Continuous nebulization of beta 2 agonists is now recognized as a useful treatment for severe exacerbations of asthma. This mode of administration has been described both for adults and children in the emergency room and in the intensive care unit. It has been suggested that early use of continuous inhalation therapy may reduce or prevent the need for intensive care unit admissions and potentially toxic treatments such as intravenous beta agonists and mechanical ventilation. A number of methods have been proposed for continuous administration of beta agonists, however, there is no concensus as to the best one. The lack of controlled studies clearly demonstrating superior outcomes in patients who receive this treatment leaves many questions unanswered. In addition, differences in efficacy and safety between frequent and continuous nebulization, if any, are unclear. Adverse effects primarily consist of muscle cramps, hypokalemia, and hyperglycemia. It is suggested that use of this treatment should be considered for the asthmatic patient who demonstrates progression towards significant obstruction before institution of the more toxic treatments listed above. While continuous nebulization has not been proven to prevent the need for them, it is clearly safer. Should population studies eventually fail to demonstrate its superior efficacy, continuously nebulized beta 2 agonist therapy may still be beneficial for individual patients.