Updated April 03, 2015.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Definition:

A metered dose inhaler (MDI) is one of the devices used to deliver inhaled asthma medication to your lungs. Your metered dose inhaler reliably releases a specific amount of asthma medication for inhalation with each use. It allows your asthma medication to get to your lungs more effectively than medications taken by mouth.

When you press the metered dose inhaler, a small mist of medicine is released that you can inhale directly or through a spacer (the mouthpiece on the inhalant's container).

MDIs can be used for both quick relief and controller medications.
Your MDI consists of three parts:

1. Metal canister- The canister contains the medication (under pressure) along with a propellant that will help get the medication to your lungs. A dosing chamber inside the MDI ensures that the same amount of medicine is released every time you press the actuator button.
2. Plastic sleeve & mouthpiece actuator- The metal canister fits inside the the plastic sleeve. When the actuator is pressed, medicine is aerosolized and forced through the mouthpiece
3. Mouthpiece cap- It is essential to replace the cap to keep your MDI clean and decrease your risk of getting an infection.

Some of the medications you can get as an MDI include:

Inhaled Steroids

• Aerobid
• Alvesco
• Azmacort
• Flovent
• Pulmicort
• Qvar

Short Acting Beta Agonists (SABA)

• Albuterol
• Proventil
• Ventolin
• Xopenex
• Maxair

Long Acting Beta Agonists (LABA)

• Brovana
• Perforomist
• Serevent

Cromolyn Sodium and Nedocromil

• Cromolyn Sodium (Intal)
• Nedocromil (Tilade)

Combination Drugs

• Symbicort

Learn More

• What You Need to Know About Your Metered Dose Inhaler
• Answers to Your Questions About Your Metered Dose Inhaler
• Step-by-step Guide to Using a Metered Dose Inhaler

Also Known As: puffer, asthma puffer, inhaler, asthma inhaler