There are various types of inhalers containing different types of medication. The three main types are:

 Metered dose inhalers are somewhat like aerosol sprays. They consist of a pressurized canister connected to a mouthpiece. When the canister is pressed down, a measured dose of the medication is released into the mouthpiece. The mouthpiece is held at a distance from the mouth and the medication is inhaled through the mouth. The process may take about five minutes.

Metered dose inhalers with spacers are easier to use, as the spacer holds the medication and slowly releases it, making it easier to inhale. It decreases the amount of medication which sticks to the back of the throat and increases the amount that reaches the lungs.

Dry powder inhalers are devices that hold the medicine in powder form, in single doses. The devices can be found in disks or tubes (called turbohalers). The principle is to put the device in the mouth and inhale the powder in one breath. The advantage of dry powder inhalers is that they don’t need any propellant chemicals, unlike the two above.