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Allergy tests
Skin prick tests are used by most medically trained allergy specialists to confirm allergies. The tests are usually carried out using standardised extracts of common allergens. Small drops of extract are placed on the skin (usually the inner forearm). A metal lancet is used to prick the skin lightly through the drop. The tests are read after 15-20 minutes.
If there is a reaction, the skin itches and a weal (similar to a nettle sting bump) appears within a few minutes. This will normally be between 1-6mm size and last for 1-2 hours. The itch settles most quickly. As only a tiny amount of allergen is pricked into the skin, the tests are safe. Results are available immediately.
Patch Tests - If you suspect a skin reaction to skin preparations, chemicals or metals in direct skin contact then patch testing is more useful than skin prick tests or blood tests. These tests require dermatological expertise and it would be best to see a skin specialist rather than an allergy specialist. If you suspect food or dust mite allergy as a cause of skin rashes, then seeing an allergy specialist may help you.
Challenge Tests - Very occasionally it is necessary to have a challenge test with a suspect food or drug. These tests are performed using very cautious dosing regimes under close supervision in a hospital laboratory.
Unconventional allergy tests - A report of the Royal College of Physicians has ruled that neutralisation-provocation tests, leucocytotoxic tests, hair analysis, Vega testing, applied kinesiology and the auricular cardiac reflex method have no place in the diagnosis of allergy.
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