1. Skin Injection Test
If scratch test is not recognised any result then order to intradermal skin test.
This test requires injecting a tiny amount of allergen into dermis layer to skin on forearm.
Injection site is examined after about 15 minutes for signs of allergic reaction.
Doctor may recommend this test to check for allergy to insect venom or penicillin.
Site of antigen injection- Reaction to antigen
2. Patch test
Method used to determine whether a specific substance causes allergic inflammation of patient skin.
Any individual suspected of having allergic contact dermatitis needs patch testing.
Patch test don't use needles, instead allergens are applied to patches, which are then placed on skin (on arm or back).
Patch tests can detect delayed allergic reaction which take several days to develop (48 hrs- 73 hrs).
Drug patch test, skin may exposed to 20-30 extracts of substance that cause contact dermatitis.
These include latex, medications, fragrances, hairdyes, metals, resins.
Wear patches on your arm or back for 48 hours.
Drug this time, avoid bathing and activities that cause heavy sweating.
Patches are removed and examine irritated skin at patch site may indicate allergy.
Result
Positive skin test means you may be allergic to particular substance.
Bigger wheals usually indicates greater degree of sensitivity.
Negative skin test means probably aren't allergic to particular allergens.
Skin test carried out for Hypersensitivity Reaction
During allergy skin tests, skin is exposed to suspected allergy -causing substance (allergens) and is then observed for sign of allergic reaction
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Allergy skin tests
Used to diagnose allergic condition, including;
1. Hay fever (allergic rhinitis)
2. Allergic asthma
3. Dermatitis (eczema)
4. Food allergy
5. Penicillin allergy
6. Bee venom allergy
3. Allergy testing By Skin Prick test and skin injection test
Skin prick test;
1. Puncture test
2. Scratch test
Check for immediate allergic reaction.
Test is usually do to identify;
Allergies to pollen
Mold
Dust, mites
Food
In adult test; done on forearm
In children test; done on upper back
Process;
Skin prick testing;
Uses needles that penetrate skin surface.
After cleaning, test site with alcohol
Nurse draw small mark on skin and applied drop of allergen extract next to each mark.
Then uses needle to prick extracts into skin's Surface.
New needle is used for each allergen.
To see if skin is reacting normally two additional substances are scratched into skin surface.
1. Histamine
Cause skin response.
If don't react to histamine, allergy skin test not reveal allergy.
2. Glycerine or saline
In most cases these substances don't cause any reaction.
If react to glycerine or saline, may have sensitive skin.
Monitor to see how skin react to foreign substance.
After 15 minutes after skin pricks; observes your skin for sign for allergic reaction.
If you are allergic to one of substances tested, develop a raised, red, swelling itchy bump (wheal) look like mosquito bite, allergic to specific allergens.
Measure the bump size and record results.
He clean your skin with alcohol to remove mark.
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