Top Allergy Terms

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

Adenoidectomy: The surgical removal of adenoids. It can help prevent blocks in your airways and the Eustachian tubes in your ears. This may make you less likely to get frequent sinus and ear infections, among other problems. It’s usually an outpatient procedure under general anesthesia.

Allergen: A substance that triggers an allergic reaction in a person who’s sensitive to it.

Allergic rhinitis: See Hay fever.

Allergy: A severe response to a substance or condition. It happens when your body produces and releases histamine or histamine-like substances.

Allergy index: A measure of people with allergies in your region who are affected by pollen. Since some types of pollen are more likely to cause allergies than others, a high allergy index doesn’t always mean there’s a high pollen count.

Allergy shots: See Immunotherapy.

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


Angioedema: Swelling that’s similar to hives, except it happens under your skin instead of on the surface. You’ll notice a deep swelling around your eyes and lips and sometimes on your hands and feet.

Antibodies: These special proteins seek out, attach to, and zap foreign proteins, microorganisms, or toxins in your blood. They’re part of your immune system.

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

Antihistamine:Medication that prevents symptoms like congestion, sneezing, and itchy, runny nose.

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

Asthma: A disease that affects the branches of your windpipe (bronchial tubes) that carry air in and out of your lungs. Your airways narrow, their linings swell and produce more mucus. All this makes it hard to breathe. You might feel like you aren’t getting enough air into your lungs.

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

Conjunctivitis: Also called pinkeye, it’s an inflammation of the conjunctiva, the tissue that lines the inside of your eyelid.


Dander, animal: Tiny scales shed from animal skin or hair. It floats in the air, settles on surfaces, and makes up much of household dust. Pet dander is a classic cause of allergic reactions.

Decongestant: Medication that shrinks swollen nasal tissues to relieve symptoms like swelling, congestion, and mucus.

Dermatitis: Inflamed skin, either due to an allergic reaction or direct contact with an irritating substance. Symptoms include redness, itching, and sometimes blistering.

Drug allergy: An allergic reaction to a specific medication, like penicillin.

Dust mites: Microscopic insects that live in household dust and are common allergens. Dust mites live on dead skin cells. You’ll find them in mattresses, pillows, carpets, curtains, and furniture.

Elimination diet: When you temporarily stop eating certain foods to rule them out as a cause of your allergy symptoms. It could be a permanent change if you have celiac disease or a long-lasting food allergy.

ELISA (enzyme-linked immunosorbent assay): This blood test helps your doctor figure out what causes your allergy symptoms and how sensitive to them you are.


Epinephrine: A form of adrenaline medication used to treat severe allergic reactions, like anaphylactic shock or insect stings. It’s available in a self-injectable form or a doctor can give you a shot.

Food allergy: Your immune system reacts to a specific food that isn’t really a threat to your body.

Hay fever: An allergic reaction to pollen from ragweed, grasses, and other plants whose pollen spreads on the wind.

HEPA: Stands for high-efficiency particulate air (HEPA) filter. A filter, or gadget with this kind of filter, that cleans the air by forcing it through screens containing microscopic pores.

Histamine: A naturally occurring substance that your immune system releases after it’s exposed to an allergen. Histamine is responsible for many of the symptoms of an allergy.

Hives: See Urticaria.

Hydrofluoroalkaneinhaler (HFA): This small aerosol canister in a plastic container that releases a burst of medication when you press down from the top. Many asthma drugs are taken using an HFA. HFAs were formerly referred to as metered dose inhalers of MDIs.


Hypoallergenic: Products made to contain the fewest possible allergens.

Immune system: The body's main defense system. It protects us from infections and foreign substances.

Immunotherapy: It’s a way to gradually increase your tolerance to the things that cause allergy symptoms (allergens). It works best for people who have symptoms more than 3 months out of the year. You can take it as shots, oral tablets, or drops.

Latex: Also known as rubber or natural latex, this milky fluid comes from the rubber tree. It’s used in a number of everyday products, like rubber gloves and rubber bands.

Latex allergy: An allergy that shows up after you come into contact with latex.

Mast cell: A type of white blood cell that’s part of an allergic reaction. These cells release chemicals like histamine.

Metered dose inhaler (MDI):  See Hydrofluoroalkane inhaler.

Mold: This common allergy trigger is a parasitic, microscopic fungi that floats in the air like pollen. You can find it in damp areas, like basements or bathrooms, as well as in grass, leaf piles, hay, mulch, or under mushrooms.


Mold count: See Pollen and mold counts.

Myringotomy: An outpatient procedure in which your doctor inserts small metal or plastic tubes through your eardrum to equalize pressure between the middle and outer ear.

Nasal endoscopy: A test that lets your doctor see in your nasal cavity. It can help him spot polyps or other problems.

Nasal sprays: Medication used to prevent or treat nasal symptoms. Some are prescription-only, others you can get over-the-counter. They come in decongestant, antihistamine, corticosteroid, or salt-water solution form. A mast cell (see above) stabilizer form is also available.

Otitis media: This infection affects the middle ear (the space behind your eardrum). It can be bacterial or viral.

Otolaryngologist: A doctor who specializes in diagnosing and treating a variety of disorders of the ear, nose, and throat.

Otoscope: This lighted tool lets the doctor see far down into your outer ear canal.

Pneumatic otoscope: This tool blows a puff of air into your ear canal to test eardrum movement.


Pollen: A fine, powdery substance released by plants.

Pollen and mold counts: A measure of the amount of allergens in the air. The counts are usually reported for mold spores and three types of pollen: grasses, trees, and weeds. The count is reported as grains per cubic meter of air and is translated into a level: absent, low, medium, or high.

Pulmonary function test: This test measures how well your lungs take in air and exhale air. Also checks how well your lungs transfer oxygen into the blood.

RAST (radioallergosorbent test): This blood test shows how your immune system responds to a specific allergen. It checks your blood for immunoglobulin E (IgE), which cause allergies.

Skin prick test: A doctor places a possible allergen on your skin, then pricks or scratches the skin under it. This lets the allergen enter your body. If a red, raised itchy area (called a wheal) shows up, you’re allergic. This is called a positive reaction.


Sinusitis: An inflammation of the sinuses usually caused by a secondary bacterial infetion. Acute sinusitis is a sudden onset of symptoms. Your doctor may treat it with antibiotics and decongestants. Chronic sinusitis is irritation or an infection that lasts several weeks.

Tympanometry: This test uses sound and air pressure to check for problems with your middle ear.

Urticaria (hives): These itchy, swollen, red bumps or patches pop up on your skin when you’re exposed to an allergen. They can appear anywhere on your body including the face, lips, tongue, throat, or ears. Hives vary in size and can last for minutes to days.

WebMD Medical Reference Reviewed by Dan Brennan, MD on July 19, 2019



American Academy of Allergy, Asthma and Immunology. 

Mayo Clinic.

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