Allergic Reaction Tests and Diagnosis

In order to find out the substances that cause an individual to develop an allergic reaction, allergy skin tests need to be performed.

Allergy skin tests have typically three methods. These include the skin prick test, intradermal skin test and patch testing

Skin Prick Test – The test entails subjecting your skin to minimal amounts of substances suspected of causing allergic reactions on your skin especially on the back, upper arm and forearm. The skin is pricked in order for the allergen to enter the surface of the skin. Your doctor or health care provider monitors the treated skin to check for any redness and swelling and other kinds of reaction. Typically the results of the test can be evidenced within 20 minutes. Different types of allergens can be tested all at once in this type of test.

Intradermal Skin Test – This is a test wherein minimal amounts of allergen are injected into your skin. Your doctor will watch and wait for any signs of reaction on the treated skin. Intradermal skin testing is usually used to see if you’re allergic to substances such as insect venom or drugs such as penicillin.

Patch Testing – This type of test is a diagnostic test to ascertain the cause of the skin reactions after the allergen comes into contact with the skin. This test enables potential allergens to be attached to the skin for two whole days. After three or four days, the doctor will evaluate the exposed skin.

Prior to any type of allergy testing, your doctor may query you about:

Foods and eating habits
Where you work and live

Also prior to any allergy test, your healthcare provider/doctor will require you to temporarily stop taking certain allergy medicines because these drugs may affect the outcomes of your skin tests.

Because the skin needs to be pricked, these skin tests can cause some pain and discomfort when your skin is pricked. The substances used in these tests may cause symptoms like skin rash, watery red eyes, stuffy nose and itching in you.

One rare occasions, individuals can suffer from very severe allergic reactions during a skin test. One of these reactions is termed anaphylaxis and this reaction is potentially lethal to the sufferer. Anaphylaxis can occur in an intradermal test. Your doctor needs to anticipate for this eventuality in order to treat the reaction properly.

Allergy skin tests are often performed if the patient suffers from:

Venom allergy
Penicillin allergy – This is the only kind of drug allergy that can be tested utilizing skin tests. Using skin tests for other kinds of drugs can be potentially dangerous
Dermatitis (skin rashes) – This skin condition causes the skin to become swollen, sore or red after the skin comes into contact with an allergen
Food allergies
Angioedema and hives
Asthma symptoms and allergic rhinitis (hay fever) that poorly respond to medicines

Food allergies can also be diagnosed by a prick skin test. There are two reasons why intradermal tests are not applied for food allergies: one reason is that these tests often come up with results that have high false-positives; the second reason is that they can cause serious allergic reactions.

When a skin test has a negative result, this implies that the skin has no response to the suspected allergen. Simply stating, a negative reaction usually means you have no allergic reaction to the substance although it rarely happens that a person who is allergic to a substance can still show a negative skin test result.

When a skin test shows a positive result, this implies you are allergic to the substance and you doctor will usually see the development of a wheal in the treated site. A wheal is a skin condition that looks like raised and red skin.

Often, a positive result means the symptoms you are having are due to exposure to that substance and a stronger response shows that you have high sensitivity to that substance. Although they may show a positive result in the allergy skin test, some individuals may not have any issue at all with these substances in their daily life.

The good thing about allergy skin tests is that they are quite reliable and accurate.  The problem with these tests, however, is that when the amount of the substance/allergen given is large, people who may not be really allergic to the substance will manifest a positive test result.

Your doctor will use your skin test results as well as your symptoms to determine modifications of lifestyle you need to make in order to avoid the substances that are causing your allergic reactions.

Christina Prieto is an Orlando acupuncturist, a certified Yoga instructor and the founder of Harmony Wellness center in central Florida.

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