Epinephrine vs Selective β2-Agonists in Adults or Children With Acute Asthma

Woman Injecting Epinephrine Using Auto-injector Syringe As An Emergency Treatment For Allergic Reaction
What is the efficacy of epinephrine vs selective β2-agonists in children and adults with acute asthma, and what is their combined efficacy?

Epinephrine and selective β2-agonists appear to have similar efficacy in acute asthma and limited available evidence does not support the use of epinephrine in addition to selective β2-agonists, according to a recent study published in Thorax.

International asthma guidelines recommend against the use of epinephrine in acute asthma except in the context of concomitant anaphylaxis or angioedema; however, many prehospital guidelines advocate administration of intramuscular epinephrine in addition to a nebulized selective β2-agonist for acute severe or life-threatening asthma.

Researchers conducted a systematic review and meta-analysis to determine the efficacy of epinephrine in comparison to selective β2-agonists in either children or adults with acute asthma. The researchers included peer-reviewed publications of randomized controlled trials (RCTs) in any health care setting and compared administration, by any route, of epinephrine vs selective β2-agonists for an acute asthma exacerbation. The primary outcome was treatment failure, including hospitalization, need for intubation, or death.

The analysis included 38 out of 1140 studies reviewed, with 17 studies involving 1299 participants contributing treatment-failure data for the meta-analysis. Researchers found significant statistical heterogeneity and that the overall quality of evidence was low. The pooled odds ratio for treatment failure with epinephrine vs selective β2-agonist was 0.99 (P=0.95). However, the patient’s age at recruitment was associated with different estimates of the odds of treatment failure, and studies recruiting adults only had lower odds of treatment failure with epinephrine. The researchers noted that it was not possible to determine whether epinephrine in addition to selective β2-agonist improved outcomes.

“The low-quality evidence available suggests that epinephrine and selective β2-agonists have similar efficacy in acute asthma,” concluded the researchers. They suggested that high-quality double-blind RCTs be conducted to determine whether the addition of intramuscular epinephrine to inhaled selective β2-agonists reduces the risk of treatment failure or death in adults or children with acute asthma.


Baggott C, Hardy JK, Sparks J, et al. Epinephrine (adrenaline) compared to selective beta-2-agonist in adults or children with acute asthma: a systematic review and meta-analysis. Thorax. Published online September 4, 2021. doi:10.1136/thoraxjnl-2021-217124