How Do Asthma Inhalers Work?

Asthma Mechanism

Understanding how an asthma inhaler works requires an understanding of the physiology behind asthma. Asthma occurs when a hypersensitive immune system reacts to irritation of the airways. This irritation can be due to dust, smoke, stress, pollen or even just cold air. When these irritants enter the airway, they cause the immune system to be activated, which leads to inflammation. This inflammation causes the airway to swell and it also causes constriction of the muscles around the airway. The overall result is that the airway gets closed off, leading to wheezing and trouble breathing. The immune reaction also causes extra mucus to be produced by cells in the lungs, leading to coughing.

Inhaler Mechanism

The most common type of inhaler is called a "metered dose" inhaler. This type of inhaler contains a medication that is pressurized in a tube. When the trigger is pushed (often done by pushing down on the tube), the inhaler releases an amount of medication, which then can be sent to the lungs when the patient inhales. Some types of inhalers have a "spacer" that holds the medication when it's released, which makes it easier to inhale the full dose (this is useful for infants). A less common type of inhaler is called a "dry powder" inhaler, which doesn't use pressure to propel the medication. Instead, the medication is released when the patient inhales with a quick, deep breath.

Inhaler Medications

Most inhalers are used for symptomatic relief, which means that they contain drugs that work quickly to help stop asthma symptoms. The most common type is called beta-2 agonists. These medications work to help relax the muscles around the airway, which make it easier to breathe. Other inhalers provide medications to help prevent asthma attacks. These include inhaled corticosteroids, which help suppress the immune system in the lungs and prevent the inflammation that causes asthma symptoms.