A metered dose inhaler, usually called an inhaler, is a canister of medication that is under pressure. The canister is attached to a mouthpiece. The inhaler releases a mist of medication in a preset dose.

The medication reaches the small bronchioles more effectively if it is used correctly.

Inhalers contain:

• Short-acting bronchodilator:
• Quickly opens the narrowed air passages for a short time
• Long-acting bronchodilator:
• Opens the narrowed air passages for a long period
• Corticosteroid inhaler:
• Reduces swelling in the narrowed airways