How Are Allergies Diagnosed and Treated?

Your doctor will ask you what allergens you might have come in contact with. He’ll also ask for your personal and family medical history to figure out what’s causing your troubles.

He may run tests to rule out other health problems that might look like allergic reactions. He could ask you to keep track of potential triggers and your reactions for a week to help him diagnose you. After this, he’ll choose a testing method.

The most common test for respiratory, penicillin, insect sting, skin, and food allergies is a skin prick or scratch test. The doctor scratches a small amount of the allergen into your skin and watches for swelling, itchiness, and redness in that area. Other tests look for signs in the blood that are linked to allergies.

Results can differ from one test or one lab to another. Your doctor can help figure out which tests are best for you and help you understand what the results mean.

How Are Allergies Treated?

The best thing to do is avoid the things that trigger your symptoms in the first place, but that isn’t always easy.

Nasal steroids, available over-the-counter or by prescription, are often the first drug recommended for nasal allergies (hay fever). Your doctor might prescribe anti-inflammatory steroid drugs, like prednisone, for severe symptoms.

Antihistamines, available over-the-counter, block the effects of chemicals your body makes that cause the allergic reactions.

An epinephrine shot is for an emergency, when an allergic reaction becomes life-threatening. It works quickly to bring up low blood pressure and open narrowed airways.

Allergy shots -- also called immunotherapy or allergy desensitization therapy -- may help ease attacks. You’ll get small amounts of things that trigger your symptoms, like pollen. It’ll help your body get used to that allergen. It may take a year before it really starts to work.

What Works Best for Specific Allergies?

Skin conditions: Atopic and contact dermatitis can be treated with a variety of anti-inflammatory steroids either applied to your skin or taken by mouth. Mild cases of hives and angioedema, a swelling that goes with them, may not need treatment. But severe cases require antihistamines, or steroid pills. Stomach medicines that have some antihistamine effect, like ranitidine, may also help.

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Respiratory allergies: Doctors treat allergic rhinitis, or hay fever, with corticosteroid sprays. They work well over the long term, but you have to take them regularly. Two kinds, triamcinolone and fluticasone, are available over the counter.

Pills like over-the-counter loratadine work, but might make you drowsy. You can also take a once-a-day med called a leukotriene receptor antagonist.

Allergy shots work well after the first year. Another treatment that gives you a bit of the allergen is available in tablets that dissolve under your tongue.

Food allergies : Your best bet is to stay away from the problem food. If your reaction is mild -- the food makes you itch or makes your eyes water -- antihistamines or topical creams might be all you need. If you’re highly allergic and likely to go into anaphylactic shock, your doctor will prescribe an emergency kit and show you how to use it. Keep two with you at all times if your doctor prescribes them. It contains a preloaded epinephrine shot. If you think you're having an emergency, don’t wait to take it. Then call 911.

Drug allergies: If you’re allergic to medications, wear a MedicAlert bracelet. Always discuss this allergy with doctors when they give you a new prescription. Some skin rashes caused by drug allergies respond to antihistamines. Others require steroids you take by mouth or rub onto your skin. An allergy specialist can help you get used to some antibiotics.

Insect sting allergies : Again, the best thing is to do what you can to avoid getting stung. But allergy shots can make a reaction less severe. If you’re highly allergic and anaphylaxis is a possibility, your doctor will prescribe an emergency kit with an epinephrine shot. Carry two with you at all times if your doctor prescribes them. Use one in case of an emergency, then call 911.

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on October 21, 2015

Sources

SOURCES: 

Asthma and Allergy Foundation of America: "Allergy Overview."

American Academy of Allergy, Asthma and Immunology: "Allergies."

The Food Allergy and Anaphylaxis Network: "About Food Allergy." 

WebMD Medical Reference: "Allergies Health Center." 

MedlinePlus Medical Encyclopedia: "Allergy."

News release, FDA.

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