Allergy testing is done to determine the exact cause of allergic reactions in a patient. Allergy testing is of two types generally. One involved the skin and the other involving the blood. Though either type of tests can be conducted to determine the allergen yet the skin test are more popular because these are more rapid and also more reliable. Again, skin test is also less expensive also if compared to blood tests.

Skin Test

In test are the most dependable allergy tests. In a skin test a small drop of the suspected allergen is placed in the elbow, or the back of the suffering individual to see whether allergic symptoms appear or not. The results are generally available within twenty minutes.

There are three types of skin tests available. They are:

Skin Patch Test: This kind of allergy testing is conducted to detect a skin allergy known as Contact Dermatitis and is not used for other allergies. For this test the allergen solution is placed on a pad and is taped to the skin for 24 to 72 hours and is monitored for allergic reactions. Skin Prick Test: This is conducted by putting a drop of the solution which contains a suspected allergen on the skin and a series of scratches or needle pricks allows the solution to enter the skin. If the skin develops itchy and red areas it actually suggests that the person is allergic to that particular allergen. The result is called positive reaction.

Intradermal Test: Another type of allergy testing in skin is known as Intradermal Test. If a prick test shows negative results but the person has history of allergic reactions to a particular product then intradermal test is conducted to make sure that the suspected allergen is the actual cause of allergy. In this test a small quantity of the allergen solution is injected inside the skin of the person who is suffering from allergic reactions. If the reactions appear then the cause of the allergy is determined and makes treatment easier.

Blood Test(RAST)

Sometimes blood tests are done to determine allergy causes when the patient is unable to take the skin test. Blood tests are Allergy testing through blood searches for antibodies in blood. This test is called RAST or Radioallergosorbent Test. By this test it can be known how much of the specific IgE antibodies are there in blood. If there are antibodies then the reactions are truly allergic. But the results of this kind of tests are not available as fast as those of skin test.

Some other blood tests are there for allergy determination. They are:

• Blood Differential Test
• Serum Immunoglobulin Electrophoresis
• Absolute Eosinophil Count

One thing which is important in regard to allergy testing is that some times a positive result may be derived from a skin test regarding a specific allergen. But it does not mean that the person will definitely experience allergy symptoms from that particular allergen. For this reason allergy specialists only comes to a particular conclusion after studying the results as well as the symptoms in that person for a reasonably long period of time.