Sympathomimetics for acute severe asthma: should only beta 2-selective agonists be used? Sympathomimetics have become a mainstay of the treatment of acute asthma. Aerosolization of sympathomimetics provides as great or greater bronchodilation in acute severe asthma with fewer systemic effects than parenteral therapy. Despite the broncho-selectivity achieved with this route of administration, cardiostimulation remains the major, dose-limiting factor in the safe use of sustained, high-dose therapy with these agents. This article reviews the pharmacology, adverse effects, and toxicities of selected beta agonists, as well as clinical studies relevant to the question posed in the title. Although the ideal study to answer this question has not yet been performed, the authors feel that available evidence supports the preferential use of selective beta 2 agonists in patients with acute, severe asthma who will require high doses of beta agonists. 