The perceived need for intravenous antibiotics drives many hospital admissions. In a sense, the decision to administer IV antibiotics instead of oral formulations represents a line in the sand between infections we are worried might kill a patient and ones that won’t.

But for the vast majority of common infections we treat in the emergency department, oral antibiotics should actually be preferred over IV antibiotics when efficacy, safety, efficiency, and cost are taken into account together. My goal is to convince you to correctly choose oral antibiotics more often. I believe this will lead to fewer admissions, fewer hassles, and less suffering for our patients.

Of course, there are various physiological arguments that support oral antibiotics being theoretically as effective as IV antibiotics. But I know that, in order for us to change our behavior, the only thing that matters is whether data on outcomes support us. Here, I will concentrate on the clinically relevant outcome data for various indications and practical aspects comparing IV to oral antibiotics. Once armed with this knowledge, we should feel more comfortable prescribing pills and discharging rather than ordering IVs and admitting.

UTI and Pyelonephritis

Most urinary tract infections (UTIs) can be managed in the outpatient setting. In a Cochrane review of 15 randomized controlled trials (RCTs) comprising 1,743 children and adults with severe UTI, pooled outcomes showed no significant differences between oral and IV antibiotics.¹

But what about pyelonephritis? In adults with pyelonephritis and complicated UTI, oral fluoroquinolones have been shown to be noninferior to IV antibiotics.^2,3

And kids? Similarly, a Cochrane review of antibiotics for acute pyelonephritis in well-appearing children older than 1 month of age found no significant differences between oral antibiotics for 14 days and IV antibiotic therapy for three days followed by oral antibiotics, as well as no significant differences in persistent bacteriuria at the end of treatment or persistent kidney damage.⁴ A review in Annals of Emergency Medicine agreed with this assessment.⁵

Skin and Soft Tissue Infections

In multiple (albeit small) studies, no difference in clinical resolution of cellulitis has been demonstrated between IV and oral antibiotics for simple cellulitis.^6-8 One study, a RCT, found no difference in convenience, complications, effectiveness, overall satisfaction, and mean time to cessation of advancement of cellulitis between oral and IV antibiotics.⁸ A Cochrane review of 25 studies including 2,588 patients comparing oral and IV antibiotics for uncomplicated cellulitis looking at “symptoms rated by participant or medical practitioner or proportion symptom-free” found that IV antibiotics were no better than oral ones. In fact, two of the studies suggested that oral antibiotics were more effective!⁹

This comports with the Infectious Diseases Society of America recommendation that IV antibiotics for nonpurulent cellulitis be reserved for patients who are immunocompromised or have systemic signs of infection, hemodynamic instability, or altered mental status.¹⁰ In fact, adherence to this guideline has recently been shown to reduce treatment failure rates in ED patients.¹¹ In a recent retrospective chart review of 500 patients, independent predictors of oral antibiotic treatment failure (defined as hospitalization, change in class of oral antibiotic, or switch to IV therapy after 48 hours of oral therapy) for nonpurulent and soft tissue infections included tachypnea at triage, the presence of chronic ulcers, history of methicillin-resistant Staphylococcus aureus colonization or infection, previous recent cellulitis (in the past year), chronic kidney disease, and diabetes.¹²

One reason that IV antibiotics are overused is an incorrect diagnosis of “treatment failure.” All too often, patients with skin and soft tissue infections are deemed to have failed oral antibiotics after fewer than 48 hours of oral antibiotics. They then are needlessly switched to IV antibiotics. There is no evidence to support this practice. Treatment failure of simple cellulitis should only be entertained after a 48- to 72-hour trial of oral antibiotics. Even in many of these cases, switching classes of oral antibiotics is sufficient. IV antibiotics are not the automatic answer to “treatment failures.”