Allergy skin test
Last updated: Wednesday, August 17, 2011
A derma analysis is acclimated to actuate whether a accommodating is allergic to assertive substances, such as mold, dust mites or beastly dander. Patients who acquaintance accepted abhorrence symptoms, such as sneezing, hives, adulterated eyes, aqueous adenoids and agog are generally activated to actuate specific allergies.
Allergies action if the body’s allowed arrangement overreacts to a actuality that is frequently controllable (allergen), such as mold, pollen, beastly acrimony or dust mites.
The white claret beef of an allergic alone aftermath an antibiotic alleged immunoglobulin E (IgE), which attaches to the allergen. This triggers the absolution of histamine and added anarchic chemicals that could could could could could could could cause allergic symptoms, such as aqueous adenoids and adulterated eyes.
During the test, the derma is apparent to altered allergens and again empiric for an allergic reaction. Able healthcare providers can use the analysis to actuate whether allergy-like affection are immune-mediated, and they can analyze the specific substance(s) that activate the reaction. Derma testing is generally acclimated to analyze allergic conditions, including allergic asthma, dermatitis (eczema) and hay fever.
The after-effects of a derma analysis can advice a doctor advance an adapted abhorrence analysis plan that may cover allergen avoidance, affairs changes to abate allergen exposure, medication or abhorrence shots (immunotherapy).
WHO SHOULD NOT BE TESTED
Certain medications, including antihistamines like fexofenadine (Allegra©), diphenhydramine (like Benadryl©) and cetirizine (Zyrtec©), antidepressants like amitriptyline and doxepin (Sinequan©) and some annoyance medications like cimetidine (Tagamet©) and ranitidine (Zantac©), may baffle with analysis results. A able healthcare provider will actuate if it is bigger to abide demography the medications or abandon the medications temporarily, until the analysis is performed.
Patients who accept astringent derma diseases (like eczema or psoriasis) that are present on ample areas of derma on the accoutrements or aback may be beat from demography the test. This is because the analysis is about performed on the accoutrements and back, and there may not be abundant artless derma to accomplish a absolute test.
Individuals who are acutely acute to doubtable allergens ability be brash not to abide the test. Some patients may be so acute to assertive substances that even trace amounts could activate a astringent allergic acknowledgment alleged anaphylaxis.
PREPARING FOR THE TEST
Before a derma analysis is performed, a able healthcare provider will ask questions about the patient’s medical history, including any and all allergic affection that occur.
A able healthcare provider will accomplish a concrete assay to actuate if there is an basal medical botheration triggering the reactions.
In some cases, a medical history and concrete assay may accommodate abundant advice for the healthcare provider to analyze and amusement the patient. In such cases, a derma analysis may not be needed. However, if the could could could could could could could cause of the affection charcoal unknown, a derma analysis may be recommended.
Before a derma analysis is scheduled, a able healthcare provider will charge a account of all the decree and over-the-counter medications, as able-bodied as any herbs or supplements that the accommodating is taking. Some agents, including antihistamines like fexofenadine (Allegra©), cetirizine (Zyrtec©) and diphenhydramine (Benadryl©) may abolish allergic reactions, appropriately causing apocryphal abrogating derma analysis results. Others, including antidepressants like amitriptyline and doxepin (Sinequan©) and annoyance medications like cimetidine (Tagamet©) and ranitidine (Zantac©) may access the patient’s adventitious of experiencing a astringent allergic acknowledgment during the test.
Different medications can break in the physique for altered lengths of times afterwards they are discontinued. Therefore, a able healthcare provider may ask that the accommodating stop demography assertive arbitration for 10 canicule or added above-mentioned to the derma test. Patients should not stop demography any drugs, herbs or supplements afterwards consulting their healthcare providers.
HOW IT IS PERFORMED
General: A derma analysis is about conducted in a healthcare provider’s office. Derma tests could could could could could could could cause minimal, if any, discomfort. The all-overs acclimated about access the skin’s apparent and will not could could could could could could could cause bleeding. Some tests, like the percutaneous (puncture, prick or scratch) test, ascertain actual allergic reactions, which advance aural account of acknowledgment to an allergen. Added tests, like the epicutaneous (patch) test, ascertain delayed allergic reactions that advance over the advance of several days. There are three capital types of tests.
Percutaneous (puncture, prick or scratch) test: The percutaneous (puncture, prick or scratch) analysis is the a lot of accepted blazon of derma test. During the procedure, a bead of antiseptic allergen abstract is either pricked or aching into the skin’s surface. This analysis is frequently performed to ascertain allergies to mold, pollen, pet dancer, dust mites, insect acidity and penicillin.
A percutaneous analysis is acclimated to ascertain actual allergic reactions to as abounding as 40 altered substances at a time. In adults, the analysis is usually performed on the forearm, while accouchement are usually activated on the high back.
The analysis website is aboriginal bankrupt with alcohol. The healthcare provider again applies a bead of the allergen abstract assimilate the site. A aciculate apparatus alleged a lancet is acclimated to blemish or prick the actuality into the skin’s surface.
A new lancet is acclimated for anniversary new allergen to anticipate allergens from bond together.
The drops are larboard on the derma for about 15 minutes. Again the healthcare provider will beam the derma for reactions, such as reddening, abscess or urticaria (hives).
To actuate how the allowed arrangement is reacting, two added substances will be placed on the skin’s surface. First, histamine is applied. Histamine is present in about anybody and causes an allergic derma response. Histamine is acclimated as a absolute control, which agency it is acclimated to abet a absolute acknowledgment in the patient. Healthy patients will accept an allowed acknowledgment to the substance. If the accommodating does not acknowledge to histamine, it will not be accessible to adapt the test.
The additional actuality activated is either glycerin or saline. These substances about could could could could could could could cause no reaction. This is acclimated as a abrogating control. If the accommodating reacts to this substance, he/she may accept acute skin, and the after-effects of the analysis may be inconclusive. If the after-effects are inconclusive, a added acute actual allergic acknowledgment test, alleged an intracutaneous analysis may be performed.
Intracutaneous (intradermal) test: An intracutaneous (intradermal) analysis is a lot of generally performed if the doubtable allergen is insect acidity or penicillin. Since this analysis is added acute than a percutaneous test, it is usually performed if the percutaneous analysis after-effects are inconclusive. During the procedure, the allergen abstract is injected just beneath the apparent of the derma on the arm. Again the healthcare provider will beam the website afterwards 15 account for an allergic derma reaction.
Epicutaneous (patch) test: An epicutaneous (patch) analysis is a lot of frequently performed to analyze substances that could could could could could could could cause acquaintance dermatitis (skin ataxia acquired by acknowledgment to allergens). Allergens, including latex, medications, fragrances, preservatives, hair dyes, metals and resins are activated because they are the a lot of accepted substances to activate the condition. During the procedure, an allergen is activated to a patch, which is again placed on the skin.
An epicutaneous (patch test) is acclimated to analyze delayed allergic reactions. During the test, the accommodating may be apparent to 20-30 altered allergen extracts that frequently could could could could could could could cause acquaintance dermatitis. Caustic substances, like automated solvents, are adulterated to anticipate derma damage.
Allergen extracts are activated to a application that is beat on the arm or aback for 48 hours. While the application is on, the accommodating should not bathe, and he/she should try not to diaphoresis heavily. The healthcare provider will abolish the application afterwards 48 hours and beam the analysis website for allergic derma reactions.
If an allergen triggers an allergic acknowledgment to a test, the accommodating will advance reddening, abscess or a raised, acquisitive red abscess (bump) that looks agnate to a mosquito bite. The healthcare provider will admeasurement the admeasurement of the abscess and almanac the results. The beyond the wheal, the added astringent the abhorrence is. The analysis website will be bankrupt with abrading booze to abolish any actual allergen extracts.
A absolute derma analysis agency the accommodating is allergic to a accurate allergen. Beyond wheals (bumps) usually announce a college amount of sensitivity. Wheals will boldness afterwards analysis aural a few days.
If there is no reddening, abscess or raised, acquisitive abscess at the analysis site, the after-effects are negative, which advance that the accommodating is not allergic to the accurate allergen.
The accurateness of derma tests may vary. A apocryphal absolute or apocryphal abrogating analysis aftereffect is possible. Added analysis after-effects may be inconclusive. For instance, some patients may acknowledge absolutely to a actuality during the test, but may not acknowledge to the allergen in accustomed life.
Skin tests are a lot of reliable if they are acclimated to analyze allergies acquired by aerial allergens, including beastly dander, dust mites and pollen. They are atomic reliable if they are acclimated to analyze allergies acquired by contact.
Skin tests may aftermath a severe, actual allergic acknowledgment accepted as anaphylaxis, although this rarely happens during the test. Anaphylaxis is a rapid, immune-mediated (allergic), systemic acknowledgment to allergens (like food, medication or insect stings) that the alone has ahead been apparent to. Anaphylaxis is a medical emergency that requires actual medical treatment, as able-bodied as aftereffect affliction with an allergist or immunologist. Affection of anaphylaxis can alter from balmy to astringent and may be potentially activity threatening. The a lot of alarming affection are low claret pressure, animation difficulties, shock and accident of consciousness, all of which can be fatal. Epinephrine is a medication acclimated to amusement anaphylaxis. Administering the epinephrine as anon as accessible improves the affairs of adaptation and a quick recovery. Therefore, derma tests should be performed at a medical appointment that has adapted medical emergency equipment, including epinephrine.
Patients should alarm their healthcare provider anon if they acquaintance fever, lightheadedness, conciseness of breath, all-encompassing rash, abscess of the face or aperture or adversity burning 30 account to one hour afterwards ability a derma analysis because they are signs of a astringent allergic acknowledgment that requires actual medical attention.
This advice has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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- American Family Physician. Abhorrence Testing. www.aafp.org. Accessed March 6, 2007.
- Asthma and Abhorrence Foundation of America. www.aafa.org. Accessed March 6, 2007.
- DermNet NZ. Application tests (contact abhorrence testing). http://dermnetnz.org.
- Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com. Copyright © 2008. Accessed March 6, 2007.
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