Allergy Skin Test
Reviewed
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.
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.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- 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.