What Is a Skin Allergy Test? A Guide to the Procedure and Process

Written by Kendall K. Morgan
Medically Reviewed by Poonam Sachdev on June 09, 2025
7 min read

Skin testing is one way your doctor can find out what you're allergic to so you can avoid an allergic reaction. 

These tests use extracts (a concentrated liquid form) of common allergens such as pollen, mold, dust mites, animal dander, bee stings, and various foods. Once those get into your skin, they could trigger a rash. Your skin will get irritated and may itch, like a mosquito bite.

Skin allergy tests can look for a variety of possible allergy triggers in different categories, such as:

  • Airborne
  • Environmental
  • Food-related
  • Related to animals, including insects
  • Medications

Skin testing works because when you have an allergy, your immune system makes antibodies and sets off chemicals to fight off the trigger. That reaction causes the redness and rash that tells your doctor you're allergic to something.

Your doctor might suggest you get a skin allergy test if you've had a reaction that suggests you're allergic to something. Allergy symptoms may include:

  • Sneezing
  • Runny nose
  • Itchiness in or around your eyes, mouth, and nose
  • Swelling of your lips or tongue
  • Itchy, red skin or a rash
  • Hives
  • Coughing or wheezing
  • Trouble breathing
  • Headaches
  • Nausea or vomiting
  • Asthma attacks
  • Severe allergic reaction (anaphylaxis)

If you've had any of these signs, it could mean you've got one or more allergies, and your doctor may test you to see if they can figure out what's causing it. Skin testing is one way they can do this.

"I tell my patients that the benefits of getting tested are that we can develop a targeted treatment plan, work to prevent severe reactions by knowing which substances to avoid, and how to prepare for emergencies," says Sonali Majmudar, MD, an allergist at Majmudar Allergy in Hoffman Estates and Algonquin, IL, who is a spokesperson for the American College of Allergy, Asthma, & Immunology. "If your allergy symptoms are affecting your daily activities, persist without an explanation, or cannot be controlled with over-the-counter medications, you should consider allergy skin testing."

It's especially important to get tested if you've had a severe allergic reaction. Anaphylaxis can happen fast and leave you struggling or unable to breathe. If you don't get help, anaphylaxis is life-threatening.

Your doctor may use different types of skin allergy tests. They all work in about the same way. The difference is in how the allergen is applied to or injected into your skin.

Scratch test 

Scratch tests are sometimes called skin prick tests. This is the most common type. Your doctor will put a small amount of suspected substances on your arm or back. They'll gently prick the skin so the allergen can get in.

Patch test

Your doctor will put patches with possible allergy triggers on them. Usually, you'll have them on your back. You'll need to keep them there for a couple of days to see if you have a reaction. This type of test can look for causes of contact dermatitis.

Skin injection test

Your doctor might call this an intradermal test. Instead of putting an allergen on the surface of your skin, your doctor will inject a small amount just under your skin.

"The first-line diagnostic test generally is a skin prick test," Majmudar says. "In cases where the prick test is negative, but an allergy is still suspected, you can perform an intradermal test."

"It’s a quick and easy process," Majmudar says.

The steps vary depending on what type of test you're having. If you're having a scratch or skin prick test, your doctor or nurse will look at the skin on your forearm or back and clean it with alcohol. They'll mark and label areas on your skin with a pen. Then, they'll place small drops of potential allergens on each of those spots. Next, they'll scratch the outer layer of your skin to let the allergen in. It's not a shot, and it won't make you bleed. Usually, it doesn't hurt.

For an intradermal test, the doctor or nurse will inject a small amount of allergen just under your skin.

Your doctor will also have two controls to make sure the test is working and that you have normal immune responses. One is histamine, which your body should react to. It tells your doctor that you have normal histamine reactions. The other is saline (salt water), which shouldn't cause any reaction.

Plan for an hour-long appointment. The pricking part of scratch and intradermal tests takes about 5-10 minutes. Then, you'll wait about 15 minutes to see how your skin reacts.

Patch tests require two visits to your doctor and take more time. You'll have to wear a patch for about 48 hours in case you have a delayed reaction to the allergen.

After a skin prick or intradermal test, your doctor will be able to read its results, usually within about 20 minutes. They'll look at your skin to see how it reacted to each allergen. They'll measure your reaction and record the results to diagnose any allergies you have.

Positive skin allergy test

You'll get a red, raised bump on your skin. It's also called a wheal. This bump shows that you reacted to the allergen placed in that spot. The size of it can also help your doctor figure out how allergic you are. A bigger bump means you're more allergic to that substance.

Negative skin allergy test

Your skin won't show any reaction. It should look similar to the control spot where your doctor put saline.

"We ask patients to do three things in preparation for allergy skin tests," Majmudar says. "Stop all antihistamines, including both prescription and over-the-counter, at least three to seven days before the test, as they can interfere with results. Do not use lotions, creams, or moisturizers on the test area. Wear appropriate clothing for easy access to testing on the day of your appointment."

Tell your doctor about all medicines you're taking, including over-the-counter products. Some drugs can affect the results, so your doctor will give you a list of medicines to avoid before the test. Medicines that may affect allergy testing results include:

  • Antihistamines
  • Antidepressants
  • Heartburn medicines
  • Asthma medicines

If you can't stop taking a medication, your doctor or nurse may do a separate test to find out if that drug will affect your results.

A skin test may be mildly irritating, but most people say it doesn't hurt. Although you're coming into contact with things you could be allergic to, they're in very small amounts.

Whole-body reactions to allergy skin tests are rare, but let your doctor know right away if you have:

The doctor or nurse will clean any extracts and ink marks off your skin with alcohol. You may need to use a mild cortisone cream to ease itching.

If you get a patch test, you'll go home with bandages on your skin. Don't get these areas wet — no baths or swimming. When you go back to the doctor in a couple of days, they'll take another look at your skin.

Your doctor or allergist will use the results of your test to come up with a treatment plan for you. 

If your results weren't clear, your doctor may want to do more checks. Some people need blood tests or "challenge testing," in which you breathe in or take by mouth small amounts of the allergy trigger.

Once you know what you're allergic to, you can take steps to protect yourself. For instance, if dust mites are the problem, you can wrap your mattress in an allergy-proof cover to keep them out.

Your doctor may suggest medicine to control your symptoms. Allergy shots can also help, although they take much longer to work.

You may get a skin allergy test if you're having ongoing or worrisome symptoms that you and your doctor think may be caused by one or more allergies. The test involves putting substances on or in your skin to see if they cause a reaction. Skin allergy tests usually don't hurt and can give you results the same day.

Is allergy skin testing covered by insurance?

It depends on what kind of health insurance you have, your deductible, and other factors. It's always a good idea to check with your insurance to see what's covered. 

How can I test my skin for allergies at home?

You can buy kits that say you can use them to test for allergies at home. The results of these tests aren't reliable, so it's better to see your doctor for skin allergy testing.

How painful is an allergy skin test?

You might feel a prick, and your skin may get itchy. Everyone is different, but most people don't find skin allergy testing painful.

How accurate is skin allergy testing?

Skin allergy testing is good at figuring out what you're allergic to. It is limited to the substances your doctor uses, so a negative result doesn't mean you aren't allergic to something else. No test is 100% accurate. It's also important to have someone who knows how to read the results. If the first test doesn't figure out what's causing allergy symptoms and an allergy is still suspected, you may need to get more tests.