Which of the following medications is typically used as a rescue inhaler?

Albuterol is commonly used as a rescue inhaler because it is a short-acting beta-agonist (SABA) that works quickly to relieve asthma symptoms or acute bronchospasm. This medication relaxes the muscles of the airways, leading to bronchodilation and improving airflow, which is crucial during an asthma attack or when experiencing sudden breathing difficulties.

Other medications listed, such as fluticasone, are corticosteroids used for long-term management of asthma and chronic obstructive pulmonary disease (COPD) rather than immediate relief of acute symptoms. Dextromethorphan and codeine are cough suppressants, not respiratory medications, and do not address bronchospasm or airway constriction. Therefore, albuterol is the preferred choice for immediate use in emergency situations to effectively open the airways and alleviate symptoms quickly.