Allergy Skin Test
Reviewed
Also called: Type 1 hypersensitivity skin test, Hypersensitivity test, Allergy scratch test, Allergy patch test, Intradermal test, Prick test or puncture test
An allergy skin test helps find out what is causing your allergic reaction by exposing your skin to allergy-causing substances (allergens). It is used to diagnose certain allergies.
Specimen: Not applicable; this is a procedure involving skin exposure to allergens.
Urgent safety information
If you are at risk for anaphylactic shock, you may need to carry an emergency epinephrine auto-injector. If you experience symptoms of anaphylactic shock after the test, inject epinephrine and call 911 immediately. For patch tests, if you feel intense itching or pain under the patches at home, remove them and call your provider.
Why this test may be ordered
- To diagnose certain allergies when you have symptoms such as stuffy or runny nose, sneezing, itchy watery eyes, hives, diarrhea, vomiting, shortness of breath, coughing, or wheezing.
- To identify which substances (allergens) are causing your allergic reaction so your provider can plan treatment.
Preparation and collection
You may need to stop taking certain medicines, such as antihistamines and some antidepressants, before the test. Your provider will tell you which to avoid and for how long. For a patch test, avoid heavy sun exposure and tanning for at least two weeks before the test.
Performed by an allergist or dermatologist in an office setting.
There is very little risk. The test itself is not painful. The most common side effect is red, itchy skin at the test areas. In very rare cases, anaphylactic shock can occur. For patch tests, intense itching or pain under the patches may require removal and a call to your provider.
Understanding results
Test results are reported as positive or negative based on the presence and size of red bumps (wheals) or swelling at the test sites.
- Positive: You are probably allergic to the substances that caused a reaction. Limitation: A positive result is not a confirmed diagnosis. Your provider will interpret it along with your symptoms and history. Next step: Your provider will likely recommend treatment, which may include avoiding the allergen, medications, or lifestyle changes.
- Negative: You are probably not allergic to the tested substances. Limitation: A negative result does not guarantee you are not allergic. Your provider may recommend additional testing if your symptoms suggest an allergy. Next step: Your provider may consider other causes for your symptoms or perform further testing, such as an intradermal test or blood test.
- Common side effect is red, itchy skin at test areas.
- Very rarely, an allergy skin test can cause anaphylactic shock, a life-threatening reaction. Therefore, tests are only done where emergency equipment is available.
- A positive result indicates a higher likelihood of allergy but is not a confirmed diagnosis; your provider will consider your symptoms and history.
- A negative result indicates a lower likelihood of allergy but does not completely rule out an allergy.
- For patch tests, if you feel intense itching or pain under the patches at home, remove them and call your provider.
What to do next
Your provider will use your results, symptoms, and medical history to create a treatment plan. If you are at risk for anaphylactic shock, you may need to carry an epinephrine auto-injector and know how to use it.
- What is it used for?
- Why do I need an allergy skin test?
- What happens during an allergy skin test?
- Will I need to do anything to prepare for the test?
- Are there any risks to the test? What do the results mean?