the forearm or back of the skin and then picked subsequently. A positive test is detected when the skin area becomes red and swollen. The second method injects the allergen into the skin, and the results are studied over time
