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Allergy Testing
Allergy testing helps find out what you are allergic to, using a skin prick test or a blood test. It guides how to avoid triggers and manage reactions.
Quick answer
Allergy Testing: what it is and what the results mean
Allergy testing identifies substances (allergens) that trigger an allergic reaction. The two main methods are a skin prick test, where tiny amounts of allergens are placed on the skin, and a blood test that measures allergy antibodies.
- Why it is done: It is used to help confirm suspected allergies — such as to pollen, foods, pets, dust mites or medicines — and to guide avoidance, treatment and, in some cases, specialist therapies.
- Understanding results: A positive result suggests sensitivity to that allergen, but must be interpreted alongside your history — reactions in real life matter more than the test alone, as some positive results do not cause symptoms.
What it is
Allergy testing identifies substances (allergens) that trigger an allergic reaction. The two main methods are a skin prick test, where tiny amounts of allergens are placed on the skin, and a blood test that measures allergy antibodies.
Why it is done
It is used to help confirm suspected allergies — such as to pollen, foods, pets, dust mites or medicines — and to guide avoidance, treatment and, in some cases, specialist therapies.
What to expect
For a skin prick test, drops of allergen are placed on the forearm and the skin is gently pricked; small itchy bumps appear within about 15 minutes if positive. A blood test simply involves a standard blood sample.
Understanding the results
A positive result suggests sensitivity to that allergen, but must be interpreted alongside your history — reactions in real life matter more than the test alone, as some positive results do not cause symptoms.
Good to know
Risks and limitations
Skin prick testing is generally safe under supervision, with a very small risk of a larger reaction, which is why it is done where help is available. Tests can be positive without causing real-world symptoms, so results always need clinical interpretation.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Allergy Testing: frequently asked questions
Which is better, a skin prick test or a blood test?
Both are useful and the choice depends on your situation — skin prick tests give quick results, while blood tests are used when skin testing is not suitable. A specialist decides which fits best.
Can allergy tests be wrong?
Tests can show sensitivity that does not cause real symptoms, or occasionally miss an allergy. That is why results are always interpreted alongside your history rather than relied on alone.
Related tests
Other other investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- UK National Screening Committee / relevant professional body
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