dry-powder inhaler

A dry-powder inhaler, or DPI, delivers medicine as a tiny puff of fine powder rather than a wet spray. Instead of a propellant doing the work, your own inward breath pulls the powder out of the device and into your airways — so the inhaler is, in effect, breath-powered.

Each dose holds micronized drug particles, often blended with a coarser carrier powder such as lactose to help it flow. When you inhale sharply and deeply, the airflow shears the fine drug particles off the carrier and sweeps them into the lungs. Because there is no spray to chase, you do not have to coordinate a press with a breath, which many people find easier than a metered-dose inhaler.

The trade-off is that DPIs need a fast, forceful inhalation to break up the powder properly. People who are very breathless, very young, or very weak may not generate enough flow, so the dose underperforms. Humidity and breathing out into the device can also clump the powder, so DPIs should be kept dry and never exhaled into.