Allergy Treatments

What You Need to Know About Allergy Testing

A doctor's gloved hands performing a skin allergy test on a person in a plaid shirt

Some allergy sufferers are glued to their pollen count apps. Others greet the changing of the seasons with a sense of dread, just waiting for the day their symptoms strike.

If you don’t know what you’re allergic to, you may feel out of control when it comes to your health. If that’s you, you’ve probably considered getting an allergy test at least once or twice. But how exactly does allergy testing work, and will it even help you manage your symptoms?

What exactly is an allergy test?

An allergy test is a diagnostic tool doctors use to determine if your immune system overreacts to certain substances (which are typically called allergens). Your doctor can help you decide which of the three main tests are right for you.

Skin test

Skin testing is the most common method of allergy testing and usually the type allergists prefer, since it gives the fastest and most accurate results.

If the idea of intentionally exposing yourself to your triggers has you running for the hills, don’t panic: What you’ll experience in a skin test is a pale imitation of a real allergic reaction. You’ll be exposed to a very small amount of the allergen under a doctor’s watchful eye, and most symptoms provoked by the test (like the itchiness) clear up in an hour or two. More severe reactions are possible, but they’re pretty rare.

There are a few different ways to perform this test:

  • In a skin prick or scratch test, your doctor puts a drop of a watery solution containing the possible allergen on your skin (often on your forearm or back). Then, they’ll prick or scratch the spot so the allergen can enter your body. If a red bump appears on your skin within about 15–20 minutes, it’s likely you’re allergic to the substance.
  • In intradermal testing, a small amount of the allergen is injected under the skin using a needle. Since this is a little more uncomfortable, doctors will usually only do it if a skin prick test was inconclusive, or to test for a few specific allergens like insect stings or penicillin.
  • And for skin allergies where symptoms don’t show up for a couple days after contact (think cosmetics, latex, or jewelry allergies), your doctor will do a patch test, where a patch containing the suspected allergen is left on your back for a full day or two to look for a reaction.

Blood test

Your doctor may suggest a blood test instead of a skin test if:

  • you’re taking a medication that could interfere with a skin test, like antihistamines or tricyclic antidepressants
  • you have a skin condition that could influence the results of the skin test
  • the allergen they want to test for isn’t available in a solution that can be used in skin tests
  • the allergy is so severe that your doctor doesn’t want the triggering substance to touch your skin at all

In this test, your doctor will draw blood from your arm and send it to a laboratory to look for the presence of specific antibodies. It’s possible your antibody levels may be elevated for other reasons, though, so blood testing doesn’t provide as definitive of an answer as skin testing.

Provocation test

In a provocation test, your doctor tries to provoke an allergic reaction by mimicking the situation you would encounter in real life. This type of test has a higher risk of severe allergic reaction, so it’s only done as a last resort if other testing methods are inconclusive.

What about at-home allergy tests?

At-home allergy tests are typically blood tests, so they’re not as reliable as skin tests and have the possibility of false positives. If you don’t have access to a doctor who can perform an in-person allergy test for you, though, they could be your best option to get the information you need to start feeling better.

If you do want to take an at-home allergy test, look for one that:

  • asks for a blood sample rather than a hair sample. Hair tests are not a reliable way to diagnose allergies.
  • measures immunoglobulin E (IgE) antibodies rather than immunoglobulin G (IgG) antibodies. IgG measures food intolerances but not true allergies.
  • includes some interpretation of the results rather than just a list of “positives” and “negatives” to help you understand when elevated antibody levels may not signal an actual allergy.

Even if you do go ahead with an at-home test, it’s best to consult with a doctor when interpreting the results and to follow up with a more reliable form of testing before making any changes to your daily routine based on the results.

What allergens are tested in an allergy test?

Typically, a doctor will only test for the specific allergens they suspect you may be allergic to based on your history of symptoms and reactions. Those can include:

At-home allergy tests often examine a much wider range of potential allergens, which is part of what makes them prone to false positives. You should always compare your test results to the symptoms you’ve experienced to make sure the results make sense to you.

What does an allergy test feel like?

Meaning, are you going to be itchy, sneezy, and miserable for days like you are after going out on a bad pollen day? Fortunately, an allergy test is a lot less intense than that.

In a skin test, your doctor will prick or scratch your skin a few times, and if you test positive, that one spot becomes red, inflamed, and itchy (like a bug bite). While a little unpleasant, it’s nothing to be afraid of, especially since it will always be done under a doctor’s supervision and typically fades after a few hours. A blood test, on the other hand, just involves pricking your finger or having blood drawn.

How do I prepare for an allergy test?

Tell your doctor about any medications you may be taking, since a few can interfere with the test results. If you typically take antihistamines to manage your symptoms, your doctor may ask you to stop for 3–7 days before the test.

If you want to get better at navigating your allergy triggers in your everyday life, you may find allergy testing helpful, especially if you’ve had trouble pinpointing which environmental allergens set off your symptoms. It’s a lot easier to get proactive about your allergy treatment when you know what sets you off. Regardless of what you’re allergic to, however, many of the treatment options remain the same.

If you’re still searching for relief, Picnic’s quiz can help find the right allergy treatment for your symptoms.

ARTICLE REVIEWED BYAmina H. Abdeldaim, MD MPHPicnic Medical Director
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