A person receiving a<unk>  An array of allergens to be used in testing A microscopic amount of an allergen is introduced to a patient's<unk>  by various means: *<unk>  prick test: pricking the<unk>  with a needle or pin containing a small amount of the allergen. *<unk>  scratch test: a deep dermic scratch is performed with help of the blunt bottom of a lancet. * Intradermic test: a tiny quantity of allergen is injected under the dermis with a hypodermic syringe. *<unk>  scrape Test: a superficial scrape is performed with help of the back of a needle to remove the superficial layer of the epidermis. * Patch test: applying a patch to the<unk> , where the patch contains the allergen If an immuno-response is seen in the form of a rash, urticaria (hives), or anaphylaxis it can be concluded that the patient has a hypersensitivity (or allergy) to that allergen. Further testing can be done to identify the particular allergen. The "skin scratch test" as it is called, is not very commonly used due to the increased likelihood of infection. On the other hand, the "skin scrape test" is painless, does not leave residual pigmentation, and does not have a risk of infection, since it is limited to the superficial layer of the<unk> . Some allergies are identified in a few minutes but others may take several days. In all cases where the test is positive, the<unk>  will become raised, red, and appear itchy. The results are recorded - larger wheals indicating that the subject is more sensitive to that particular allergen. A negative test does not conclusively rule out an allergy; occasionally, the concentration needs to be adjusted, or the body fails to elicit a response. Immediate reactions tests<unk>  testing on arm In the prick, scratch and scrape tests, a few drops of the purified allergen are gently pricked on to the<unk>  surface, usually the forearm. This test is usually done in order to identify allergies to pet dander, dust, pollen, foods or dust mites. Intradermal injections are done by injecting a small amount of allergen just beneath the<unk>  surface. The test is done to assess allergies to drugs like penicillin or bee venom.<unk>  testing on back To ensure that the<unk>  is reacting in the way it is supposed to, all<unk> s are also performed with proven allergens like histamine, and non-allergens like glycerin. The majority of people do react to histamine and do not react to glycerin. If the<unk>  does not react appropriately to these allergens then it most likely will not react to the other allergens. These results are interpreted as falsely negative. Delayed reactions tests Patch test The patch test simply uses a large patch that has different allergens on it. The patch is applied to the<unk> , usually on the back. The allergens on the patch include latex, medications, preservatives, hair dyes, fragrances, resins, and various metals.<unk>  end point titration Also called an intradermal test, this<unk>  end point titration (SET) uses an intradermal injection of allergens at increasing concentrations to measure allergic response. To prevent a severe allergic reaction, the test is started with a very dilute solution. After 10 minutes, the injection site is measured to look for growth of wheal, a small swelling of the<unk> . Two millimeters of growth in 10 minutes is considered positive. If 2 mm of growth is noted, then a second injection at a higher concentration is given to confirm the response. The end point is the concentration of antigen that causes an increase in the size of the wheal followed by confirmatory whealing. If the wheal grows larger than 13 mm, then no further injections are given since this is considered a major reaction.
Skin allergy test
Allergy test
Patch test
Chemosensitivity assay
Radioallergosorbent test
Contact activation system
Nasal provocation test
Bronchial challenge test