short-acting beta-agonist

A short-acting beta-agonist, or SABA, is the classic blue rescue inhaler — the one people reach for when their chest tightens and they need to breathe easier fast. Within minutes it relaxes the muscle wrapped around the airways, letting them widen so air can move more freely.

It works by stimulating beta-2 receptors on airway smooth muscle, which signals the muscle to relax. The relief comes on in a few minutes and lasts roughly four to six hours. Because it eases an existing spasm but does nothing for the underlying inflammation, it is a reliever rather than a controller — useful for sudden symptoms and before exercise, not for the day-to-day disease process.

Needing a SABA frequently is an important warning sign. Using more than about two canisters a year, or relying on it several times a week, suggests the underlying asthma is poorly controlled and that an anti-inflammatory inhaler is needed. Common, usually mild side effects include a fast heartbeat, tremor, and a jittery feeling.