What is a skin prick test?
A skin prick test, or SPT, is a clinic-based way to check whether the skin reacts to selected allergen extracts. A clinician places small drops on the skin, usually the forearm or back, then gently pricks the surface at each drop. The test is designed to help evaluate sensitisation, not to diagnose an allergy by itself.
How long does it take?
Skin responses are usually observed and measured after approximately 15–20 minutes. The clinician records any raised area, sometimes called a wheal, and interprets it alongside control tests. Allow time for a clinical discussion as well as the test itself.
What can be tested?
The selection depends on your history. Depending on your symptoms and exposure, a doctor may choose dust mites, pollen, mould, pet dander, or selected food extracts. A broad positive panel without matching symptoms can lead to incorrect assumptions, so targeted selection matters.
How do I prepare for SPT?
- Share details of previous severe reactions, asthma, eczema and current medicines with the testing clinic.
- Ask the clinician whether any medicine could affect the test and follow their specific preparation instructions. Do not stop medication without advice.
- Describe when symptoms occur and what you suspect triggers them; a symptom diary can help.
Does a positive SPT mean I definitely have an allergy?
No. A positive response indicates sensitisation to the tested substance. It does not automatically mean that the substance causes symptoms in everyday life, nor does it establish severity. Your doctor considers the size of the response, your symptoms, exposures and medical history before deciding what it means.
What comes next?
Your clinician may advise exposure measures, symptom management, or further evaluation. If a relevant allergy is confirmed, a doctor can discuss whether an option such as sublingual immunotherapy is suitable. Read the broader allergy testing guide to compare SPT with specific IgE blood testing.
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