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If you feel like you're constantly reacting to some irritant, it's a good idea to find out what's triggering your allergic reaction. Talk with an allergist about what you think usually causes your allergies and schedule a skin or blood test. They can test for 30 to 40 allergens at a time. Learning what you're actually allergic to will help you make lifestyle changes, start medication, or change your diet so can successfully manage your allergies.

[Edit]Steps

[Edit]Doing a Skin Test

Talk with an allergist about testing for specific allergens. If you suspect you're allergic to a certain substance, ask your allergist if they can perform a skin test to make a diagnosis. Skin tests can reveal if you have:^[1]
- Hay fever (allergic rhinitis)
- Allergic asthma
- Dermatitis (eczema)
- Food allergies
- Penicillin allergy
- Bee venom allergy
- Latex allergy
Determine if you need a prick test, injection test, or a patch test. There are different skin tests to diagnose different allergens. Your allergist will work with you to determine which test is right for you. Prick tests are often used to test for a lot of allergens, such as pollen, mold, dander, or food, all at once. If you think you are allergic to venom or penicillin, you should have an injection test. Consider getting a patch test if you think you have contact dermatitis.^[2]
- Patch tests are also good for diagnosing delayed reactions since the test lasts several days.
Avoid taking medications that could interfere with the skin test. Tell your allergist which medications you're currently taking because some medications could prevent your skin from reacting to an allergen. In general, you'll need to stop taking a medication that could interfere about 10 days before the test.^[3]
- You should stop taking prescription or over-the-counter antihistamines, tricyclic antidepressants, certain heartburn medications, and some asthma medications.
Get an injection to test for venom or penicillin allergies. You should test for a penicillin allergy if you had a reaction to in childhood, because half of the people with penicillin allergies lose the allergy five years after the last reaction. It's good to check if you still have the allergy.
- If you're getting an injection test, the nurse will wipe your skin with an alcohol swab to sterilize it. Then, they'll inject a small amount of the allergen into your skin.
- This is a good test if you only want to check for 1 or 2 allergens.
Have a skin test performed to test for lots of allergens at once. The nurse will clean your forearm with an alcohol swab and draw a grid on your forearm. They'll rub a little of an allergen next to each mark they made. Then, they'll prick each allergen with a needle so it gets under your skin.^[4]
- The nurse will use a separate needle to prick each allergen so they don't' contaminate the testing site.
Apply an allergen patch if you're testing for contact dermatitis. If you think you're allergic to something that your skin is coming into contact with, the allergist will fill a rectangular patch with different allergens. They'll attach the patch to your forearm or your back and you'll wear it for 24 to 48 hours. Patch tests look for allergic reactions to:^[5]
- Medications: lidocaine, tetracaine
- Cosmetics: preservatives, fragrances, essential oils
- Jewelry: nickel, cobalt
- Latex: gloves, condoms
Expect slight discomfort where the skin is being tested. Your skin may react to an allergen before the test is over. It might become a little swollen or red. It may develop itchy bumps called wheals. Keep in mind that any of these side effects could last up to a few days.^[6]
- Although it's rare, you could have a severe allergic reaction. This is why it's important to get skin testing done in an office which has access to emergency medication.
Wait 20 to 40 minutes to get the prick or injection test results. You'll be able to wait at the allergist's office to get the results of your test. Your skin test is the most accurate after the allergens have been on your skin for 20 to 30 minutes, although the allergist can read the test for up to 40 minutes total.^[7]
- Your allergist may want to look at your skin at the 20 minute, 30 minute, and 40 minute mark.
Return to the allergist's office to get the results for a patch test. You'll need to go back to the office after the patch has been on your skin for 24 to 48 hours. The allergist will remove the patch and look at your skin for signs of allergic reactions.^[8]
- If the allergist wants to check for delayed allergic reactions, they may want you to come back again 1 to 2 days later. Then, they can check your skin for reactions that have developed over time.
Discuss the results of the skin test with your allergist. Once you've waited for your skin to react, the allergist will look at your skin for redness, swelling, or itchy bumps. Then, you can work with the allergist to determine if you should make lifestyle changes, take medication, or change your diet.^[9]
- If your skin is still feeling uncomfortable after the test, ask if you should take antihistamines.

[Edit]Getting a Blood Test

Ask for a blood test if you have a skin condition and can't do a skin test. Your allergist might recommend a blood test if you have eczema or psoriasis. You also shouldn't have a skin test if the allergist suspects you might have a severe reaction or if you're taking a medication that would interfere with skin testing and you can't stop taking it.^[10]
- These medications include antihistamines, oral steroids, and H2 blocking medications.
Have your blood drawn to test for pollen, medicine, and animal dander allergies. A phlebotomist will draw blood from a vein in your arm and send the sample to a lab. The lab will test for antibodies that are responding to:^[11]
- Pollen
- Mold
- Dust mites
- Animal dander
- Insect stings
- Latex
- Certain medications, such as penicillin or amoxicillin
Expect minor discomfort and minimal side effects. You won't react to the test itself, but you may feel pain in your arm when the needle draws blood. Your surrounding skin might swell a little and feel sore after the draw.^[12]
- If you faint at the sight of blood, you might ask the phlebotomist to tell you when to look away from the needle.
Wait several days or weeks to get the results of the blood test. Since the bloodwork needs to be sent to a lab and analyzed, you won't be able to get the test results at the same appointment when your blood is drawn.
- If you haven't gotten the results back after 1 to 2 weeks, call your allergist and ask about when you can expect the lab results.
Talk with the allergist about your blood test results. Your allergist may talk with you over the phone about the lab work or they'll ask you to come back to their office. If you tested positive for antibodies, it means you are allergic to certain substances and your body is producing antibodies to fight them.^[13]
- If you have a negative result, the allergist will probably tell you that you don't have an allergy.

[Edit]Tips

If you're currently having an allergic reaction to something, your allergist may wait until it clears up before testing you.
You may want to get tested for allergies throughout your life. Some people develop new allergies or outgrow allergies that they've had since childhood.