Allergy Clinical Services

Glossary of Allergy and Asthma Terms

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Passages throughout the respiratory system for inhaling and exhaling air into and out of the lung: the nose, windpipe (trachea) and bronchial tubes. Airways are lined with mucus that traps irritating particles (like dust and smoke) and tiny hairs that sweep up these particles and keep them from being inhaled deeper into the lungs. People with asthma have highly sensitive airways.


Generic name for a class of medicines that are commonly used short-acting bronchodilators for quick relief of symptoms (like wheezing and shortness of breath). They are typically administered by an aerosol metered dose inhaler (MDI) with a spacer. Also available in pill or liquid form (an oral preparation as syrup) or as a liquid for a nebulizer that mixes it into a mist for inhalation. Common brand names are PROVENTIL, VENTOLIN and XOPEREX (levalbuterol). Used on an as-needed basis and not as a preventive or controller medicine.


Any substance that can cause an allergic reaction; typical examples are pollen, dust and pet dander.


A physician trained to diagnose and treat allergic disorders affecting especially the eyes; nose; throat, lungs, skin and intestinal tract; reactions to foods, drugs and insects; and immune deficiency disorders.


Hypersensitivity to certain irritating substances (allergens).


Pockets of tiny air sacs that split off from bronchioles within each lung. Within alveoli, oxygen from inhaled air is absorbed into the bloodstream in exchange for carbon dioxide waste that is exhaled. There are about 300 million alveoli in both lungs.


Medicine that treats allergies by neutralizing histamine which causes itch, mucus production and some swelling in areas where it is released. Examples: BENADRYL, CLARITIN and ZYRTEC.

Anti-inflammatory Medicines

A class of medicines that reduce airway swelling and help prevent asthma flares. These controller medicines are used regularly whether or not a child is experiencing asthma symptoms.


A chronic respiratory disease in which sensitive airways become inflamed, narrow and obstructed. This occurs when muscles surrounding the airways tighten and squeeze them and excessive mucus is produced. Resulting symptoms include shortness of breath, chest tightness, wheezing and coughing.


Bronchus (singular), Bronchi (plural)

The main airways branching off from the trachea (windpipe) to each lung.


Smaller tubes or airways branching off from the bronchi; the lungs have hundreds of thousands of bronchioles.


Medicine that opens up — or dilates — the airways by relaxing the smooth muscles around the airway walls. It can be administered by inhaler or nebulizer and is often used to prevent exercise-induced asthma symptoms when used 15 to 30 minutes before exercise or sports activity.


Squeezing or tightening of the muscles surrounding the airways, obstructing them and making breathing difficult.


Controller Medicines

A class of medicines that provides long-term control of asthma, usually by decreasing airway inflammation and its symptoms. It is given regularly to prevent symptoms and flares and is not used for immediate relief of symptoms or flares.


A class of medicines that decreases inflammation, inhaled corticosteroids (ICS) are considered the most effective controller medicine for people with persistent asthma. Corticosteroids are not for quick-relief of symptoms. Used regularly, they make triggers less likely to cause symptoms but they take several days or weeks to have full effect. They are not the same as anabolic steroids used to build muscle. Topical corticosteroids (like hydrocortisone) are applied to the skin to treat atopic dermatitis (skin inflammation, redness and itching) caused by allergies.



Flakes of skin or dried saliva from animals with fur or feathers. Materials derived from glands in the skin, saliva, urine and blood adhere to the dander flakes; when people with allergies inhale bits of dander, they react to the allergens that the dander carries.

Dry-powder Inhaler (DPI)

A device for delivering inhaled bronchodilator medicines deep into the lungs by the force of a rapid inspiration; it requires a fast, deep breath. DPIs can typically be used by children over age 4, but they need to be taught to use it correctly; (Examples: SEREVENT, DISKUS, ADVAIR, FORADIL)

Dust Mites

Tiny, invisible bugs that live in carpets and fabrics. Dust mites eat human skin flakes; their droppings contain allergens that trigger allergic reactions in humans.


Eczema, or Atopic Dermatitis

An allergic condition of the skin; its symptoms include itching, dryness, redness or scaling. Eczema is often triggered by allergens in the air or by foods; 40 percent of children with eczema may have varying degrees of asthma.

Exercise-induced Asthma

Symptoms caused by increased demands on the respiratory system by physical exertion. With exercise, breathing is deeper and faster and air in the lungs is cooler and drier than usual. This is believed to stimulate inflammatory cells in the airways. The inflammatory cells, in turn, make the airways swell or produce mucus. The cells also irritate and tighten muscles that encircle the airways. Chest tightness and shortness of breath appear about five minutes after exercise begins, with wheezing and coughing following. Exercise-induced asthma can be improved by using short-acting bronchodilators 15 to 30 minutes before starting to exercise and by good everyday control of asthma.



An episode or "attack" when asthma symptoms become worse and cause increased breathing difficulties, coughing, wheezing, chest tightness or shortness of breath. Flares can be mild or severe; parents should know what to do when symptoms worsen into a flare.


Gastroesophageal Reflux Disease (also called acid reflux)

A condition in which stomach contents and acid travel back up the esophagus; reflux causes asthma worsening by irritating the esophagus and triggering a reflex action, directly increasing a bronchospasm in the airways. Reflux doesn't create an asthmatic condition per se, but when present in someone with asthma, it can make asthma control more difficult.



The reaction of tissues to irritants or injury, resulting in swelling, pain, redness or heat. Normally, inflammation can be helpful to the body by clearing harmful materials (such as infection, foreign matter like a splinter, or even tumor cells). In allergic inflammation, the body reacts to an allergen. In the case of asthma, the lining of airways becomes inflamed.


A small, hand-held device used to deliver medicine into the lungs. Inhalers come in various forms. Metered-dose inhalers (MDIs) deliver precise amounts of medicine with each inhaled puff; they should be used with spacers and require a slow deep breath. Dry-powder inhalers deliver medicine as a fine, dry powder and require a quick deep breath.



Natural substances produced by the body that cause muscles in the airways to contract and lung tissue to swell. The result — breathing difficulty — can be treated by anti-leukotrine medicine (non-steroid controller medicine) that reduces swelling.


Mast Cell

Cells found throughout the body that react quickly to allergens. When someone with allergies comes in contact with an allergen like pollen or dust, the body makes more naturally occurring antibodies called IgE, which then attach to mast cells and set off an allergic reaction; the mast cells burst open and release a number of substances, including histamine that causes redness, swelling and itching.

Mast Cell Stabilizers

A class of non-steroid controller medicine that reduces the release of inflammation-causing chemicals from mast cells; available in inhaled and/or nebulized form. Examples: CROMOLYN, NEDOCROMIL.

Metered-dose Inhaler (MDI)

A delivery device that releases an exact, measured amount of asthma medicine from an aerosol canister each time the child inhales a puff.



The cup part of a machine that delivers asthma medicine in a fine mist that is inhaled through either a facemask or mouthpiece; an attached air compressor provides a stream of air to create the mist. Liquid medicine is placed in the nebulizer cup and converted into small droplets that remain in the mist long enough to be inhaled into the lungs.


Peak Flow Meter

A small, inexpensive device that measures how fast air moves out of the child's lungs when a child exhales; it measures the peak expiratory flow (PEF) which is an indicator of airway size.

Pulmonary Function Test (PFT)

Assessment of the lungs' capacity and function; measures the amount of air and how fast it is exhaled.


A physician who specializes in respiratory (lung) conditions, including asthma.


Quick-relief Medicines

A group of medicines used to relieve asthma symptoms when they occur; sometimes also called "rescue" medicines. They are not used for prevention or control of asthma. Quick relief medicines work as short-acting bronchodilators that open the airways by relaxing the muscles that surround them.



A device attached to a metered dose inhaler (MDI) that helps deliver inhaled asthma medicine deep into the lungs. The spacer acts as "a holding chamber" because it holds, or suspends, the medicine spray so that a child can inhale a slow, deep breath. Spacers (such as AEROCHAMBER or OPTICHAMBER) are recommended because they help to reduce amount of medicine that can stick in the mouth or throat or be swallowed when using an MDI.


A special breathing test (also known as pulmonary function testing or PFT) that measures how blocked the airways are by the swelling and squeezing of asthma.



A bronchodilator used as both controller and quick-relief medicine; available in syrup, pill and injectable forms. Theophylline does not have significant anti-inflammatory effects, so it became less popular as a preventive treatment when the role of inflammation in asthma was recognized.


Any irritant or allergen that produces symptoms. Asthma triggers typically include viruses (colds and flu), environmental irritants (such as smoke, perfumes, and chemicals) and allergens (such as dust, pollen from grass and trees, pet dander, mold, dust mites and insects like cockroaches). When asthma is not well controlled, other triggers may also include physical exercise, laughing, crying or cold weather.



One of the common symptoms of asthma; sounds like a high-pitched whistling. Wheezing results from a narrowing of the airways that is caused by inflammation, tightening of muscles around airways, and excess mucus produced by the lungs. Not every patient with asthma will wheeze while having other symptoms. Wheezing can disappear when airways get very narrow — this is a sign of a serious flare.

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