What is allergy skin testing?
Allergy skin testing helps diagnose allergies. Allergy skin testing can identify 10 to 50 specific substances, called allergens, which cause allergy symptoms in children and adults. Common allergens include foods, latex, medications, insect stings, and environmental particles, such as dust, pollen and mold.
An allergist will interpret your allergy skin testing results in relation to your medical history, physical exam, and other tests. An allergist, also known as an allergist-immunologist, has the specialized skills and experience needed to read allergy skin testing results properly.
Allergy skin testing is only one method used to diagnose allergies. You may have less invasive testing options. Consider getting a second opinion about all of your testing choices before having allergy skin testing.
Types of allergy skin testing
The types of allergy skin testing include:
Prick/puncture/scratch skin test involves applying a diluted allergen with a small prick, puncture, or scratch to the skin’s surface.
Intradermal test involves injecting a diluted allergen below the skin surface using a tiny needle. Doctors sometimes use intradermal tests after a negative scratch skin test to collect more information about possible allergens.
Other procedures that may be performed
Your doctor may combine allergy skin testing with the following tests and procedures to diagnose allergies:
Allergy symptom log to record when you have symptoms, how long they last, what you were doing at the time, what medications you took, and how the medication worked.
Elimination diet to eliminate certain foods one by one to see if certain foods cause allergy symptoms
Food log to record the foods you eat and if they cause allergy symptoms
RAST (radioallergosorbent test), a blood test to help identify the substances that cause your symptoms
Why is allergy skin testing used?
Your doctor may recommend allergy skin testing to diagnose the cause of allergy symptoms from the following types of allergens:
Environmental allergens including mold, dust mites, pet dander, or tree pollen
Food allergens including peanuts, milk, wheat and eggs
Insect venom
Latex
Medications including penicillin
Ask your doctor about all of your testing options and consider getting a second opinion before deciding on allergy skin testing.
Who performs allergy skin testing?
An allergist or pediatric allergist performs or supervises allergy skin testing. Sometimes, a specially trained registered nurse (RN) performs the testing.
Allergists, also known as allergist-immunologists, specialize in caring for people with allergies, asthma, and other diseases of the immune system. Pediatric allergists specialize in caring for children from infancy though adolescence with the same diseases and conditions. Allergists have advanced training and education to read allergy skin tests properly.
How is allergy skin testing performed?
Your allergy skin testing will be performed in a doctor’s office or clinic. A prick/puncture/scratch skin test tests for 10 to 50 allergens. It generally involves these steps:
Your doctor completes a medical history and physical exam and asks you about your allergy symptoms.
You may keep an allergy log to help determine the most likely allergens. A log can include recording when you have symptoms, how long they last, what you were doing at the time, what medications you took, and how the medication worked.
You may participate in an elimination diet if your doctor suspects food allergies. This diet eliminates foods one by one to see if a certain food causes symptoms. Your doctor will evaluate the above steps to decide if you are a good candidate for allergy skin testing.
Your doctor will also ensure that allergy skin testing does not put you at risk for a serious reaction, such as anaphylaxis or an asthma attack.
Your doctor or nurse will apply the allergens with a tiny prick or scratch on the surface of your skin. The forearm is the usual site in adults. The back is the usual site in children. This process takes five to 10 minutes.
Your doctor will examine your skin after about 15 to 20 minutes. You may be allergic to a particular allergen if a small red lump appears at any of the allergen prick or scratch sites on your skin.
Your doctor will interpret the results in relation to your medical history, physical exam, and other tests.
Your doctor may recommend an intradermal test if your prick/puncture/scratch skin test results are normal or unclear. An intradermal test generally involves these steps:
Your doctor or nurse will inject a diluted allergen below the skin on the arm or forearm using a tiny needle. Your doctor can test several allergens at the same time.
Your doctor will examine your skin after about 15 to 20 minutes. You may be allergic to a particular allergen if a small red lump appears at any of the allergen sites on your skin.
Your doctor will interpret the results in relation to your medical history, physical exam, and other tests.
Sometimes a reaction does not appear until several hours after allergy skin testing. Call your doctor right away about any delayed reactions.
Will I feel pain with allergy skin testing?
Your comfort and relaxation is important to both you and your care team. You may feel a brief pinch or prick during the test. Take a few long, deep breaths to help yourself relax. Tell your doctor if the pain does not pass quickly.
What are the risks and potential complications of allergy skin testing?
Allergy skin testing involves risks and potential complications. Complications may become serious and life threatening in rare cases. Complications can develop during or after the test and include:
Triggering of allergy symptoms including mild itching and swelling of the skin. A severe reaction, such as anaphylaxis or an asthma attack, can occur but is rare. Your allergist is trained and prepared to treat an allergic reaction immediately.
Misreading of test results, which can result in improper allergy treatment. The risk of this is much lower when an allergist with training and experience in allergy skin testing performs the test.
Reducing your risk of complications
You can reduce the risk of some complications by following your treatment plan and:
Following activity, dietary and lifestyle restrictions and recommendations
Informing your doctor if you are nursing or if there is any possibility of pregnancy
Keeping all scheduled appointments
Notifying your doctor immediately of any concerns after your allergy skin testing, such as itching and swelling. Call 911 immediately for shortness of breath, mouth or facial swelling, or difficulty talking or swallowing after skin allergy testing.
Taking your medications exactly as directed. Your doctor may tell you not to take antihistamines and other allergy medications before your allergy skin testing because they can interfere with test results.
- Telling all members of your care team any allergies you have or suspect
How do I prepare for my allergy skin testing?
You are a very important member of your own healthcare team. The steps you take before allergy skin testing can improve your comfort and help your doctor get the most accurate test results.
You can prepare yourself for allergy skin testing by:
Answering all questions about your medical history and medications. This includes prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.
Getting other testing as directed. Testing will vary depending on your age, health, and medical history.
Taking or stopping medications exactly as directed. Your doctor may tell you not to take antihistamines and other allergy medications before your allergy skin testing because they can interfere with test results.
Questions to ask your doctor
Having allergy skin testing can be stressful. It is common for patients to forget some of their questions during a doctor’s office visit. You may also think of other questions after your appointment. Contact your doctor with concerns and questions before allergy skin testing and between appointments.
It is also a good idea to bring a list of questions to your appointment. Questions can include:
Why do I need allergy skin testing? Are there any other options for diagnosing my symptoms?
How long will the procedure take? When can I go home?
What restrictions will I have after the procedure?
How should I take my medications?
When will I get the results of any tests?
When should I follow-up with you?
How should I contact you? Ask for numbers to call during and after regular hours.
What can I expect after my allergy skin testing?
Knowing what to expect after allergy skin testing can help you get back to your everyday life as soon as possible.
How will I feel after allergy skin testing?
A positive reaction can cause irritated, itchy and red bumps, similar to mosquito bites. Reactions usually go away in minutes to a few hours. Tell your doctor if you are uncomfortable or have allergy symptoms or other new or unusual symptoms.
When can I go home?
You will likely go home right after allergy skin testing.
When should I call my doctor?
It is important to keep your follow-up appointments after allergy skin testing. Call your doctor fir questions and concerns between appointments.
Most allergy reactions occur while you are still at the doctor’s office for your test. Sometimes a delayed reaction can occur. Call your doctor right away if you have itching, swelling, or bumps on the skin testing area after going home. Call 911 immediately for shortness of breath, mouth or facial swelling, or difficulty talking or swallowing after skin allergy testing.
