10 Essential Asthma Terms You Should Know

by Kathi MacNaughton Health Professional


A chronic lung disease where the lining of the airways become inflamed, which means they narrow, tighten and fill with mucus. This makes breathing more difficult and causes symptoms such as wheezing, cough, shortness of breath and chest tightness. These symptoms can come and go in response to being exposed to certain environmental substances and conditions.


A common substance in the environment that does not bother most people, but that your body perceives as a threat to your health. As a result, your body mounts a defense called an allergic reaction, causing symptoms such as wheezing, chest tightness, shortness of breath and cough.


A substance, event or activity that brings on an inflammatory reaction in a sensitive person’s airways, resulting in asthma symptoms. Triggers can include allergens such as pollen or pet dander, activities like laughing or exercise, or things in the environment like strong odors, smoke and cold air. Each asthmatic’s triggers can be different and can also vary with the season or over time.

Asthma Action Plan

A personalized guideline for people with asthma to manage their disease and help keep it under control. The plan details symptoms and other measures that indicate when asthma control is slipping. It also lists your triggers and your medications. Finally, it provides instructions for what to do when control slips, including what medications to use and when to seek emergency help.


A protective response by your body in reaction to being exposed to an allergen or trigger. Inflammation is part of the allergic reaction in allergic asthma. It causes swelling and irritation in the lining of the airways, resulting in the hallmark symptoms of asthma-- wheezing, chest tightness, shortness of breath and cough.

Metered Dose Inhaler (MDI)

MDI is a small, handheld device that enables you to take certain types of asthma medication. When you place the mouthpiece of this plastic device into your mouth and press down on the medication canister, it converts liquid medicine into a fine mist and then, using an aerosol propellant, pushes the dose into your airways.

Dry Powder Inhaler (DPI)

DPI is a small, handheld device that enables you to inhale a powdered form of asthma medication. Unlike MDIs that use an aerosol propellant, DPIs use just the force of your lung inhalation to get the medicine into your airways. An example of this type of inhaler is Advair.

Rescue medication

A type of asthma medication, usually in inhaler form, that is fast-acting in relieving acute asthma symptoms as they arise. It works by relaxing and widening the muscles in your airways, making it easier for you to breathe. Rescue medications wear off fairly quickly and do not treat the underlying inflammation that causes asthma symptoms.

Controller medication

A type of asthma medication used to control and prevent the airway inflammation that triggers asthma symptoms. Some controller medicines widen and relax the airways, while others reduce the inflammation itself. They are slow-acting, taking days or weeks to reach full effectiveness, and should not be used to manage acute flare-ups.

Peak Flow Meter

A portable, handheld device you can use at home to measure how well your airways are working and how controlled your asthma is. You breathe into it and it gives you a reading on how forceful you are exhaling. Peak flow meters can detect problems with narrowing airways and asthma control even before you start having symptoms. They are an essential tool for managing asthma.

Kathi  MacNaughton
Meet Our Writer
Kathi MacNaughton

Kathi is an experienced consumer health education writer, with a prior career in nursing that spanned more than 30 years — much of it in the field of home health care. Over the past 15 years, she's been an avid contributor for a number of consumer health websites, specializing in asthma, allergy, and COPD. She writes not only as a healthcare professional, but also as a lifelong sufferer of severe allergies and mild asthma, and as a caregiver for her mother with COPD.