What are the dangers of using intravenous (IV) antibiotics when not needed?

Dangers of IV Antibiotics When Not Needed

Using intravenous antibiotics when not medically necessary exposes patients to serious risks including life-threatening Clostridioides difficile infection, antimicrobial resistance, direct drug toxicity, and infusion-related complications—all without providing any clinical benefit.

Antimicrobial Resistance and Superinfection

The most critical danger is driving antimicrobial resistance (AMR), which was responsible for 1.3 million deaths globally in 2019. 1

• Inappropriate antibiotic use—including using them when none are needed or using the wrong antibiotic at the wrong dose, duration, or route—affects 30-50% of all antibiotic prescriptions and is a well-established key driver of AMR 1
• Prolonged use of IV antibiotics results in overgrowth of nonsusceptible microorganisms, creating "superbugs" that colonize patients and spread to others 2
• The COVID-19 pandemic demonstrated this danger: most hospitalized patients received antibiotics despite SARS-CoV-2 being viral and rarely complicated by bacterial superinfections, further exacerbating selection of multidrug-resistant strains 1

Clostridioides difficile Infection (CDI)

IV antibiotics carry substantial risk for C. difficile infection, a potentially fatal complication that occurs even with short courses.

• One in five patients (20%) taking antibiotics will develop an adverse event requiring a doctor or emergency room visit, with C. difficile infection being among the most serious 1
• Hospital-onset CDI occurs at a rate of 7.3 per 10,000 patient-days, with every 50 days of therapy per 1,000 patient-days increasing CDI risk by 4.4% 3
• Specific IV antibiotics carry particularly high CDI risk: intravenous meropenem had the highest CDI rate at 3.56 per 1,000 days of therapy in recent surveillance 4
• Third- and fourth-generation cephalosporins increase CDI risk by 2.1% for every 10 days of therapy per 1,000 patient-days, while carbapenems increase risk by 2.9% 3
• Each additional unit increase in antibiotic spectrum intensity is associated with 1.09 times the risk of hospital-associated CDI 5
• CDI develops through microbiome disruption as antibiotics wipe out protective gut bacteria, allowing C. difficile to proliferate and produce toxins causing severe, sometimes fatal diarrhea 1, 6

Direct Drug Toxicity

IV antibiotics cause organ-specific toxicity that can result in permanent damage or death.

Nephrotoxicity

• IV aminoglycosides combined with other nephrotoxic agents (including NSAIDs) substantially increase risk of kidney injury 1
• Vancomycin requires monitoring of renal function when used with other potentially nephrotoxic drugs including amphotericin B, aminoglycosides, bacitracin, polymyxin B, colistin, viomycin, or cisplatin 2
• Meropenem dosing errors in patients with unrecognized renal impairment can lead to drug accumulation and toxicity 7

Ototoxicity

• Serial auditory function tests may be necessary to minimize risk of hearing loss with vancomycin 2

Hematologic Toxicity

• Reversible neutropenia occurs with vancomycin, requiring periodic leukocyte count monitoring during prolonged therapy 2
• Ceftriaxone can displace bilirubin from serum albumin and should not be given to hyperbilirubinemic neonates 8

Hepatobiliary Complications

• Ceftriaxone-calcium precipitates form in the gallbladder, appearing on ultrasound as sludge or gallstones, potentially causing symptomatic gallbladder disease requiring discontinuation 8
• Cases of pancreatitis, possibly secondary to biliary obstruction, have been reported with ceftriaxone 8

Urolithiasis and Renal Failure

• Ceftriaxone-calcium precipitates in the urinary tract can cause urolithiasis, ureteral obstruction, and post-renal acute renal failure, particularly in pediatric patients 8

Infusion-Related Complications

The IV route itself introduces mechanical and chemical risks absent with oral therapy.

• Thrombophlebitis occurs with IV antibiotics, requiring slow administration as dilute solutions and rotation of venous access sites 2
• Pain, tenderness, and tissue necrosis occur with inadvertent extravasation of IV antibiotics 2
• Infusion-related events including hypotension, flushing, erythema, urticaria, and pruritus increase with concomitant anesthetic agents 2
• Vancomycin must be given as a 60-minute infusion to minimize these reactions 2
• Chemical peritonitis has resulted from intraperitoneal vancomycin administration during continuous ambulatory peritoneal dialysis 2

Allergic and Anaphylactic Reactions

• Allergic reactions ranging from mild rash to life-threatening anaphylaxis occur with all IV antibiotics 1
• Concomitant administration of vancomycin and anesthetic agents has been associated with anaphylactoid reactions 2
• These reactions require immediate medical intervention and can be fatal 1

Drug Interactions and Monitoring Burden

• Ceftriaxone interacts with anticoagulants, requiring frequent monitoring of coagulation parameters during and after treatment 8
• Serum aminoglycoside levels become difficult to interpret when inhaled and IV aminoglycosides are used concomitantly, potentially leading to dosing errors 1
• The monitoring burden itself introduces risks of phlebotomy complications and healthcare costs without benefit when antibiotics are unnecessary 2

Loss of Future Treatment Options

Using IV antibiotics unnecessarily today eliminates treatment options for future infections.

• Skipping doses or unnecessary use increases the likelihood that bacteria will develop resistance and become untreatable by that antibiotic or other antibacterial drugs in the future 8, 7
• This creates a vicious cycle where increasingly broad-spectrum and toxic antibiotics become necessary for infections that were previously easily treatable 1

Common Clinical Pitfall

The most dangerous pitfall is prescribing IV antibiotics for viral respiratory tract infections, where large quantities are prescribed unnecessarily 1. The clinical benefit must always be weighed against these substantial risks, and when no bacterial infection is present, the risk-benefit ratio is entirely unfavorable 1.