Allergy tests are often used by allergists/immunologists to determine if a person's symptoms are caused by allergies. However, the primary goal of most allergy tests is to identify the specific allergen that triggers the patient’s allergic reactions.

An allergy occurs when the body overreacts to an allergen (a substance that is normally harmless) because it mistakes it for a threat. In such cases, the immune system produces certain antibodies to protect the body from the allergen. This, in turn, triggers an allergic reaction, which may include symptoms such as hives, runny nose, watery eyes and wheezing.

The most effective method of preventing an allergic reaction is to completely avoid contact with the triggering allergen. Therefore, identifying the specific allergen to which a person is sensitive is a crucial part of overall allergy management.

Allergy testing can be conducted on patients of any age. They are frequently used to uncover reactions to a variety of potential allergens, including:

• Tree, weed and grass pollens
• Molds
• Household dust and dust mites
• Animal dander and feathers
• Foods (e.g., milk, eggs, peanuts, wheat)
• Medications
• Insect venom
• Cockroach debris
• Latex 

The first step in diagnosing any condition is usually a thorough physical examination that includes a complete medical history. A physician may ask detailed questions about any family history of allergies. Patients can help by preparing a list of allergies other family members may experience, as well as by detailing how, when and under what conditions their allergies occur. The physician may also ask the patient to keep a diary of this information.

Patients will also be questioned about their lifestyle at home, work or school (e.g., eating habits, hobbies). This information will further help the physician pinpoint the allergens causing the patient’s allergic reactions.

The three primary groups of allergy tests used in the diagnosis and treatment of allergy-related problems include:

• Allergy skin test. A small amount of an allergen is introduced to the patient’s skin to determine if the person is allergic to that substance.
  
  

  

  
  
• Allergy blood tests. A patent’s blood sample is tested for substances that indicate an allergic reaction has occurred to a particular allergen.
  
  
• Food allergy tests. Patients may be asked to avoid (or, in rare cases, to ingest) specific foods according to a timetable to determine if allergic reactions can be prevented.

In addition, physicians may order tests to determine lung or nasal function or to rule out other causes of allergy-like symptoms.

In some rare circumstances, a physician may recommend a patient participate in an allergen inhalation challenge. This type of testing involves the inhalation of allergens to see if an allergic reaction occurs. Because this test can potentially cause a dangerous allergic response in a patient, it is used only when more conventional testing methods are impractical. This type of test is occasionally used to confirm the effectiveness of immunotherapy treatments.  

Complementary and alternative medicine (CAM) allergy tests also have been introduced as alternative approaches to diagnosing allergies. Proponents of these tests contend that substances such as chemicals in products, micro-organisms such as yeasts, and human hormones play a major role in allergic reactions.

These claims have not been proven, and many of these tests have been shown to be ineffective. If a physician recommends these tests, patients may want to consider getting a second opinion:

• Cytotoxicity blood test, in which white blood cells are examined to see if an allergen causes them to change shape.
  
  
• Applied kinesiology, in which the patient's arm strength is tested after test substances are placed in the patient's mouth or hand.
  
  
• Subcutaneous or sublingual provocation testing, in which substances are injected under the skin or placed under the tongue until symptoms appear.
  
  
• Neutralization testing, in which decreasing amounts of a substance are given until symptoms no longer appear.
  
  
• ELISA/ACT (not to be confused with ELISA, which is often used to test for autoimmune diseases and sometimes for allergies).
  
  
• Electroacupuncture biofeedback, which involves the measurement of electrical properties at a person's acupuncture points.
  
  
• Urine autoinjection, which involves the intramuscular injection of sterilized urine back into the person who excreted the urine.
  
  
• Skin titration (Rinkel method).
  
  
• Candidiasis allergy theory.
  
  
• Basophil histamine release.

Patients are encouraged to discuss any alternative tests or therapies they are considering with a board certified allergist/immunologist.