Judicious antibiotic prescribing can help curb the development of antibiotic-resistant bacteria, but shorter courses are becoming more common for other reasons as well, including equal effectiveness and fewer side effects, according to clinicians and researchers.

Primary care clinicians account for approximately 80% of antibiotic prescribing, according to a recent review published in eClinicalMedicine, part of The Lancet Discovery Science. “Contrary to common belief, extending antibiotic treatment beyond the resolution of symptoms does not seem to prevent or reduce antimicrobial resistance,” the authors noted.

In 2021, the American College of Physicians issued updated clinical guidelines advocating the use of short-course antibiotics in four common infections: community-acquired pneumonia (CAP), acute bronchitis with chronic obstructive pulmonary disease (COPD), urinary tract infection (UTI), and cellulitis. For each of these, the recommendations advise a maximum of 5 days of antibiotics in most cases, with extension only if needed.

The recommendations are based on published clinical guidelines and peer-reviewed literature, including randomized clinical trials that have compared shorter antibiotic courses to longer ones.

Other medical organizations have endorsed and highlighted the evidence for shorter courses of antibiotics in recent years as well.

In 2024, the Journal of the Pediatric Infectious Diseases Society published a study making the case for 5 days as the default treatment duration for acute respiratory infections in children.

In 2025, the Infectious Diseases Society of America issued guidance for the treatment of complicated UTIs that included reducing the typical 14-day course to approximately 7 days.

Additionally, although not a formal recommendation, the Society for Healthcare Epidemiology of America highlighted a 2025 study in which shorter or no antibiotic treatment was as effective as the standard 10-day course for children with strep throat.

In general, physicians have prescribed longer antibiotic courses for CAP, acute bronchitis with COPD, UTI, and cellulitis, said William Callahan, DO, a family medicine physician at Jefferson Health in Abington, Pennsylvania. “But data show shorter courses are noninferior in efficacy and carry a lower risk of adverse effects,” he said.

However, newer guidelines stress that adopting shorter durations should be paired with evaluating clinical stability to ensure appropriate treatment. “This shift is about clinicians prescribing shorter durations of antibiotics, not patients arbitrarily discontinuing medication early,” Callahan said.

Guidelines recognize antibiotic resistance as a national threat, emphasizing that longer courses actually increase this risk through continued natural selection pressures in favor of resistant bacterial strains, he noted.

Newer guidelines speak to an overall trend in infectious diseases, said David J. Cennimo, MD, associate professor of medicine and pediatrics at Rutgers New Jersey Medical School, Newark, New Jersey.

Historically, clinicians prescribed long courses of 10-14 days, he said.

“These long periods are ‘overkill,’ and I use that word both figuratively and literally,” said Cennimo. “We have adequately treated the infection, but then overkilled the normal flora, especially the gut flora, and negatively impacted the gut microbiome,” he emphasized.

The potential impact of antibiotics on the gut microbiome is receiving more attention, although data on the association between course length of antibiotics and the long-term effects on gut microbiome are lacking, said Smit K. Shah, MD, education assistant professor of pediatrics at the University of Kansas School of Medicine, Kansas City, Kansas.

In the Clinic: Why Less May Be More

“I now routinely discuss the potential harms of antibiotics on the gut microbiome with patients,” Callahan said. He expands on these risks, including infection with pathogens such as Clostridoides difficile, and explains that more isn’t always better when it comes to antibiotics. In fact, in some cases, such as early sinusitis, antibiotics aren’t appropriate and carry much more risk than benefit, said Callahan.

This strategy is not about withholding necessary care as patients should receive antibiotic courses when appropriate, for recommended durations, he emphasized. Instead, “I stress the need to prevent harm, and I find that most patients appreciate this,” he said.

Research Gaps and Resources

Studies are needed to determine whether even shorter durations of antibiotics than those currently recommended would work in the general population, said Callahan. “When it comes to at-risk populations, such as those at higher risk for severe or recurrent infections, we need clarity on the appropriateness of shorter durations, and we should specifically define who is considered high-risk enough to warrant longer courses,” he said. “For acute infections, we continue to need easily attainable, point-of-care biomarkers to know when antibiotics are truly necessary.”

The growing body of data on the importance of the microbiome and the need to preserve it provides further impetus to determine how much clinicians can safely shorten needed antibiotics treatments, said Cennimo. “One of the most important factors is making sure the antibiotics are needed in the first place, for example, not treating viral upper respiratory infections with antibacterials,” he said.

“Another area of active research is the amount of intravenous antibiotics used vs switching to enteral antibiotics,” said Shah. Looking ahead, more noninferiority data are needed on the impact of shorter antibiotics courses for patients with conditions such as complicated pneumonia, septic joint infections, orbital cellulitis, osteomyelitis, and meningitis, he added.

For data on shorter courses of antibiotics for conditions beyond those identified in the ACP guideline, the Shorter is Better website curated by Brad Spellberg, MD, chief medical officer at the Los Angeles General Medical Center, lists clinical trials in support of reduced antibiotics for more than 20 conditions including bronchiectasis, osteomyelitis, and bacterial meningitis.

Callahan, Shah, Cennimo, and Spellberg had no financial conflicts to disclose.