Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Allergies Health Center

Font Size

Allergy Terms

Adenoids: Glands or lymphoid tissue in the upper part of the throat behind the nose.

Adenoidectomy: The surgical removal of adenoids which may help prevent blockage of the nasal passageways and Eustachian tubes. This may help to reduce recurrent sinus and ear infections, among other conditions. This is usually done as an outpatient procedure under general anesthesia.

Recommended Related to Allergies

Fall Allergies and Sinusitis

Autumn has arrived, and you don’t feel so good. You can’t stop sneezing and sniffling. The return of cool weather leaves you feeling not invigorated but miserable. What’s going on? You may be suffering from pollen allergy, a.k.a. allergic rhinitis or hay fever. Thirty million Americans do, and symptoms typically flare in fall. Like all allergies, hay fever stems from a glitch in the immune system. Instead of attacking harmful foreign substances such as bacteria and viruses, it tries to neutralize...

Read the Fall Allergies and Sinusitis article > >

Allergen: A protein substance that triggers an allergic reaction in an individual who is sensitized.

Allergic rhinitis: See Hay fever.

Allergy: An exaggerated response to a substance or condition produced by the release of histamine or histamine-like substances in affected cells in the body.

Allergy index: Measure of allergy sufferers who are affected by pollen in your region. Since some types of pollen may be more likely to cause allergies than others, a high allergy index does not necessarily correspond to a high pollen count.

Allergy shots: See Immunotherapy.

Anaphylaxis: Severe, life-threatening allergic response that may include lowered blood pressure, swelling, and hives.

Angioedema: Swelling similar to urticaria (hives), but the swelling occurs beneath the skin instead of on the surface. Angioedema is characterized by deep swelling around the eyes and lips and sometimes of the hands and feet.

Antibodies: Specialized proteins produced by lymphoid cells (B cells) that circulate in the blood. Antibodies seek and attach to foreign proteins, microorganisms, or toxins in order to neutralize them. They are part of the immune system.

Antigen: A substance, usually a protein, which the body perceives as foreign.

Antihistamine: Medication that prevents symptoms of congestion, sneezing and itchy, runny nose by blocking histamine receptors.

Anti-inflammatory: Type of medication that reduces swelling and inflammation.

Asthma: A disease of the branches of the windpipe (bronchial tubes) that carry air in and out of the lungs. Asthma causes the airways to narrow, the lining of the airways to swell, and the cells that line the airways to produce more mucus. These changes make breathing difficult and cause a feeling of not getting enough air into the lungs.

Bronchodilators: Medications used to relax the muscle bands that tighten around the airways during an asthma episode. Bronchodilators also help clear mucus from the lungs.

1 | 2 | 3 | 4

Today on WebMD

man blowing nose
Make these tweaks to your diet, home, and lifestyle.
Allergy capsule
Breathe easier with these products.
cat on couch
Live in harmony with your cat or dog.
Woman sneezing with tissue in meadow
Which ones affect you?

blowing nose
woman with sore throat
lone star tick
Woman blowing nose

Send yourself a link to download the app.

Loading ...

Please wait...

This feature is temporarily unavailable. Please try again later.


Now check your email account on your mobile phone to download your new app.

cat lying on shelf
Allergy prick test
Man sneezing into tissue
Woman holding feather duster up to face, twitching