Asthma narrows the airways. Muscles around the bronchi tighten, the lining swells, and mucus clogs the passage. Breathing out becomes hard work. Bronchodilators relax those muscles, opening the airway within minutes. They are rescue drugs, not controllers. They do not treat the underlying inflammation.

The main types are beta-2 agonists and anticholinergics. Short-acting beta-2 agonists like albuterol work in minutes and last four to six hours. They are the classic rescue inhaler. Long-acting beta-2 agonists like salmeterol last twelve hours or more and are used for maintenance, always in combination with an inhaled corticosteroid for asthma. Anticholinergics like ipratropium block a different pathway and are often used in COPD. Theophylline, an older oral bronchodilator, is rarely used now because of its narrow therapeutic window.

Practical points:

• Rescue vs. controller. Bronchodilators relieve symptoms; inhaled steroids reduce them over time.
• Technique. Inhaler technique matters as much as the drug. A spacer can help.
• Overuse. Needing a rescue inhaler more than twice a week suggests poor control.
• Side effects. Tremor, rapid heart rate, and headache are common with beta-2 agonists.

In an acute attack, bronchodilators are given by nebulizer for faster delivery.