You might suffer from environmental allergies but have no idea what’s causing you to sneeze and cough and your eyes to water and itch. You just know that something in the air is making you miserable.
Allergy symptoms result when the body’s immune system reacts to something in the environment that it perceives as a danger. Triggers include pollen, dust and pet dander. Usually, it takes more than one exposure before symptoms begin.
“Your body reacts more the next time you’re exposed to it,” says Brent Senior, MD, an ear, nose and throat (ENT) specialist at UNC Health.
About 1 in 4 adults and 1 in 5 children have seasonal allergies, according to the Centers for Disease Control and Prevention.
If allergy treatments are effective in controlling your symptoms, you don’t necessarily need to know what’s causing them. But sometimes, it’s important to know what you’re allergic to so you can avoid that allergen or prepare for exposure.
“It’s common for people to be allergic to more than one thing,” Dr. Senior says. “That’s where allergy testing can be helpful, to find out what exactly is setting the person off.”
Your Family History
One of the most reliable ways of determining whether you have environmental allergies is by knowing whether other people in your family are allergic.
“If a primary relative has allergies, asthma or eczema, then you have a good chance of having them, too,” says UNC Health ENT physician Charles Ebert Jr., MD, MPH.
If one parent has allergies, Dr. Ebert says, there’s a 50 percent chance the child will have the same allergies. If both parents have the same type of allergies, the child’s chances go up to 75 percent. If neither parent has allergies, the child has a 13 percent chance of developing allergies to something in the environment.
Two types of tests can help determine what is causing your environmental allergy symptoms: skin tests and blood tests.
How Skin Tests Work
Skin tests involve placing a small amount of a suspected allergen on or below the skin to see if a reaction develops, Dr. Senior says.
“We start with minute amounts of the allergen,” he says, “then slowly escalate the amount to see if a person starts reacting at higher doses.”
Skin tests can be done via a skin prick or an intradermal (under the skin) injection.
- With a skin prick test, a drop of solution that contains something you might be allergic to is placed on the skin. Several allergens can be tested at the same time. A doctor or nurse gives a series of scratches or needle pricks to deliver the solution into the skin and watches for reactions, which typically occur within 20 minutes.
- Intradermal testing involves injecting a small amount of an allergen solution just under the skin. This may be used if a particular allergen is suspected but doesn’t show up with a skin prick test. Several allergens can be tested at the same time, and reactions typically occur within 10 minutes, before the test is finished.
How Blood Tests Work
“We do skin tests initially,” says UNC Health allergy nurse Lisa Licht, RN. But in some cases, doctors need additional information from a blood test.
Environmental allergen reactions can be identified in the blood, as the body produces antibodies to fight off something it thinks is harmful. Blood tests are used to look for those antibodies, called immunoglobulin E.
Blood tests may be done if a person takes certain medications that interfere with skin prick test results. These medicines include beta blockers (for heart and blood pressure treatments), antihistamines, antidepressant and anti-anxiety medicines, and acid-reducing medicines, which contain a form of antihistamine.
A healthcare provider draws a small amount of blood to be tested. Results come back in a few days to a week or more.
What Happens After Testing
When you know what you are allergic to, you’re in a better position to avoid the allergen or take precautions before a potential exposure.
If your allergies are seasonal, Dr. Senior says, start treating them weeks before the allergens arrive.
If you are visiting someone with a pet that you’re allergic to, take an antihistamine before you go. If it turns out you are allergic to your own pet, you have options, says UNC Health certified medical assistant Loytoa Torain.
“People have a big fear that they’ll have to get rid of their furry babies,” Torain says. “We tell them that immunotherapy can help desensitize them, and antihistamines can help.”
If you want to know what’s causing your allergy symptoms, talk to a doctor. Need a doctor? Find one near you.