The lungs have a huge surface area and a thin barrier between air and blood. That makes them an efficient route for drug delivery, especially for asthma and COPD. An inhaler is a device that turns a liquid or powder into an aerosol that patients breathe in. The drug acts directly on the airways, which means a smaller dose can work faster and with fewer systemic side effects than an oral pill.

There are three main types. Metered-dose inhalers use a pressurized canister to deliver a measured puff of drug. They require coordination: press the canister and breathe in at the same time. A spacer can make this easier by holding the aerosol cloud while the patient breathes. Dry powder inhalers are breath-actuated, meaning the patient's inhalation pulls the powder into the lungs. Nebulizers are machines that turn liquid medication into a mist, used for patients who cannot use the other devices or during severe attacks.

What patients should know:

• Technique matters. Poor technique is a common reason for treatment failure.
• Rinse after steroid inhalers. This prevents oral thrush.
• Spacers help. They improve delivery and reduce coordination problems.
• Rescue vs. controller. Know which inhaler is which and when to use it.

Pharmacists and respiratory therapists can check inhaler technique. A quick demonstration at the counter catches many errors.